Microbiology with Diseases by Taxonomy Chapter 14 Answers
Microbiology with Diseases by Taxonomy Chapter 14 Answers 1CM
The following terms are given in the question:
- Contact transmission
- Direct contact
- Droplet transmission
- Indirect contact
- Vector transmission
- Vehicle transmission
The concept map for the transmission of diseases is given below:
Microbiology with Diseases by Taxonomy Chapter 14 Answers 1CT
A menopausal woman, Mrs. E might have developed gingivitis from normal microbiota.
The onset of menopause might show some symptoms in some women. Some of the symptoms include:
- Hot flashes
- Night sweats
- Irregular menses
- Increased stress
- Mood changes
Due to the above symptoms, the immune system of Mrs. E might have weakened. This might have caused the normal flora of the mouth to turn into opportunistic pathogens.
When these normal flora turn into pathogens, they cause diseases only in the persons with low immunity. In healthy normal individuals, normal flora does no harm to the host.
In the case of Mrs. E, it might be due to the weakened body, which allowed this normal flora to infect her.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 1FB
A microbe that causes disease is called a pathogen.
There are different types of microbes. The different groups are given below:
- Those that live in a relationship with other organisms
- Normal flora
- Opportunistic pathogens
- Disease causing microbes
- Those that live in a relationship with others:
The relationships of mutualism, parasitism, and commensalism come under this category. In mutualism, both the organisms will be benefited, whereas in parasitism, only one organism gets benefit while the other is harmed. In commensalism, one organism will get benefit while the other is unharmed.
- Normal flora:
The normal flora are the organisms, which are always present on our body. They do not cause any harm and protect the body from pathogens. Some microbes also synthesize vitamin K, which is used by the human body.
- Opportunistic pathogens:
Some normal flora become opportunistic pathogens when the immunity of the host becomes low. These microbes use the opportunity and cause infection or disease.
- Disease causing microbes:
Disease causing microbes are called pathogens. Their nature is to always infect and destroy host cells. Such microbes are usually highly virulent and cause disease in some host or the other.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 1L
- The first diagram shows that the disease is endemic. Since the cases are spread far and wide, it can also be termed as sporadic. A disease is said to be endemic when it occurs continually for a specific population or in a specific area.
- The second diagram shows that the disease is epidemic. Since the cases are concentrated in one area, it is an epidemic. In epidemic a disease occurs at a greater frequency than expected in a specific area or population.
- The third diagram shows that the disease is pandemic. Since the cases are concentrated in different parts of the hemisphere and are seen in many parts of the hemisphere, it is called a pandemic.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 1MC
- An interaction in which both members benefit is known as mutualism. Termites, which eat wood, cannot digest the cellulose in the wood without the presence of specific protozoa and bacteria in their bodies. The termites provide a home and food to the bacteria while the bacteria share the nutrients obtained from the wood with the termites. Hence, the correct option is (a) mutualism.
- An interaction in which one partner gains the benefit while the other partner is harmed or injured is known as parasitism. In some cases, the host is killed. An example would be Tuberculosis bacilli in the lungs of humans. The bacilli are benefitted as they gain nutrients and reproduce. But, the human hosts are harmed as their respiratory system is damaged due to the presence of the bacilli. Hence, the option is (b) is incorrect.
- Commensalism is a type of interaction, one partner benefits while the other partner is not affected at all. An example would be the presence of Staphylococci on our skin. The bacteria benefit by absorbing nutrients and growing on the skin of humans. The humans are not affected by this interaction. Hence, the option is (c) is incorrect.
- Pathogenesis is not a type of interaction at all. Pathogenesis is the method of infection a parasite uses. If the lifecycle of the parasite takes place in the host, this also comes under pathogenesis. All the activities of the parasite from entry to exit from the host come under pathogenesis. Hence, the option is (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 1SA
The three types of symbiotic relationships are given below with an example for each:
An interaction in which both members benefit is known as mutualism. Termites, which eat wood, cannot digest the cellulose in the wood without the presence of specific protozoa and bacteria in their guts. The termites provide a home and food to the bacteria while the bacteria share the nutrients obtained from the wood with the termites.
