Microbiology with Diseases by Taxonomy Chapter 23 Answers
Microbiology with Diseases by Taxonomy Chapter 23 Answers 1CM
The intestinal protozoan parasites are divided into four groups. They are ciliates, amoebae, the flagellates, and apicomplexans. The classification is clinically useful. It groups the parasites based primarily on the mode of locomotion.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 1CT
In the case of Entamoeba, 10% of the world’s population carries this parasite asymptomatically in the gastrointestinal tract. Once the disease develops, the annual mortality goes upto 100,000. In less developed countries, carriers are predominant. Infections with Acanthamoeba and Naegleria are rare compared to Entamoeba. So, Entamoeba infection is threat to more people in regard to incidence.
The clinical manifestation of Entamoeba is luminal amoebiasis, which is less severe invasive amebic dysentery. It is more serious and affects 500 million people worldwide and is the most serious invasive extra-intestinal amebiasis. Without adequate treatment the later two manifestations may be fatal.
In the case of Acanthamoeba, the amebic encephalitis caused is fatal. The manifestations are headache, altered mental state and neurological disorders. Symptoms worsen over a period of week till the patient dies. Physicians treat this disease with pentamidine. So, patient has few weeks to be diagnosed and treated.
In the case of Naegleria, the trophozoites enter the brain and cause amebic meningoencephalitis. The symptoms are severe headache, vomiting, fever, destruction of nervous tissue, brain hemorrhage leading to coma. Physicians treat the disease with amphotericin. After the onset of symptoms, the patient dies within three to seven days. By the time the disease is diagnosed, patient dies. So, Naegleria infection is the most serious one.
The answer is not same for both questions, because even if the incidence is high in the case of Entamoeba, it can be diagnosed and treated, so that the life is saved. In the case of Acanthamoeba, after the onset of symptoms, the patient has few weeks to be diagnosed and treated.
But, in the case of Naegleria the patient dies within three days to seven days after the onset of symptoms. So, there is very little chance or no chance of saving the life of the person infected with Naegleria. Hence, the mortality rate is almost 100% in this case.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 1FB
Balantidium coli can be distinguished from Entamoeba histolytica microscopically because B. coli have cilia.
Balantidium coli belong to ciliate protozoan species, whereas Entamoeba histolytica, also a parasitic protozoan, belongs to Amoebae.
Ciliates are protozoan parasites with cilia. The trophozoites use cilia for locomotion and for acquiring food. Balantidium is a large ciliate and is the only ciliate pathogenic to humans. Humans are infected by ingestion of cysts with contaminated food and water. In the small intestine, encystment occurs and the trophozoites are released. They have cilia with which it attaches itself to the intestine and also burrow through the intestinal mucosa.
Entamoeba move and acquire food with pseudopodia and is the most important pathogenic amoeba.
Hence, the correct answer is cilia.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 1L
The plasmodium life cycle has three stages. They are exo-erythrocytic phase, erythrocytic cycle, and sporogonic phase. The given diagram is labeled as follows:
The life cycle of Plasmodium has three stages. They are as follows:
1. Exo-erythrocytic phase –
The forms of the parasite involved are sporozoites and merozoites. Sporozoites are injected into the human by Anopheles mosquito. They enter the liver cells through the blood circulation. Schizogony occurs in liver cells and merozoites are formed.
2. Erythrocytic cycle –
The forms of the parasite involved in this cycle are merozoites, trophozoites and male and female gametocytes. Merozoites in the blood circulation enter the erythrocytes and change into trophozoites. Trophozoites undergo schizogony and produce more merozoites. These merozoites lyse the erythrocytes and enter the blood circulation. Some of the merozoites stay in the erythrocytes and form male and female gametocytes.
3. Sporogonic phase –
The forms of the parasite in this cycle are gametocytes, oocyst, and sporozoites. The gametocytes in the erythrocytes are ingested by mosquitoes. In the digestive tract of mosquitoes the gametocytes are freed. The fertilization takes place and zygotes are formed. The zygote becomes an ookinete, which becomes an oocyst. After meiosis, oocyst ruptures and sporozoites are formed. Thousands of sporozoites migrate into the salivary glands of the mosquito, which in turn is injected into a new host.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 1M
The term “Balantidium coli” matches with option (G) trophozoites.
This ciliate protozoan infects the humans. It causes balantidiasis. It is transmitted through feco-oral route. This parasite has two developmental stages. One is trophozoite stage and the other is cyst stage.
The trophozoite has two nuclei. This macronucleoi is sausage shaped and long and the micronucleus is situated next to it and is hidden by it. It has a pointed end anteriorly and an opening called peristome is situated at this end. This leads to the mouth called cytosome.
The infection is caused by the ingestion of cyst. As soon as it reaches the small intestine, trophozoites are produced. In the large intestine, the trophozoites colonize and feed on intestinal flora.
Some of the trophozoites live in lumen of the intestine and get disintegrated and encysted. Some of them penetrate the wall of the large intestine by proteolytic enzymes and are multiplied.
Hence, the term “Balantidium coli” matches with (G) trophozoites.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 1MC
Parasitology is the study of parasitic eukaryotes. It has two categories. One is protozoan parasites and the other is helminthic parasites. This is in the case of both humans and animals.
Parasites are organisms that live, grow, and feed on other host organisms. All the parasites have a definite host where as some have one or even more intermediate hosts.
Protozoan parasites are one-celled eukaryotic organisms. It includes amoebae and flagellates like Giradia. They could enter into an organism’s body intracellularly and extracellularly.
Helminthic parasites are multicellular worms. They enter the body extracellularly. Roundworms and flatworms are examples. Hence, the correct option is (d) Parasitic eukaryotes.
Parasitology is not the study of viruses. The study of viruses is called Virology and it is focused only on viruses. The viruses are parasitic particles, which infect the host cells and reproduce only inside the living cell. Hence, option (a) is not correct.
Parasitology is not the study of parasitic prokaryotes. Prokaryotes do not have a nucleus. Bacteria and archaea are prokaryotes. They can live in any environment. Some prokaryotes live as symbionts in the bodies or on the bodies of humans and other organisms. Hence, the option (b) is not correct.
Parasitology is not the study of parasitic fungi. The study of fungi is called mycology. Many fungi live as parasites on plants, animals and humans. Most of them are small in size. Some fungi live in soil, dead matter and on plants as symbionts. Hence, the option (c) is not correct.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 1MTF
The statement “Sexual contact is the most common method of transmitting parasites” is false.
Ingestion is the most common method of transmitting parasites.
For example, the cysts of the protozoan parasites are voided along with the feces. These cysts are ingested by contamination of water or food.
In the case of Entamoeba histolytica, Balantidium and Giaridia duodenalis the cysts voided along with feces is ingested.
Hence, the correct statement is “Ingestion is the most common method of transmitting parasites.”
Microbiology with Diseases by Taxonomy Chapter 23 Answers 1SA
Animal reservoir is the animal, which hosts the parasite and transmits by itself being immune to its effects. There are many animal reservoirs for many parasites, which affect humans. The zoonotic diseases are difficult to eradicate, as they are transmitted from animals.
Pigs are common animal reservoirs. They are asymptomatic. For example, the ciliate Balantidium coli occur when humans have close contact with pigs. The cysts of this parasite contaminate water sources.
As the animal reservoirs are asymptomatic, we cannot treat the animals nor can altogether eradicate the animals. For effective control of vector, precise sampling, showing the prevalence of the disease is needed.
The zoonotic diseases, which are vector borne act as bridge vectors transmitting the parasites to humans, to animals, and animals to humans. For example, leishmaniasis, babesiosis, and filariasis transmitted by vectors from animals are increasing. These infections affect domestic animals making them animal reservoirs. As the eradication of animals is rejected ethically, only the vectors should be controlled to eliminate such diseases.
The climatic change in the world causes alterations in the parasites’ transmission, which are transmitted by vectors. Hence, the animal reservoirs and insect vectors make it difficult to prevent or control the parasitic infections in humans.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 2CT
(a) Global warming can lead to the reemergence of malaria in the U.S. Malaria is endemic in tropic and sub tropic regions. This is the ideal climate for the mosquitoes to bread. Because of the global warming, the U.S also gets a climate like the tropics enhancing the breeding of mosquito vectors.
(b) Increased travel of individuals from endemic regions to U.S is a great risk for the reemergence of malaria, as they may be carriers of the disease. The movement of infected persons and mosquitoes from the endemic areas to U.S is a threat to reintroduce this disease in U.S.