An interaction in which one partner gains benefit while the other partner is harmed or injured is known as parasitism. In some cases, the host is killed. An example would be Tuberculosis bacilli in the lungs of humans. The bacilli are benefited as they gain nutrients and reproduce. But, the human hosts are harmed as their respiratory system is damaged due to the presence of the bacilli.
In this type of interaction, one partner benefits while the other partner is not affected at all. An example would be the presence of Staphylococci on our skin. The bacteria benefits by absorbing nutrients and growing on the skin of humans. The humans are not affected by this interaction.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 2CT
Mr. W died of an E. coli infection after his intestine has punctured. This microbe usually lives in the intestine where it causes no harm.
Microbial flora are those organisms, which permanently live in specific sites in our body. These microbes usually do not cause any harm to the host. They maintain a commensal relationship with the host and leave the host unharmed. When these microbial flora are inserted into another site apart from the usual site, they can cause disease.
In the above case, the intestinal puncture in Mr. W resulted in the bacteria of the intestine spilling out. Since E. coli is usually present in colon, once it leaves the colon, it functions as a pathogen rather than a normal commensal.
So, the intestinal puncture enabled the E. coli from the colon to spread to other parts of the body and cause infection. Thus, Mr. W died of an E. coli infection.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 2FB
Infections that may go unnoticed due to the absence of symptoms are called asymptomatic or subclinical infections.
In some infections, there is an absence of symptoms. This does not indicate that the person is healthy. A person who feels healthy can be correctly diagnosed, if the correct tests are performed. This infection in which there is a lack of outward symptoms is called an asymptomatic or subclinical infection.
In infections like leukocytosis, the person does not have any symptoms. But, if the blood of the person is tested correctly, the diagnosis will show the disease. In diseases like AIDS, a long period occurs without any symptoms.
The people who are asymptomatic can also spread diseases. When a person is asymptomatic, the person can transfer bacteria without knowing. In the example of Typhoid Mary, she was asymptomatic, but spread the disease of typhoid to many people around her. When she was tested, she was found to be positive, but asymptomatic.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 2MC
- An axenic environment is an environment that contains only one species. If there are many species of bacteria or microorganisms it is not called an axenic environment. Hence, the correct option is (b) contains only one species.
- An axenic environment does not exist in the human mouth. An axenic environment is an environment that contains only one species. Since there many species of bacteria present in the mouth, it does not possess an axenic environment. Hence, the option (a) is incorrect.
- An axenic environment does not exist in the human colon. Since there are about 106 million bacteria in the human colon and of different species, the human colon does not contain an axenic environment. Hence, the option (c) is incorrect.
- The option of (a) and (c) cannot be right. The two options are mouth and human colon. Both these places have a large variety of bacteria. In the human colon, even the number of bacteria is very high. Since both these places possess a large variety of bacteria, the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 2SA
The three conditions that create opportunities for pathogens to cause disease in humans are:
- Introduction of a species of normal flora into an unusual site in the body:
Normal flora are the species of microbes present in different parts of the body. Each part of the body has its own special flora.
- Immune suppression:
Some conditions suppress the immune system. Conditions like disease, malnutrition, old or young, physical stress, emotional tensions, chemotherapy patients, radiation patients, usage of immunosuppressants in AIDS (Acquired immuno deficiency syndrome) patients and patients with a transplant can all face the problem of immune suppression.
- Changes in the normal microbiota:
When changes occur in the microbial flora in a specific part of the body, it also gives a chance for a specific species to become an opportunistic pathogen. When women take antibacterial drugs for any other infection, the bacterial species in the vagina is also wiped out. This enables a species of yeast to proliferate. This causes an yeast infection.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 3CT
In the graph, we could see the epidemic of two diseases, which affect the patient for only one day. Neither the blue disease nor the red disease is treatable and doesn’t need treatment. In the graph, we see that both the epidemics begin at the same time.
The epidemic, which affected more people during the first 3 days is the red epidemic. The curve of the red line goes high into the graph which indicates that many people were affected by the red epidemic. In contrast, we see that the blue epidemic does not rise high in the graph like the red epidemic.
The short time course is seen in the red epidemic. We see that in 5 days, the red epidemic subsides. But, in the case of the blue epidemic, we see that it continues for 12 days. This difference in the course of the disease might be due to the short incubation period of the red epidemic.