(c) Increased immigration of individuals from endemic regions to U.S also lead to reappearance of malaria in U.S. Individuals form endemic areas may be carriers of this parasite. So, they will be spreading this parasite to the new host through the mosquito vectors.
(d) Regulations against the use of insecticides:
The insecticide DDT (Dichloro-diphenyl-trichloro-ethane) was used in the eradication of malaria. The mosquitoes developed resistance to DDT and it is an important factor in the reemergence of malaria. The effects of DDT on the environment and ecology, made us to abandon their use. Widespread use of insecticides can reduce mosquito breeding rates. As it is restricted there is reemergence of malaria.
(e) Laws protecting the wet lands:
The mosquitoes breed in wet lands. If there is drainage of wet lands and removal of standing water, there will be very much reduced production of mosquito vectors. As there are laws to protect the wet lands to maintain the ecology, the mosquitoes also breed and multiply.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 2FB
Toxoplasma gondii can be transmitted to humans from cat litter box.
This parasite is a protozoan and it causes toxoplasmosis. It infects the warm blooded animals. It is common in humans and asymptomatic in healthy individuals. In people with HIV (human immunodeficiency virus) and low immunity, this infection can be fatal. The ingestion of cysts by eating raw and uncooked meat, contamination of water and food with feces, is the root of infection.
Cats are the only hosts in which the parasite reproduces sexually. Cats get infected by eating a mouse infected with cysts. These cysts enter the gastro intestinal tract of the cat and infect the small intestine. Here the sexual reproduction takes place and oocysts are formed. Immature oocysts are shed along with cat feces.
Contact with infected cats and their feces is a great risk of infection. Cat can excrete ten million oocysts per day. These oocysts can live in moist soil for many months.
The oocysts are ingested by humans by contact with cat’s feces. Transplacental transfer of Toxoplama from the mother to the fetus in the first three months of pregnancy is very dangerous, as it causes congenital anomalies, or abortion, or still birth.
Hence, the correct answer is Toxoplasma gondii.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 2M
The term Echinococcus granulosus matches with (E) hydatid cyst.
This parasite is also called Hydatid worm or dog tape worm. This parasite lives in the small intestine of canids. Canids get this infection by the ingestion of cysticerci in herbivorus animals like cattle, sheep, and so on.
The intermediate hosts are sheep, cattle, and humans also. Humans get infected by ingestion of the eggs shed with dog’s feces. Inside the intestine, the larvae are released and these larvae enter the blood circulation and travel all over the body and form hydatid cysts in the body of the host. This is called hydatid disease.
These hydatid cysts get calcified over the years and get enlarged. They are filled with fluid and millions of protoscoleces. Every protoscolex can grow into a new worm. These hydatid cysts, if enlarged can cause tissue dysfunction. In the liver, it causes obstruction of bile ducts. If they are seen in heart, lungs, kidneys, and brain, that can be fatal.
When the cyst ruptures, millions of the protoscoleces spread throughout the body.
Diagnosis of this disease can be done by the visualization of the hydatid cyst in radiography, CT scan, and ultrasonography. Serological confirmation through immunoassay can also be done.
Treatment is by the surgical removal of the cysts followed by a course of albendazole. Infection can be prevented by good hygiene and by drinking treated water.
Hence, the term Echinococcus granulosus matches with (E) hydatid cyst.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 2MC
The only ciliate to cause disease in humans is Balantidium. This is a parasite of ciliate protozoa. This parasite is surrounded by cilia. The trophozoites use cilia for locomotion. It causes Balantidiasis in humans. Its normal host is pig.
The parasite is asymptomatic in pig. It infects the humans through feco-oral route. The cysts are ingested through water and food contamination. In healthy individuals it does not cause serious problems of gastrointestinal tract. In people with malnutrition infection occurs due to low acidity in the stomach. In acute cases, diarrhea may be very severe. Perforation of colon also occurs in acute infections. Hence, the correct option is (b) Balantidium.
Naegleria is not a ciliate. It is classified as amoeba. They are protozoa that have no defined shape and move with the help of pseudopodia. Naegleria may assume flagellated form also. Naegleria infection causes amebic meningoencephalitis. Hence, the option (a) is not correct.
Fasciola comes under genus trematodes. It is a helminthic parasite of humans. They belong to liver flukes. It is not a protozoan ciliate. Fasciola hepatica and Fasciola gigantica are two species of Fasciola. Acute infection occurs when the parasite moves from the intestine to the liver. Chronic infection starts when fluke migrates into bile ducts. Hence, the option (c) is not correct.
Trypanosomes are flagellate protozoa. It is not a ciliate. They cause various diseases including sleeping sickness by Trypanosoma brucei and Chagas disease by Trypanosoma cruci. Hence the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 2MTF
The statement “examination of stools samples can reveal the presence of Naegleria parasites” is false.
Naegleria is a protozoan parasite. It affects the brain and causes severe damage. Naegleria fowleri affects humans. These amoebae are seen in ponds, lakes, swimming pools and dialysis units. So, people who swim in the pools, lakes, rivers and in swimming pools with inadequate chlorination can inhale this parasite through their nose.
People who use contact lens get this infection by washing and storing their lens in unsterile tap water. This becomes a focal point for this infection.
When this amoeba enters the brain, it causes amoebic meningoencephalitis. This causes severe headache, fever, destruction of neurological tissues that leads to hemorrhage and coma. This results in death within a week. This parasite assumes flagellated form along with its amoeboid and cyst stages.
Hence, the correct statement is “examination of corneal scrapings, cerebrospinal fluid and also by taking material for biopsy can reveal the presence of Naegleria parasites.”
Microbiology with Diseases by Taxonomy Chapter 23 Answers 2SA
The transmission of amoeba Entamoeba is by ingestion of cysts. These cysts are ingested through contaminated water and food. When the human excreta are used to manure the crops and where the sanitation is not proper, the carriers of the parasite increase. There are no animal reservoirs for this parasite. But, human carriers continuously transmit this parasite. Fecal contamination of hands and oral-anal intercourse are also causes of the transmission. As the cysts are hard, normal water treatment will not eliminate the cysts.
The transmission of Acanthamoeba is through direct contact. Through the cuts or scratches on the skin, through the abrasions caused by the contact lens in the conjunctiva or any injury, the trophozoites can enter the humans. The parasite may enter the host while swimming, if the water is contaminated with the parasite.
In the case Naegleria, the mode of transmission is through inhalation. When the swimmers swim in the water contaminated with trophozoites of this parasite, the trophozoites enter the nasal mucosa and multiply. The trophozoites enter the brain and cause amebic meningoencephalitis.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 3CT
The intestinal microbes affecting the patients with HIV (Human Immune Virus) increase the disease progression. In these patients, the gut immunity fails and the pathogens cross the intestinal mucosal barrier and enter the circulation, causing great loss of gut residing CD4+ T-cells.
Cryptosporidium causes diarrhea, which is self-limiting in people with normal immune system. In AIDS (acquired immunodeficiency syndrome) patients, the symptoms are severe and fatal often. In AIDS patients, this parasite resolves very slowly or does not resolve. It causes watery diarrhea with greatly reduced ability to absorb important nutrients through the intestine.
Visceral leishmaniasis in AIDS patients is a problematic condition. Toxoplasmosis is severe in AIDS patients. The immune system fails, as the pseudocysts reactivate. Patients with AIDS will have severe episodes of malaria, as they have poor immune system.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 3FB
African sleeping sickness is caused by Trypanosoma brucei, but not by Trypanosoma cruzi.
African sleeping sickness is a caused by parasite protozoan Trypanosoma brucei by the insect vector tsetse fly. This parasite has two variants namely Trypanosoma brucei gambeinse, which occurs in western Africa and Trypanosoma brucei rhodesiense, which occurs in eastern and southern Africa.
This sickness is also called African lethargy. This disease is seen mostly in equatorial and subequatorial savanna and is endemic in sub-Saharan Africa. One third of the populations of Africa are at risk of getting this disease.
The epimastigote stage of this parasite changes into infective trypomastigote in the salivary gland of male or female tsetse fly. These infective forms are injected into the humans or animals during blood meal. These parasites move throughout circulatory and lymphatic system and reproduce by binary fission. In this stage, the patient experience lymph node swellings. This may lead to anemia, cardiac problems, and kidney problems.
Some of the trypomastigotes enter the central nervous system. At this stage, there will be disruption in the sleep cycle. Hence, this disease got this name. Along with this, there will be muscle weakness, tremor, confusion, and hemiparesis.