When the incubation period of a disease is less, the other stages like prodromal period, illness, decline, and convalescence follow quickly. The incubation period of the red epidemic might be shorter than the incubation period of the blue epidemic. This would enable the red epidemic to affect more people in a short span of time.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 3FB
The study of the cause of a disease is etiology.
It is important to find out the cause of a disease because all diseases are not caused by infections. The different causes of diseases are:
Some diseases are transferred from mother to child in the process of vertical transmission. These diseases are transferred through genes. They are passed from one generation to another.
These diseases are acquired at the time of birth. They can be due to genetic or environmental causes. They also can be defects during the process of development of the baby.
These diseases are seen in the aged where it is a sign of slow degeneration. These diseases arise due to the wearing out of tissues and bones.
Some diseases may arise due to nutritional deficiencies. Some maybe vitamin deficiencies like rickets, kwashiorkor. This usually happens when the vitamins are deficient in diet.
These diseases arise due to either less or too much secretion of the hormones of the body. In the example of thyroid hormones, the two types of hormonal imbalances are hyperthyroidism and hypothyroidism. Some of these defects can be rectified by taking supplements.
These diseases can arise by mental tensions. The tension in the mind can give rise to rashes and other outward symptoms. Some other symptoms would be gastrointestinal distress and improper digestion.
These diseases can arise by the activity of the immune system. Sometimes, the immune system acts in a hyperactive way. These reactions are called hypersensitivity reactions. A few examples are Arthus reaction, hay fever, asthma and autoimmune diseases.
Any neoplastic growth can cause some kind of symptoms. As the tumor starts growing, it exerts pressure on the surrounding cells and tissues. Neoplastic growth can be benign or cancerous. Benign tumors usually grow slowly and do not cause much harm. Cancers, on the other hand can spread to other parts of the body.
These infections are caused by infection by pathogens. These pathogens usually infect and destroy host cells. Different pathogens cause different symptoms.
These infections are physician induced infections. When a doctor uses instruments which are not properly sterilized, it allows the microbes to infect the patient. Since patients in hospitals have low immunity, microbes can easily infect them. Even things like cotton and gauze should be sterilized.
These diseases do not have any known cause. The symptoms do not have any known cause. Two examples would be Alzheimer’s disease and multiple sclerosis.
These diseases are those, which are acquired by health care workers. They can acquire these infections from the hospital surroundings or from patients themselves. One example would be Pseudomonas infection in a patient with burns.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 3MC
Out of the following statements, the explanation to show whether they are true or not is given below.
- “Contaminants may become opportunistic pathogens.” The statement given in option (a) is true. Contamination by microbes is the mere presence of microorganisms on the surface. These contaminants include residents and temporary members. When the immunity of the individual becomes low or when the opportunity arises, these contaminants can become pathogens.
- “Most microbial contaminants will eventually cause harm.” The statement given in option (b) is false. There are many microbes on the surface of our skin. These microbes do not harm us. Instead they protect us from pathogens which try to settle on our skin. Some microbes inside our body produce vitamin K, which is needed for our body.
- “Contaminants may be a part of the transient microbiota.” The statement given in option (c) is true. The contaminant microbes might be a part of the microbiota present in or on our body. There are a large variety of microbes, which are present as normal flora in our body. Microbial contaminants can be a part of the normal flora.
- “Contaminants may be introduced by a mosquito bite.” The statement given in option (d) is true. Yes, contaminants can be introduced by a mosquito bite. When a mosquito bites, it creates an opening in the skin. This small opening is enough for the contaminants of the skin to enter the wound. Hence, the false option is (b).
Microbiology with Diseases by Taxonomy Chapter 14 Answers 3SA
The three portals through which pathogens can enter the body are:
The skin usually is a barrier to most microbes. But some microbes can use the natural openings of the skin like the hair follicles and the sweat glands. Other man-made openings like cuts, abrasions and wounds also serve as a portal of entry for microbes. Some species of fungi can digest the top layers of the skin and infect the body.
- Mucous membranes:
This is the major portal of entry for microbes. There are many mucous membranes which are exposed to the outside environment. Some of them are respiratory, gastrointestinal, urinary, reproductive, and the conjunctiva. Since the mucous membranes are soft and living cells, it is easier to microbes to enter the body through this portal. Out of the different mucous membranes exposed to the outer atmosphere, the respiratory tract is the most used route for many microbes.
The placenta is the connection between the baby and the mother. It is useful in the exchange of wastes and nutrients between the baby and the mother. Most of the pathogens find the placenta a formidable barrier. But for some pathogens, the case is different. They can cross the placenta and infect the embryo.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 4CT
A young female of 27 years, consulted her doctor regarding symptoms of rash, fever, malaise, and muscle pain. She had also suffered from headache three days before these symptoms appeared. She also added that she had been bitten by a tick a week prior to the onset of the headache.
Her physician diagnosed Rocky Mountain spotted fever (RMSF) and gave her tetracycline. It took two days for the symptoms to subside, but she continued the antibiotic for 2 weeks.
The graph showing the course of the disease with the relative number of pathogens and the different stages of the disease is given below:
Microbiology with Diseases by Taxonomy Chapter 14 Answers 4FB
The study of where and when diseases occur and how they are transmitted within populations is epidemiology.
Epidemiology is the study where the pattern of a disease is studied along with the effect on the health of the general population. It also studies how the disease is transmitted from one person to another. The mode of infection of the disease is also studied.
Basing on the studies of epidemiology, preventive medicine can also be found. Necessary treatment is also needed for the patients. The risk factors like age or sex are also screened. The collection of all these types of data is needed.
The various types of data is collected and compared statistically. Even clinical trials come under the field of epidemiology. In such trails, a specific drug is given and the effect is observed in a group of people.
Sometimes, the course of the disease is studied. Some diseases like whooping cough have different and distinct stages. These can be identified and contagious patients can be separated.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 4MC
- The respiratory tract is the most frequent portal of entry for microorganisms. The respiratory tract has some defenses like cilia and mucous production in the trachea and hair in nostrils. Despite all these defenses, microbes find easy to overcome these barriers and cause infections. The frequency of colds, coughs and other respiratory infections are much higher than the infections of other parts of the body. Hence, the correct option is (a) the respiratory tract.
- The skin is the primary line of defense of the body. Microorganisms usually cannot penetrate the skin unless there are gashes and cuts. The skin has sebum secretions, which keep the skin waxy and prevent infections. In addition, the normal flora of the skin prevents pathogens from attacking the skin. Hence, the option (b) is incorrect.
- The conjunctiva is present in the eye. The secretions frequently wash the eye and keep it sterile. The fluid in the eye prevents the growth of microbes. Since the conjunctiva is a mucous membrane with living cells, it can be a target for the entry of pathogens. Hence, the option (c) is incorrect.
- A cut or wound is one of the methods by which pathogens can enter the body. When a cut or wound occurs in the skin, it gives the skin microorganisms a chance to enter the body. Since a cut or wound is an infrequent event, it is not the frequent portal of entry for microorganisms. Hence, the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 4SA
The four postulates of Koch are given below:
- The suspected agent must be present in every case of the disease.
- The agent must be isolated and grown in pure culture.
- The cultured agent must be able to cause the same disease when it is inoculated into a healthy host.
- The same agent must be reisolated from the same host which was injected with the agent.
The exceptions are:
- Some microbes cannot be cultured in the laboratory. One example would be Mycobacterium leprae.
- Some diseases are not caused by the pathogen alone. A combination of factors such as physical or genetic factors along with the pathogen is necessary for the disease.
- For diseases which infect only humans, the third postulate cannot be followed. Humans cannot be purposely infected with pathogens.
- Some conditions like hepatitis can be caused by many viruses. It would then be difficult to experiment with all the viruses.
- Some pathogens were ignored at the time Koch’s postulates were given. Now, the real causes of some diseases are being discovered.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 5CT
After a visit to the local water park, over 30 children below the age of 3 developed gastroenteritis. The percentage of the sick children was about 44% of the total number of people who visited the park that day. Only children below 3 years were affected while older children and adults were unaffected. The causative agent was determined to be Shigella.