In the absence of treatment, there will be mental deterioration, and organ failure, which will lead to death. Therefore, the correct answers are brucei and cruzi.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 3M
The term Fasciola spp matches with (A) Miracidia.
Fasciola is a trematode. The eggs of this trematode hatches in the fresh water and miracidia forms. It seeks the intermediate host that is snails. The miracidia then undergoes two or three cycles of asexual reproduction inside the snail. Then cercariae larvae are produced.
Miracidia is a free moving form and is covered with cilia. It develops into sporocyst inside the snail.
There are two species of Fasciola. One is Fasciola hepatica and the other is Fasciola gigantica. They cause infection in cattle and sheep. When the humans ingest the metacercariae from aquatic plants like water cress, they get infected. The encysted larvae migrate from the large intestine to the liver and then to the bile duct to reside and mature there.
Heavy infections with this parasite can cause liver failure. Hence, the term Fasciola matches with (A) Miracidia.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 3MC
- The regular sexually transmitted diseases are caused by an organism, known as trichomonas. It causes trichomoniasis. This infection is caused in urogenital tract. The common site of this trichomoniasis is urethra and vagina in women. In men, this protozoan parasite lives in urethra and prostrate. The only reservoir of Trichomonas vaginalis is the genital tract of humans. Hence, the correct option is (a) Trichomonas.
- Entamoeba is a protozoan parasite under the classification Ameoeba. It causes amoebiasis. The active stage of this parasite is trophozoite stage. This stage exists only in the host organism and in loose feces freshly passed. Infection occurs by drinking contaminated water with cysts. These cysts can be ingested due to fecal contamination in food and also due to oral-anal intercourse. Entamoeba is not an organism that causes regularly sexually transmitted organism. So, the option (b) is incorrect.
- Trypanosoma is not a regularly sexually transmitted organism. It is a protozoan flagellate parasite. They are mainly transmitted by a vector. Trypanosoma cruzi is transmitted by kissing bug and Trypanosoma brucei is transmitted by tsetse fly and causes Chagas disease and sleeping sickness respectively. Hence the option (c) is incorrect.
- Enterobius is not a regularly sexually transmitted organism. This is commonly called pinworm. It is a nematode. It is a parasite which lives in the human intestine. It causes enterobiasis. This parasite is transmitted by ingestion through human to human. The eggs of the worms are deposited around the anus and are transmitted by contamination of food, water, bathroom taps, bed linen, clothes and so on. The eggs can be airborne and can be dispersed and can enter mouth or nose through inhalation. Hence, the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 3MTF
The given statement is true.
Trypanosoma brucei is a flagellated protozoan parasite. It causes trichomoniasis. This parasite is transmitted by sexual contact only. It lives in the vulva and vaginas of women and in men, in urethra and prostate gland. They cannot live outside the host for a long time.
In the life cycle of trichomonas there is no cystic stage. So, trophozoites are transmitted directly. Trichomoniasis mostly occurs in patients who are already having sexually transmitted diseases.
Women with vaginosis due to this infection will have foul smelling purulent vaginal discharge, abdominal pain, dysuria, and painful coitus. Because of this infection, the vaginal endometrium is damaged. This increases the susceptibility of women to HIV (Human immuno deficiency virus) infection. Men having this trichomanal infection are usually asymptomatic.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 4CT
Sickle cell trait is advantageous to people living in malaria endemic areas. The people having this trait have hemoglobin S. It is an abnormal type of hemoglobin. The normal hemoglobin is A.
This hemoglobin S makes the erythrocytes to become sickle shaped and resist the penetration of the malarial parasite into the erythrocytes. Hence, people with this trait will have survival advantage and there will be less mortality due to malaria when Plamodium falciparum is the causative parasite.
The sickle cell trait may cause renal medullary carcinoma, hematuria, urinary infection, and sudden death during exertion. Hence, this trait is not advantageous in malaria free areas.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 4FB
The parasitic amoeba Entamoeba can be acquired by ingestion.
Entamoeba causes amoebic dysentery. Entamoeba histolytica lives in the digestive tracts of human. In less developed countries, due to the usage of human excreta as a fertilizer for crops, this parasite is predominant. There are numerous human carriers of this disease in industrialized populations also. So, there is continuous transmission of this parasite.
Infection occurs through ingestion of cysts. Food and drinking water gets contaminated with feces containing the cysts of this parasite. Also during oral-anal intercourse the cysts are ingested. The parasite can be ingested due to the contamination of hands with fecal matter.
There are three types of amebiasis. One is luminal amebiasis, in which the trophozoites remain asymptomatic and it happens with rather healthy individuals. The second one is invasive amebic dysentery, in which diarrhea, colitis, with amebic dysentery. The third one is invasive extraintestinal amebiasis. This can be fatal if not treated. Therefore, the correct answer is Entamoeba.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 4M
The term Leishmania spp matches with (H) Amastigotes.
In Leishmaniasis amastigote stage occurs in vertebrate host.
Leishamania is a protozoan parasite and causes Leishmaniasis. It is transmitted by the sand fly. The promastigotes are infective stage of this parasite. This stage of the parasite is injected into the humans by the sand flies during the blood meal.
These promastigotes are phagocytized by macrophages and are changed into amastigotes. They increase and multiply inside the macrophages by binary fission. Then the macrophages rupture releasing the amastigotes, which in turn affect the other macrophages.
During the initial stages of infection, the macrophages responds, but it is not sufficient to destroy the intercellular amastigotes. Inflammatory responses are continuous due to infection of new macrophages. As the number of macrophages decreases, the immune response also declines.
In visceral leishmaniasis, the macrophages spread the amastigotes to liver, spleen, lymph nodes, and so on. If untreated, this disease can be fatal.
The amastigotes are identified microscopically in skin lesions, spleen, and bone marrow samples. This is a diagnostic feature of leishmaniasis. Hence, the term Leishmania matches with (H) Amastigotes.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 4MC
Leishmania species are transmitted by sand flies. Leishmaniasis is caused by this protozoan parasite. It is zoonosis, that is, it is a animal disease transmitted to humans. Female sandflies inject the promastigotes, the infective stage of this parasite into humans. These promastigotes are phagocytized by macrophages and are changed into amastigotes. They affect the cells and tissues depending on the species of Leishmania and the clinical manifestations also differ according to that. Sand flies ingest the macrophages when they bite an infected person. In the sand fly’s midgut the parasite undergo changes and become promastigotes and then into metacyclic promastigotes. In this stage, the parasite migrates to the proboscis of the sandfly.
Hence, the correct option is (a) sand flies.
Leishmania species are not transmitted by tsetse flies. These flies are vectors of trypanosome brucei which cause human sleeping sickness. They suck the infected blood from the vertebrate host and inject the parasite into uninfected animals. Hence, the option (b) is not correct.
Kissing bugs do not transmit Leishmania species. These bugs feed the blood of vertebrates and are vectors of Trypanosoma cruzi, which cause Chagas disease. These bugs feed from the blood vessels of lips, hence got this name. Inside the hindgut of the bug, epimastigotes develop into trypomastigotes which are infective stage of the parasite. Hence, the option (c) is incorrect.
Mosquitoes do not transmit Leishmania species. Mosquitoes are vectors for the transmission of many parasitic and viral infections. Anopheles mosquito is the vector for plasmodium which causes malaria. Female mosquitoes of Culex, Aedes and Anopheles are vectors of microfilaria larvae. Hence, mosquitoes do not transmit Leishmania species.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 4MTF
The given statement is true.
Trypanosoma brucei is transmitted by an insect vector called tsetse fly. They cause the disease African sleeping sickness. This is seen commonly in equatorial and sub equatorial areas of Africa. If not treated early, this is 100% fatal.
In the male and female tsetse flies, the epimastigote stage of this parasite changes into trypomastigotes. When the mosquito bites the human, the trypomastigotes enter the blood circulation. Some of them enter the central nervous system and cause meningoencephalitis. This cause abnormal neurological functions, and coma and leads to death in six months time of onset of symptoms.
The parasites in the blood circulation causes a condition by changing its surface glycoproteins so that the patient is incapable of being freed from the infection and never can become immune to that infection.
Trypanosoma cruzi is transmitted by kissing bugs scientifically named triatomine bug. This bug deposits its feces with the trypomastigotes in the skin. Scratching this area by the host helps the trypomastigotes to penetrate the skin.
This parasite causes Chagas disease. In its acute stage, amastgotes are seen in the swelling at the site of bite. The other stage is that this parasite affects the internal organs such as heart, colon, and esophagus and so on. This parasite induces heart disease and can cause death.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 5CT
Trypanosoma cruzi causes Chagas’ disease. The clinical manifestations of this disease are chagomas, which are swellings at the sites of bite by the kissing bug. It is an acute stage.
The trypomastigotes enter the blood stream and penetrate heart muscles, macrophages, and get changed into amastigotes. This is a generalized stage. Fever, lymph nodes enlargement, inflammation of heart muscles (myocarditis), spleenomegaly, inflammation of esophagus and colon are notable symptoms of this stage.
The amastigotes undergo binary fission and multiply. Some of them infect other cells and some of the amastigotes change into trypomastigotes and circulate in the blood. They are ingested by the kissing bug during the blood meal. A chronic stage comes after this and it is for years.
Amastigotes form pseudocysts in the heart muscles causing congestive cardiac failure. This is called asymptomatic stage. The leading cause of death due to this parasite in Latin America is parasite induced heart disease.
Trypanosoma brucei causes African sleeping sickness. This disease if untreated can go through three stages of clinical manifestations.
Number one is wound formed at the site of the bite by tsetse fly. The fly injects trypomastigotes into the wounds. This lesion has rapidly dividing parasites and dead tissue.
Second stage is trypomastigotes, they enter the lymphatic and blood circulation and undergo binary fission and multiply. The parasite in the blood circulation cause fever, head ache, and swelling of lymph nodes.
The third stage is some trypomastigotes. They enter central nervous system (CNS). The manifestations of this stage are meningoencephalitis. The patient experiences headache, abnormal neurological functions, and coma. The patient may die within three to six months from the time of onset of symptoms.
The differences in the clinical manifestations are as follows:
- In Trypanosoma cruzi, the trypomastigotes enter heart muscles, spleen from the blood circulation, but in Trypanosoma brucei, the trypomastigotes enter the central nervous system.
- The cause of death is due to parasite induced heart disease in the case of Trypanosoma cruzi, while the cause of death is due to meningoencephlitis in the case of Trypanosoma brucei.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 5FB
Plasmodium vivax and Plasmodium ovale both can form dormant hypnozoites.
Other plasmodium species do not have hypnozoites.
Latent hepatic stage of these parasites is called hypnozoites. These hypnozoites cause malaria even long time after the mosquito bite.
The sporozoites are injected into the human by the bite of female anopheles mosquito. They enter the blood stream and enter the liver and undergo schizogony. Merozoites are produced, which rupture the liver cells and enter into blood circulation.
In the case of Plasmodium vivax and Plasmodium ovale, a resting stage of the parasite is formed. This is called hypnozoites. Hypnozoites remains dormant in the liver cells for years. It is reactivated at any time causing relapses of malaria. Therefore, the correct answer is hypnozoites.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 5M
Plasmodium falciparum matches with (C) Schizogony and (G) trophozoites.
This parasite has three stages. In the first stage, the erythrocytic phase, the sporozoites of this parasite are injected into humans by female anopheles mosquito. These sporozoites enter the liver tissue and undergo schizogony in the liver cells. As a result of schizogony, merozoites are produced. They rupture the liver cells and enter the blood circulation.
These circulating merozoites enter the erythrocytes. This is erythrocytic cycle. The merozoites change into trophozoites. They can endocytize the hemoglobin of erythrocytes. Trophozoites undergo schizogony and more merozoites are produced. These cause the lysis of erythrocytes. Erythrocytes are destroyed continuously and cyclically.
Plasmodium falciparum causes blackwater fever. In this disease, large amount of erythrocytes are destroyed and results in renal failure. Dark colored urine is produced due to excretion of hemoglobin.
Erythrocytes become rigid and lose its elasticity due to the parasite protein being inserted on the surfaces of infected erythrocytes. This causes blockage in the flow of blood and tissue hemorrhages. This leads to tissue death. Cerebral malaria results if the tissue death happens in the brain. Within 24 hours of the onset of symptoms, Plasmodium falciparum can be fatal.
Hence, the term Plasmodium falciparum matches with the options (C) schizogony and (G) trophozoites.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 5MC
The intracellular infection stage of leishmaniasis is amastigote. Leishmaniasis is transmitted by female sandflies. These sandflies inject metacyclic promastigotes as it bites the host. The macrophages phagocytize the promastigotes and amastogotes are formed. These amastigotes multiply in number in the infected cells. As the macrophages rupture, the amastigotes are released. They infect other macrophages and also circulate in the blood stream. At this stage it is ingested by other sand fly.
Hence, the correct option is (d) amastigote.
Miracidia are free swimming larvae of trematodes called flukes. These miracidia are within 24 hours of hatching, enter into a mollusc host. After two or three cycles of asexual reproduction, they become cercaria larva. The cercariae leave the snail host and enter the next host depending on the type of parasite whether it is blood fluke, liver fluke and so on. Hence, the option (a) is incorrect.
Metacercaria is cercariae, the larvae of fluke, encysted and in resting stage. The cercariae, larval stage of intestinal and liver fluke, encyst on vegetation. In lung flukes and some of the liver and intestinal flukes, the cercariae encyst and metacercariae is formed inside a second intermediate host. Hence, the option (b) is incorrect.
Bradyzoite is one of the stages of zoonotic organisms like Toxoplasma gonadi. It is slow growing form and hence got this name bradyzoite. The sporozoites reproduce asexually and produce bradyzoites. Around the masses of cells with bradyzoites thick walls are formed. These form pseudocysts. These pseudocysts enter the cat’s intestine and these parasites become gametes. Hence the option (c) is not correct.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 5MTF
The given statement is true.
This parasite is a protozoan parasite and belongs to the genus Plasmodium. It is a more virulent species. Its insect vector is female anopheles mosquito. Malaria caused by this parasite is the most serious form of malaria and it is also called malignant malaria. This falciparum malaria has many complications and its mortality rate is high. In Africa most of the cases of malaria is falciparum malaria.
As soon as humans are bitten by the infected mosquito, sporozoites are injected and enter the blood stream. Within 30 minutes sporozoites all invade the liver cells. In the liver merozoites are produced. They are released from the liver cells by bursting them and enter the red blood cells. Schizonts are produced. Each schizont has 12-16 merozoites. When the red blood cells get ruptured and the merozoites are released, the patient experiences fever with rigor.
The sequestration is the distinctive property of Plasmodium falciparum. They change the surface properties of infected erythrocytes and make them to adhere to the blood vessels. So, there is obstruction of blood circulation in the capillaries, which leads to multi organ failure. Mainly it is brain and it is called cerebral malaria.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 6CT
In the case of Trypanosoma brucei, the infections are characterized by cyclical waves of parasitemia. That is, presence of the parasite in the blood circulation. It occurs every 7-10 days.
For every cycle, the parasite changes its surface glycoproteins and thereby surface antigen. By the time the host produces the antibodies for the glycoprotein, the parasite already produces new set of glycoproteins.
This makes the host always one step behind the parasite. So once infected with this parasite, the host is not able to clear the infection and never can become immune to this disease.
Hence, it is difficult to create a successful vaccine for Trypanosoma brucei.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 6FB
Of the parasitic helminthes discussed in this chapter, the only one transmitted by mosquitoes is Wuchereria.
Wuchereria is a parasite, which causes filariasis. It affects the lymphatic system of the humans.
Humans are definitive hosts and mosquitoes are intermediate hosts. Culex, Anopheles, and Aedes mosquitoes are common mosquito vectors. These mosquitoes have preference for human blood.
Inside the mosquito, the microfilaria changes into moving larvae, which are injected into humans during blood meal. These larvae enter into the blood circulation and enter the lymphatic system. Mainly they affect lower extremities and genital organs.
In endemic areas, the prevention is taken, which focuses against the mosquito bites. Mosquito repellents and using mosquito net during sleep are effective means of protecting from mosquito bites. Hence, the correct answer is Wuchereria.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 6M
Plasmodium vivax matches with (c) schizogony, (G) trophozoites, and (I) hypnozites.
Plasmodium vivax infection occurs in humans when a female anopheles mosquite infected with this parasite bites humans. The sporozoites are injected into the blood circulation during the blood meal and reach liver and undergo schizogony. This stage is called erythrocytic phase, which is outside the erythrocytes.
The merozoites are formed after number of binary fissions. The liver cell ruptures and the merozoites are released into the blood stream.