Based on the information given in the question, we can classify the outbreak as an epidemic. An epidemic is an infection or a disease, which occurs at a greater than normal frequency. Hence, the above situation is an epidemic.
As an epidemiologist, to determine which pools in the park are contaminated, I need to note down the data for each sick child and find out the pools visited by each person. The data would then be divided into the different age groups for better comparison.
The fact that no older children or adults developed the disease shows that the children had weak immune systems due to less age. People having extremes of age like very old people and very young kids have a weak immune system, which is not properly developed.
The park operators could frequently check the chlorine levels in all the pools to reduce the chances of future outbreaks of Shigella.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 5FB
- Diseases that are naturally spread from their usual animal hosts to humans are called zoonoses.
- Humans can acquire diseases like yellow fever, anthrax and rabies directly from animals. The animal usually acts as the reservoir. Sometimes, the animal is asymptomatic while sometimes the animal also suffers from the disease.
- Zoonoses can also constitute viral, bacterial, fungal, protozoan, and helminthic diseases.
- These microbes usually use animals as their reservoir host and get transferred to humans either through vectors or directly through animal bites.
- Fecal contamination can also lead to zoonoses. Fungal infections like ringworm need to have direct contact for transmission to humans. They are transmitted from domestic animals to humans.
- Viral infections like yellow fever are often spread by specific mosquitoes. The Hantavirus pulmonary syndrome is spread when the viruses in dried feces is inhaled. Worm infestations are usually through ingested larvae or eggs.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 5MC
Contamination is the presence of microbes on the surface of the object. Usually contamination objects do not cause infection but can become opportunistic pathogens. Contamination is not the process by which microorganisms attach to cells. Hence, the option (b) is incorrect.
The definition of disease is a condition in which the normal functioning of the body is hampered. Disease can be due to the infection by microorganisms, fungi or parasites. It is not the attachment of microorganisms to cells. Hence, the option (c) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 5SA
The five stages of infectious diseases in the correct sequence are:
- Incubation period
- Prodromal period
- Incubation period:
The period between infection by the microbe and the appearance of first symptoms is called the incubation period. It will vary depending on many factors like:
- Virulence of the microbe
- Infective dose
- Health of the person
- Reproductive time period of microbe
- Site of infection
- Prodromal period:
The period in which general symptoms are seen in the patient is known as prodromal period. The symptoms would be malaise, body aches, and weakness. This period is not seen in all illnesses.
The most severe stage of the disease with all specific symptoms is known as illness. The full effect of the microbes is seen in the body. If any toxins are produced, the effect is usually seen during this period. This is the stage when a patient usually visits the doctor.
In this period, the immune system of the patient slowly responds and begins to eliminate the microbes from the body. If any medical treatment is given, it also works to eliminate the microbes from the body. During this stage, the symptoms of the disease usually decrease. If the symptoms do not decrease, the disease is said to be fatal.
During this period, the body of the patient returns to normal. The damages done by the microbes are slowly restored or repaired. The convalescent period varies from disease to disease. The length of the convalescent period depends on the amount of damage done, the nature of the microbe, the immune system of the patient and the site of infection.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 6CT
Lichen is a combination of a fungus and an alga, which grow together in a relationship of symbiosis. Each member gains from the relationship. The photosynthetic partner of the lichen is the alga, which has photosynthetic pigments. These photosynthetic pigments help it to perform photosynthesis.
The fungal partner provides the shelter for the alga. It also helps in retaining water and serves as a larger absorption area. The fungus surrounds the algal cells completely and sometimes the fungus penetrates the algal cell wall. This is similar to the haustoria seen in pathogenic fungi.
The algal partner reduces atmospheric carbon dioxide to organic compounds, which serves as food for both the partners. The fungus provides water and minerals to the algal partner, in addition to protection.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 6FB
Transmission of microbes through fomites is called indirect contact transmission. Normal infections like common cold and worm infestations can be easily transmitted through fomites. When a person with cold touches a chair, automatically transfers bacteria to the chair. The next person who touches the chair is likely to be infected. Even medical equipment in hospitals like dental equipment can be a source of microbes. They can easily transfer to patients. The bed sheets in hospitals can also be a source of infection if not washed properly. In the same way, the operation apron of the surgeons should be sterile.