In some occasions, the sporozoites remain dormant for few weeks or even months. They do not immediately start dividing after entering the liver cell. These are called hypnozoites. The period of dormancy varies for each hypnozoite. The factors which are responsible for sudden triggering of the growth of hypnozoites are not yet known.
When merozoites enter red blood cells, another stage of the parasite is developed called trophozoites. These trophozoites undergo schizogony and produce more merozoites. These merozoites in turn lyse the red blood cells. The red blood cells with this parasite are twice as big as the normal cell. The red blood cells with trophozoites inside are the diagnostic feature of malaria.
Hence, the term Plasmodium vivax matches with (C) schizogony, (G) trophozoites, and (I) hypnozoites.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 6MC
In malaria, the erythrocytic cycle occurs in the red blood cells. The merozoites of the parasite Plasmodium enter the red blood cells, which are called trophozoites. The diagnostic finding of malaria is trophozoites, inside the red blood cells. Trophozoites endocytize hemoglobin of the Red blood corpuscles. Through schizogony, more merozoites are produced and lyse more red blood cells. The erythrocytic lysis takes place cyclically depending on the species of involved plasmodium. Some merozoites develop into gametocytes within the red blood cells whereas most of the merozoites go on in the lysis of new erythrocytes.
Hence, the correct option is (b) Erythrocytic cycle.
The exoerythrocytic phase takes place outside the erythrocytes. During the mosquito bite, the sporozoite stage of the parasite Plasmodium is injected into the body. These sporozoites along with blood stream reach the liver and undergo schizogony over the period of one or two weeks. Due to this, merozoites are formed, which rupture the liver cells and enter the blood stream. The free merozoites penetrate the erythrocyte and then the erythrocytic cycle starts. Hence, the option (a) is incorrect.
The sporogonic phase does not occur in the red blood cells. When the mosquito bites the infected person, the gametocytes present within the red blood cells are ingested by the mosquito. The erythrocytes are digested inside the digestive tract of the mosquito, and the gametocytes are freed. The male gametocytes fertilize the female gametocytes and form zygotes. Then ookinete is formed, which becomes oocyst. This oocyst undergoes meiosis. After a period of ten to twenty days, due to rupture of oocytes, thousands of sporozoites are released. They migrate to the salivary glands of the mosquitoes. Hence, the option (c) is incorrect.
Amastigote phase does not occur inside the erythrocytes in malaria. Leishmania has two stages. One is amastigote, which lack flagella. They multiply inside the macrophages and monocytes of the mammalian host. Hence, the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 6MTF
The given statement is true.
Toxoplasmosis is caused by protozoan parasite Toxoplasma gondii. The primary host is felid. This parasite infects humans and most warm-blooded animals. Transmission of the parasite is through ingestion of feces of infected cat. Cat is the main source of infection for humans, and eating raw pork also contributes to the infection.
Routine investigation for toxoplasma is done for pregnant women. Transplacental transmission of this parasite is very dangerous to the fetus in the first three months of pregnancy.
Some of the effects of toxoplasmosis during pregnancy by the transplacental transmission of the parasite are:
- Spontaneous abortion
- Intra uterine death and still birth
- Congenital anomalies of the fetus including microcephaly
- Inflammation of the retina of the fetus, blindness and anemia.
- Ocular infections can be persistent for many years.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 7CT
Plasmodium causes these signs and symptoms. The symptoms of malaria are fever, chills headache, and vomiting.
Two weeks after the erythrocytic cycle starts, there are enough number of parasites in the blood to cause these symptoms. Hence, the patient had one month history of these symptoms.
Diagnostic sign of malaria is to take the blood smear and it shows the trophozoites inside the erythrocytes.
Treatment depends on the species of the parasite and severity of the disease. The anti- malarial drugs are mefloquine, chloroquine, atovaquone in combination with proguaril.
The WHO (world health organization) prescribes the drug called artemisinin, which is taken from a shrub. This shrub is used in Chinese traditional medicine for malaria. The medication for fever can be given and also blood transfusion can be given if required.
This is not a rare disease in Florida, because the mosquito vectors breed in wet lands.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 7FB
The helminthes, which can directly penetrate the skin of humans to establish infection, are Ancylostoma, Necator and Schistosoma.
Ancylostoma is some species of hookworm. Usually humans are infected by this hookworm by walking with bare foot over contaminated ground. The larvae penetrate the skin and enter the blood stream. Then they enter the lungs and pierce the alveoli and enter the trachea, from where it is swallowed up and carried to the intestine. The point of entry may get an itching patch, which is called ground itch.
Necator is a genus of nematodes. Eggs of these worms are passed along with the stools from the infected human. These eggs hatch up in few days as infective larvae come up. This can live upto five weeks in the soil. These larvae penetrate the human skin and enter the circulatory system.
Schistosoma is trematode called blood fluke. Eggs are passed outside to the environment along with urine or stools. There they enter the intermediate host, snail. The other larval stage of this parasite enters the human host by penetrating the skin.
Hence, the correct answers are Ancylostoma, Necator, and Schistosoma.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 7M
Taenia spp matches with (F) cysticerci.
Taenia saginata is the beef tapeworm and Taenia solium is pork tapeworm. Cattle are the intermediate host of Taenia saginata and pig is the intermediate host of Taenia solium.
Taenia saginata has human as their definitive host. The eggs voided by infected humans along with feces are ingested by cattle and onchospheres are formed in the intestine. This onchospheres enter the circulation of the host, penetrating the intestine and cysticercus bovis is formed in the muscle fibers and in liver or lungs. Humans get infected by ingestion of this cysticercus.
In Taenia solium, in which the humans are definitive hosts, the infection is caused by ingestion of eggs by contaminated water or food. Oncosphers hatch in the intestine of humans and migrates into muscles, brain, or other tissues. Here, they are formed into cysticerci.
If the cysticerci form in the brain tissue, it results in neurocysticercosis. Eggs are ingested by pigs via contaminated food or water. The eggs develop into cysticerci in pig muscles. Humans get infected when they eat undercooked pork with cysticerci. Hence, the term Taenia spp matches with (F) cysticerci.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 7MC
The definitive host for Toxoplasma gonadii is cats. This parasite can reproduce sexually only in cat’s intestine. This protozoan parasite causes toxoplasmosis. The infection with this parasite does not produce any symptoms in healthy individuals. This parasite is transmitted by ingestion of cysts. It is also transmitted from the mother to fetus. In humans it reproduces asexually. All the warm-blooded animals including humans are intermediate hosts.
Hence, the correct option is (b) mosquitoes.
The definitive host of Toxoplasma gonadii is not humans. Humans and other warm-blooded animals are infected by this parasite by ingestion of cysts. By consuming uncooked meat, containing the cysts of parasite or by water and vegetable contamination the humans are infected. The parasite reproduces asexually in human beings. So, humans are intermediate hosts of this parasite. Hence the option (a) is not correct.
The birds are not definitive hosts of Toxoplasma gonadii. Almost all the warm-blooded animals can be infected by this parasite. So, birds can be intermediate hosts of this parasite. Hence, the option (c) is not correct.
Mosquitoes are not definitive hosts of Toxoplasma gonadii. The mosquitoes do not play any part in the life cycle of this parasite. The sexual reproduction of this parasite occurs only in cats and the asexual reproduction occurs in any warm blooded animals like humans, cats, and birds. Hence, the option (d) is not correct.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 7MTF
The given statement is true.
Taenia solium is also called pork tapeworm. Human is the definitive host and pig is the intermediate host. As the infected human passes the eggs in the feces, these eggs are ingested by pigs. These onchospheres hatch and circulate in the musculature of the pigs and humans. Cysticercus develops in the muscles of pigs and humans. By ingesting the infected pork, humans get the infection.
Man becomes the intermediate host of Taenia solium rarely by ingesting the eggs or proglottids. Larvae released from these eggs change into cysticerci in human. That is the dead end of the parasite. This happens accidentally.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 8CT
The diagnosis is Schistosomiasis. This is caused by blood flukes. The name of the species is Schistosoma haematobium.
In this infection, the eggs of the parasite moves into the bladder and ureters, causing hematuria and blockage due to fibrosis and calcification. This may cause bladder cancer in some geographical areas.
Diagnosis is done by the presence of eggs with spines in urine samples. The treatment for blood fluke infection is done by praziquantel. Improved sanitation and avoiding direct contact with the contaminated water can prevent infection.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 8FB
A trematode that can be acquired by eating raw or undercooked food vegetable is Fasciola.
Fluke eggs are passed along with feces or urine from infected people, when those eggs are voided in the fresh water. When this eggs hatch, the larvae called miracidia are released in the water. These larvae enters the snail of a respective species. Cercariae larvae are produced in the snail, as it is intermediate host of the fluke. These cercariae come in contact with humans and penetrate the skin of the host.
In the case of liver and intestinal fluke, cercariae get settled on plants and become encysted metacercariae.
In the case of lung fluke and some of liver and intestinal flukes, the encysted metacercariae are formed inside a second intermediate host.
People get infection by ingestion of metacercariae by eating contaminated raw watercress or other water plants.
Human is the definitive host. After interning the definitive host, the parasite migrates to their respective site in the human body. Hence, the correct answer is Fasciola.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 8M
The term Toxoplasma gondii matches with (B) bradyzoites.
Toxoplasma is a protozoan parasite. This parasite causes toxoplasmosis. In healthy persons, this infection is asymptomatic. In people with weakened immunity, this causes serious illness.
The definitive hosts are cats and the intermediate hosts can be humans or birds or cats.
This parasite has different cellular stages. They are as follows:
- Tachyzoites – quick in multiplying
- Merozoites – divides quickly and multiply the number of parasites inside the definitive host before sexual reproduction.
- Bradyzoites – slow in dividing and forming cysts.
- Sporozoites – multiply asexually to form bradyzoites.
The cat passes out oocysts along with feces. These oocysts survive in the moist soil and gets matured producing sporozoites inside. As the rodents ingest the oocysts, sporozoites are released and enter the rodent’s muscles, digestive organs, brain, and also lymph nodes. Asexual reproduction takes place and sporozoites multiply and bradyzoites are produced. Thick walls are formed around the bradyzoites and form pseudocysts.
For sexual reproduction, the parasite returns to the cat. This is made possible by inhibiting the part of the brain of the rodent that processes the odor and induces fear of the cat. So, the infected rodent is eaten easily by the cat. So, the bradyzoites are released inside the cat’s intestine and complete its sexual reproductive cycle. Hence, the term Toxoplasma gonadii matches with (B) bradyzoites.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 8MC
Tapeworms are transmitted via consumption of an intermediate host. This parasite has mammals as their definitive and intermediate hosts. The definitive host gets this infection by eating and intermediate host as its prey. The eggs of this parasite are ingested through contaminated food and water by the intermediate host. By eating undercooked meat of this intermediate hosts, the cysticercus of this parasite enter the humans, which are definitive hosts. Hence, the correct option is (a) consumption of an intermediate host.
The tapeworms are not transmitted via consumption of the definitive host. The definitive host is human. The infected human passes eggs of this parasite with the feces. The foods contaminated with these eggs are consumed by the intermediate host like pigs. The ingested eggs hatch larvae migrate to the tissue penetrating the wall of the intestine. They develop into cysticercus in muscle. Hence, the option (b) is incorrect.
Tapeworms are not transmitted via vectors such as mosquitoes. Mosquitoes do not have any role in the life cycle of tapeworm. Tapeworm transmitted to the humans via consumption of and intermediate host. Hence, the option (c) is not correct.
Tapeworms are not transmitted via consumption of adult tapeworms. The intermediate hosts like pigs get infected by consuming the contaminated food, which has eggs of the tapeworm. Hence, the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 8MTF
The given statement is false.
Fasciola hepatica can be acquired by eating infected water plants. This parasite is called liver fluke and it infects humans and many mammals. Its distribution is worldwide. Sheep and cattle are killed due to this infection and create big economic loss.
The intermediate host for this parasite is fresh water snail in which the asexual reproduction takes place. The eggs are passed along the feces of infected mammals and humans. These eggs hatch into miracidia in warm conditions. The miracidia find snail host. Small cercariae come out of snail host and encyst as metacercariae on the water plants. Sometimes humans eat uncooked water cress. Thus, the parasite gets ingested by humans sometimes.
Hence, the correct statement is “Fasciola hepatica can be acquired by eating infected water plants.”
Microbiology with Diseases by Taxonomy Chapter 23 Answers 9CT
In rare occasions, humans become intermediate hosts of Taenia solium if the eggs or gravid proglottids are ingested by humans rather than cysticerci.
The larvae from the eggs are changed into cysticerci in the muscle of the humans. This happens when the humans become intermediate host accidentally.
This is the dead end of the parasite, because no host will eat human flesh. So, humans with cysticerci are the dead end of that parasite.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 9FB
Hookworm disease is caused by Ancylostoma in the Middle East.
This disease is called anchylostomiasis. This sucks blood from the humans from the walls of the intestine. If the hook worm is present in huge numbers, it will cause iron deficiency anemia.
Ancylostoma duodenale is one of the hookworms, which infect the humans. They are distributed throughout the Americas, Africa, the Middle East, North Africa, and southern Europe.
The other hookworm is Nacator Americans. It is mostly seen in the Americas and Australia.
The eggs of both of these worms are not distinguished. The eggs are deposited in the soil and hatch into larvae, which in turn change into an infective larvae. This larva penetrates the human skin and enters the humans.
By improved sanitation and education and using footwear can reduce the risk of infection. Therefore, the correct answer is Ancylostoma.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 9M
Trypanosoma matches with (J) Trypomastigotes.
Trypanosoma is a flagellate protozoan.
In the case of Trypanosoma cruzi, Chagas’ disease is caused. Transmission of the parasite is through the kissing bug. Inside the hind gut of the bug, the epimastigote of the parasite is changed to trypomastigotes. These trypomastigotes are voided along with the feces of the bug in the site of the bite. When the host scratches the itchy wound made by the bug, the trypomastigotes enter the body through the wound and enter the blood circulation. Then they enter the heart muscle cells or macrophages.
In the case of Trypanosoma brucei, African sleeping sickness is produced. Transmission of this parasite is through tsetse fly. Inside the salivary gland of the tsetse fly, the epimastigote of the parasite matures into trypomastigotes, which are infective. During the blood meal, trypomastigotes are injected into the blood circulation and lymphatic circulation. Some enter the central nervous system (CNS).
Hence, the term Trypanosoma matches with (J) trypomastigotes.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 9MC
The parasite that cannot be killed by routine boiling or other than cryptosporidium is Giardia. Giardiasis is a waterborne gastrointestinal disease. It has very hard protective cover and can survive in the environment for months. As it cannot be killed by routine boiling, filtering water is necessary to remove this parasite from the drinking water. Hence, the correct option is (a) Giardia.
Trypanosoma brucei cause African sleeping sickness and Trypanosoma cruzi causes Chagas disease. Transmission occurs through tsetse fly and kissing bugs. This parasite is transmitted via vectors. So, the option (b) is incorrect.
Toxoplasma is a protozoan parasite. This parasite is transmitted by consuming raw or undercooked food contaminated with cysts of this parasite. Water and vegetables contaminated with oocysts cause infection. Prevention is to cook the meat thoroughly or deep-freeze meats. Hence, the option (c) is incorrect.
Plasmodium belongs to Apicomplexan parasites. This parasite causes malaria. This disease is transmitted by mosquito bites. There are two hosts for this parasite. It is a vector- mosquito and a vertebrate host. Hence, the option (d) is not correct.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 9MTF
The given statement is true.
Snails are intermediate hosts of schistosomiosis parasite and humans are definitive hosts. In developing countries people use water contaminated with snails. Poor sanitation facilities are also a cause of this infection.
In endemic areas, as technology has improved and economy is also stabilized, the incidence of schistosomiosis has also been increased because water reservoirs and improved irrigation system has become a habitat for the snails, which are intermediate hosts of this parasite.
The cercariae escape from the snail into the water. When humans come in contact with the water, it penetrates the skin. The larvae enter into the blood circulation. Here the sexual reproduction takes place. The eggs have distinctive spines. The eggs enter the intestine or urinary bladder and ureters; and are passed outside along with stools or urine.
This parasite produces chronic infection if the eggs lodge in the liver, brain or lungs. Eggs, which are trapped in those tissue die there and cause fatal tissue damage.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 10FB
Enterobius vermicularis and Wuchereria bancrofti are the two parasites demonstrating nocturnal movement, which is important for diagnosis.
Enterobius vermicularis is called pin worm. It’s only host is humans. The mating takes place in the large intestine. The female pinworm comes to the anal area during nights and lays their eggs around the anus. Due to this, scratching is intense around the anal area and bacterial infection may form as secondary infection. So, if the patient complains of intense itching sensation around the anus during nights this is the diagnostic symptom of Enterobius vermicularis.
Wuchereria bancrofti is filarial parasite. It causes filariasis by infection of lymphatic system. Chronic filariasis is called elephantiasis. Humans are definitive hosts and mosquitoes are intermediate hosts. The microfilarial larvae of this parasite live in blood circulation. During day time, it lives in the deep veins and during nights it comes to the peripheral circulation, so that the mosquito vector can be ingested with these larvae during blood meal. This coincidence with the nocturnal feeding habit of the vector is a diagnostic sign of this parasite infestation.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 10M
The term Wuchereria bancrofti matches with (D) microfilaria.
This is a parasitic nematode. This is transmitted by mosquito vectors. This infects the lymphatic system of the vertebrate host and causes filariasis. This can produce chronic disease called elephantiasis.
The first stage larvae are called microfilariae and they move freely in the blood circulation. In the day time, they are in the deep circulation and during the nights they come to peripheral circulation. This nocturnal periodicity coincides with the feeding habit of the vector.
Then it is ingested by the mosquito during the blood meal and matures into juveniles larvae and migrates into the salivary glands of the mosquito. During the next blood meal, it infects the new host. Hence, the term Wuchereria bancrofti matches with (D) microfilaria.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 10MC
The immature fluke stages that infect small intermediate hosts are called miracidia. They are free living larvae. These miracidia hatch within 24 hours and enter the host, snail. They complete two or three asexual reproductive cycles in the intermediate host to become cercaria larva. The cercariae larva leaves the snail host and enters the new host. Hence, the correct option is (d) miracidia.
Metacercariae is encysted cercariae of the fluke. In lung flukes, intestinal and liver flukes, the cercariae encyst within a second intermediate host and become metacercariae. Humans ingest the metacercariae and get infected. Hence, the option (a) is not correct.
Cercariae do not infect small intermediate host. Miracidia infect the small intermediate host. Miracidia after the asexual reproduction become cercariae. These cercariae form a cyst and become metacercariae on vegetation in the case of some intestinal and liver flukes. In some cases of intestinal and liver flukes, metacercariae is formed in second intermediate host. Hence, the option (b) is not correct.
Cysticerci are not the immature fluke stage. It is larval stage of tapeworm. The larvae of Taenia solium causes an infection called cysticercosis. They form cysts in brain and muscles. These cysts are called cysticerci. Hence, the option (c) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 10MTF
The given statement is true.
Wuchereria bancrofti is a parasite, transmitted by mosquitoes and cause lymphatic filariasis. They enter the lymphatic system and the lymph nodes. Adult parasites live in the lymphatic system and reproduce up to seventeen years. During the day time, the larvae stay in the capillaries of the organs and during night time they come to the blood circulation and swim freely. Thereby it coincides with the feeding habit of the mosquito, suitable for transmission.
Damage to the lymphatic system occurs as the disease progress. As the lymphatic vessels are getting blocked there will not be enough drainage of lymph fluid. The areas where the lymph is accumulated, tissues start to enlarge and harden.
Chronic infection causes elephantiasis, in which the parasite lodges inside the lymphatic system. This infection affects mostly lower extremities. It can also affect arm, vulva, breasts, and scrotum.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 11MC
The beef tapeworm is known as Taenia saginata. This parasite lives in both humans and cattle. Humans are definitive host and intermediate host is cattle. The infected humans pass the fertilized eggs along with faeces. These eggs are ingested by cattle and the zygotes are formed as the thick shell of the egg is digested by the digestive enzymes. These zygotes or oncospheres enter the circulation of the cattle. In the circulation, the fluid filled cysts are formed. Cysticercus bovis are the cysts formed in the muscle fibers and also in lungs and liver. By eating undercooked or raw food, humans get this infection. Hence, the option (b) is correct.
Taenia solium is not beef tapeworm. It is pork tapeworm. It has two hosts namely pig and humans. The larvae of this parasite cause cysticercosis in humans. When an infected human passes faeces, the eggs are also shed along. Pigs and other humans get infected by the ingestion of eggs due to contamination. The ingested eggs hatch into oncospheres, which migrate from the intestine and enter the striated muscles, brain, liver, and other tissues also. Here the cysticercae are formed. Hence, the option (a) is incorrect.
Ancylostoma duodenale is not the scientific name of beef tapeworm. It is called hookworm. The hosts of this parasite are humans, cats, and dogs. The filariform larvae penetrate the skin of the host and enter the blood circulation and reach the lungs. It is then coughed up, swallowed, and goes into the digestive tract to the small intestine. Infection with this parasite causes abdominal pain, and loss of appetite. In severe cases, it causes anemia, and protein deficiency. Hence, the option (c) is not correct.
Echinococcus granulosus is not the scientific name of beef tapeworm. It is called hydatid worm. The definitive host is dog. The intermediate hosts are humans and cattle. The infection of the parasite is called hydatid disease. Hence, the option (d) is not correct. Hence, the correct option is (b) Taenia saginata.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 12MC
Enterobius vermicularis is commonly called pinworm. The other name is threadworm. It is a parasite in the small intestine of humans. The infestation of pinworm is called enterobiasis. The mode of transmission is human to human by ingestion of eggs. Dust contaminated with these eggs are airborne and are inhaled and swallowed up. The symptoms due to this infestation are itching around the anal area. Hence, the option (b) is correct.
Hookworm is not the common name of Enterobius vermicularis. It is the term for the Ancylostoma duodenale and Necator americanus. It lives in the small intestines of mammals like human, dog, and cat. Hence, the option (a) is not correct.
Whipworm is not the common term used for Enterobius vermicularis. The roundworm is otherwise called whipworm due to its appearance. It has scientific name Trichuris trichura. Trichuriasis is caused when the parasite infects the large intestine of human beings. Whipworm infestation is common in individuals who are infected with Giardia, Ascaris, and hookworms. Hence the option (c) is incorrect.
Tapeworm is not the common name used for Enterobius vermicularis. The scientific name of tapeworm is Taenia solium. These parasites look like a tape and hence got this name. It has mammals as their definitive host and intermediate hosts. The eggs are ingested by contamination of food and water. Hence, the option (d) is not correct. Hence, the correct option is (b) Enterobius vermicularis.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 13MC
The infective larvae of Necator americanus larvae must pass through human lungs to mature. This parasite lives in the small intestine of hosts. The hosts are humans, cats, and dogs. The unembryonated egg of the parasite becomes embryonated under favorable conditions and hatches. The first stage is called rhabditiform larvae. The second stage molts and third stages larvae are called filariform larvae. This is infective form. This larval from enters the human body by penetrating the skin. It enters the blood circulation and enters the heart and reaches the lungs. Inside the lungs, they enter the alveoli and goes to trachea. From there it gets swallowed up and goes to the small intestine to mature. Hence, the option (c) is correct.
The infective larvae of Necator americanus do not pass through bladder to mature. After penetrating the human skin it enters the circulation and enters the lungs. Then it reaches the digestive tract from the trachea. The larvae attach to the small intestine and mature into adults. Hence, the option (a) is incorrect.
The infective larvae of Necator americanus do not pass through brain to mature. It passes through the lungs to small intestine where they mature. Hence, the option (b) is not correct.
The filariform larvae do not go through the liver. It goes through the lungs and heart along the blood circulation. They burrow through the alveoli and enter the trachea. The larvae mature in the small intestine. Hence the option (d) is incorrect. Therefore, the correct answer is option (c) Necator americanus.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 14MC
Both Plasmodium species and Wuchereria bancrofti are carried by mosquitoes in the genus anopheles. In endemic areas Plasmodium species cause malaria in humans. This Anopheles gambiae mosquitoes are vectors of dangerous malarial parasite called Plasmodium falciparum. Filariasis is caused by Wuchereria bancrofti. Some species of Anopheles mosquitoes are vectors of this parasite and serve as intermediate host of this parasite. Hence, the option (b) is correct.
The Aedes mosquitoes are not the carriers of the Plasmodium species. Aedes mosquitoes are one of the vector species which carries the parasite Wuchereria bancrofti. They have preference for human blood and only humans are infected with this parasite. Aedes mosquitoes are not vectors of Plamodium species. Hence, the option (a) is not correct.
Culex mosquito is not the vector of plasmodium species. But it is carrier of the parasite Wuchereria bancrofti. Female culex mosquitoes ingest the microfilaria during the blood meal. These microfilariae develop inside the mosquito and become larvae. These larvae migrate to the salivary glands and get injected to the next human whom the mosquito bites. Hence, the option (c) is not correct.
Ctenocephalides is not the vector of the plasmodium species and Wuchereria bancrofti. It is a type of flea. There are dog fleas and cat fleas. They breed on dogs and cats. They are blood sucking insects. Hence, the option (d) is not correct. Hence, the correct option is (b) Anopheles.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 15MC
The arthropods responsible for transmitting most of the parasitic diseases are mosquitoes. An arthropod means animal with segmented body, legs with joined segments, with hard external skeleton. The mosquitoes serve as vectors or carriers of many parasites. Some act as hosts of those parasites. They are called biological vectors. These mosquitoes are seen with the host during their blood meal only. The mosquitoes are responsible for spreading malaria and filariasis. Hence, the option (c) is correct.
Fleas are not responsible for transmitting parasitic diseases. They are parasites, which pierce and suck the blood of the host. They are external parasites and also wingless insects. They live on dogs, cats, and human beings. Hence, the option (a) is not correct.
Ticks are responsible for transmitting few parasitic diseases, not most of them. Ticks harbor many diseases causing pathogens difficulty to diagnose. Ticks serve as vector for Babesia microti and causes Babesiosis. This disease is spreading widely as its vector tick has expanded range because of global warming. Hence, the option (b) is not correct.
True bugs are called Hemiptera. They are not responsible for transmitting most of the parasitic diseases. Many species of these bugs are pests of crops. Hence, the option (d) is not correct. Hence, the correct option is (c) mosquitoes.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 16MC
Majority of the cestodes are transmitted via ingestion. Cestodes are also called tapeworms. They live in the digestive tract of vertebrates. Humans are infected by consuming undercooked pork or beef having the cysts of these parasites. The infected human passes eggs along with faeces, which are ingested by grazing animals like cow. These are intermediate hosts and humans are definitive host. Hence, the option (a) is correct.
The majority of the cestodes are not transmitted by vectors. Vectors make a pathway for pathogen to get into the host. This may be done by means of blood sucking. The vectors are not affected by the pathogens, but it transmits the pathogen from one host to other host, thereby successfully transmitting the diseases. In the case of cestodes, the transmission is by the ingestion of eggs or consuming meat having the larvae of the parasite. Hence, the option (b) is wrong.
Most of the cestodes are not transmitted by direct contact, but by ingestion. The cestodes have definitive and intermediate host. Many species of this parasite infect humans after getting consumed by them with undercooked food. Hence, the option (c ) is not correct.
Most of the cestodes do not get transmitted by inhalation. Hence, the option (d) is not correct. Hence, the correct answer is option (a) ingestion.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 17MC
To prevent infection by Giardia, the effective method is to drink only bottled water. Giardiasis is a waterborne gastrointestinal disease, which is commonly seen. Giardia lives in the small intestine of the humans and animals. The mode of transmission is fecal-oral route. It is mainly water contamination with cysts of the parasite. Cysts are hardy. This parasite is found in water, food, and in soil, which are contaminated with feces. Due to the protective outer layer of the shell, this organism can live for months outside the host in the environment. So, water should be sterilized chemically or filtered. Boiling is not sufficient because cysts can survive boiling. So, purified bottled water is an effective way of preventing Giardiasis. Hence, the option (b) is correct.
Sexual abstinence is not the most effective in prevention of Giardiasis. The parasite is transmitted by fecal-oral route. So, one should avoid contact with feces during sexual intercourse to prevent the infection. Hence, the option (a) is not correct.
Use of insect repellent is not the effective prevention of Giardiasis. There is no chemoprophylaxis. The transmission route is fecal-oral. So, insect repellant cannot help in the prevention of Giardia infection. Hence, the option (c) is not correct.
Cooking all food is not the effective prevention of Giardiasis. Giardiasis is waterborne disease. Cysts of this parasite can withstand boiling. In endemic areas, filtered water should be used for cooking and washing the utensils, which are used for eating. Hence, the option (d) is not correct. Hence, the correct option is (b) drinking only bottled water.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 18MC
The sporogenic phase of Plasmodium occurs in Anopheles mosquito. As the mosquito takes the blood meal from humans, it ingests gametocytes present inside the red blood cells. The gametocytes are released from the red blood cells in the digestive tract of mosquitoes and the gametes are formed. The zygotes are formed after the fertilization of female gametes by male gametes. The zygote changes into ookinete, which in turn changes into oocyst in the mosquitoes’ gut wall. This oocyst undergoes meiosis and releases thousands of sporozoites after the rupture of the cystic wall. These sporozoites enter the salivary glands of the mosquitoes. These are transmitted to a new host during the blood meal. Hence, the option (d) is correct.
The sporogenic phase of Plasmodium does not occur in red blood cells. It occurs in Anopheles mosquito. The erythrocytic cycle occurs in red blood cells. The merozoites which are free swimming in the blood circulation enter the erythrocytes. After entering inside the red blood cells, it changes into trophozoites. The trophozoites endocytize the hemoglobin protein present in the red blood cells. The diagnostic sign of malaria is the presence of trophozoites inside the red blood cells. More merozoites are produced from the trophozoites by schizogony. Merocytes destroy the erythrocytes and thus continues the life cycle. Hence, the option (a) is not correct.
Liver cells are not the site for sporogenic phase of Plasmodium. The infected female Anopheles mosquito injects sporozoites into the blood stream of humans. These sporozoites enter the liver and schizogony takes place inside the liver cells. Merozoites are produced as a result of schizogony. These merozoites rupture the liver cells and enter the blood circulation. Hence, the option (b) is not correct.
Schizonts contain merozoites. These are oval or round in shape. The sporogenic phase of Plasmodium does not occur in the schizonts. Hence, option (c) is not correct. Hence, the correct option is (d) Anopheles mosquito.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 19MC
The tapeworm attachment organ is scolex. It is a small organ having suckers and hooks. The main function of scolex is anchorage. The tapeworm gets attached to the tissues of the host by this scolex. It is the anterior end of tapeworm. Hence, the option (a) is correct.
Proglottid is not the attachment organ of tapeworm. Body segments are called proglottids. The neck is present behind scolex. Segments of the body are attached from the neck continuously. New proglottids displace the older ones away from the neck. When the proglottids get mature, male and female reproductive organs are produced in them. Proglottids are monoecious. The proglottids filled with eggs are often shed along the feces. Hence, the option (b) is not correct.
Strobila is not the organ for attachment in tapeworm. The body segments called proglottids look like a chain. This chain of proglottids is called strobila. The strobila shows the order of development. The proglottids present near the neck are immature and towards the middle of the chain are mature and the proglottids near the posterior end are gravid with fertilized eggs. Hence, the option (c) is not correct.
Cuticle is not the attachment organ of tape worm. Cuticle is the outer skin of the tapeworm. The nutrients are absorbed through the cuticle. There is not mouth for the tapeworm. Hence, the option (d) is not correct. Hence, the correct option is (a) scolex.
Microbiology with Diseases by Taxonomy Chapter 23 Answers 20MC
Trophozoite-cyst conversion is vital to the life of Balantidium, Entamoeba, and Giardia. In all these protozoans these two stages of life cycle is present. Trophozoites are released from the cystic wall after ingestion by the host. These trophozoites undergo encystment and form cysts, which are infective. Hence, the option (d) is correct.
In Balantidium, life cycle has two stages of development called trophozoite and cyst. Infection takes place by the ingestion of cysts. After reaching the small intestine trophozoites are produced. In the large intestine, the trophozoites are colonized and feed on the intestinal flora. Encystment takes place in the distal part of the large intestine or outside the body in feces. The trophozoite-cyst conversion is not only in Balantidium, but also in other protozoan parasites. Hence, the option (a) is not correct.
Entamoeba life cycle also has two stages. The trophozoites in the large intestine feed on bacterial flora and undergo binary fission. Encystation occurs. Cystic stage is formed which is used in the transmission of the parasite. The trophozoite-cyst conversion is not only in Entamoeba. Hence, the option (b) is not correct.
Giardia has two stages in its life cycle. They are active trophozoites and infective cyst. After the ingestion of cysts the trophozoites are released and remain in the lumen of small intestine. Then they move towards the large intestine where encystment takes place. The cysts are infective. There are other protozoans, which have trophozoite-cyst conversion in the life cycle. Hence, the option (c) is not correct. Therefore, the correct answer is option (d) all of the above.