Needles and blood products are very easy way of transmission. When contaminated needles are used and blood products are not checked for diseases, dangerous diseases like AIDS and Hepatitis can be transmitted. In houses, worm infestations can spread easily if not kept in check. The person suffering from worm infestations should be careful to infect others through fomites.
Nonliving reservoirs of disease, such as toothbrush, drinking glass, and needle, are called fomites.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 6MC
The first stage of infection is incubation. This stage is not followed by the stage of decline. The stage of decline occurs after the stage of illness. The correct sequence of events for an infectious disease is incubation, prodromal period, illness, decline and convalescence. Hence, the option (b) is incorrect.
The first stage of prodromal period is incorrect. The first stage of an infectious disease is always incubation. In the order given in this option, the first two options are interchanged. Hence, this option (c) is incorrect.
The first stage of convalescence is incorrect. The first stage of an infectious disease is always incubation. Hence, the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 6SA
The three modes of disease transmission are:
- Contact transmission
- Vehicle transmission
- Vector transmission
- Contact transmission:
There are three types of contact transmission:
- Direct contact:
Direct contact involves touching and other activities between two persons. Sexual diseases are transmitted through sexual contact and skin diseases can be transmitted through hugging and other skin-to-skin contact. The transfer of microbes from mother to fetus through the placenta is another mode of direct transmission.
- Indirect contact:
Indirect contact occurs through fomites. Fomites are non-living objects, which has been contaminated by the patient. When a healthy person uses or touches the same object, the pathogens get transferred to the healthy person. Objects like needles and syringes can also be used in the transfer of microbes.
- Droplet transmission:
This type of transmission occurs through droplets. When a person sneezes, the droplets from the sneeze remain in the air for a long period of time. When a healthy person enters the same area and breathes that air, these pathogens then enter his body and cause disease. Only if the pathogens are transmitted for a distance of less than 1m, it is called droplet transmission.
- Direct contact:
- Vehicle transmission:
There are four types of vehicular transmission:
- Airborne transmission:
When pathogens from sneezing or coughing are transmitted over a distance of more than 1m, it is known as airborne transmission. If the distance is less than 1m, it comes under droplet transmission.
- Waterborne transmission:
Some diseases are transmitted through water. When fecal contamination occurs, waterborne diseases occur. Large water bodies can also act as a reservoir for pathogens.
- Foodborne transmission:
The transmission through foods is usually through undercooked or poorly refrigerated foods. Improperly pasteurized milk can also be a source of pathogens. Foods can also be contaminated with normal flora.
- Bodily fluid transmission:
Blood, urine, and saliva are the usual body fluids in the transmission of pathogens. Health workers can be easily affected by body fluids if they are not careful. Some diseases like AIDS (Acquired immuno deficiency syndrome) are transmitted through blood. So, if the health worker has a slight injury in a hand and handles blood, there is a high risk of getting infected.
- Airborne transmission:
- Vector transmission:
There are two types of vectors:
- Biological vectors:
In some diseases, the vector not only carries the pathogen, but also serves as a host for the pathogen. Sometimes, a part of the lifecycle of the pathogen occurs in the vector. The usual sites of replication within a vector are the salivary glands and the gut.
- Mechanical vectors:
These vectors only act as carriers. They do not act as hosts for the pathogens. The pathogens are usually carried on the feet or other body parts. A good example would be the housefly which carries pathogens from the dustbin to the kitchen.
- Biological vectors:
Microbiology with Diseases by Taxonomy Chapter 14 Answers 7CT
In the clinical case study of the Legionnaires’ disease, the facts are given below:
- 33 cases of the disease in the town
- Total population is 16,000
- It is a potentially fatal disease
- All victims had shopped at the same grocery store
- The vegetable misting machine was the source of the bacteria
The incidence of this Legionnaires’ disease can be calculated in the following way:
The incidence rate is 2.06 per 1000 people.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 7FB
There are three types of nosocomial infections:
The infections are acquired from outer environment. They can be due to working with infectious patients or handling their clothes. Even patients with low immunity levels can be infected with microbes in a hospital setting.
The endogenous infections are also called as nosocomial infections, but arise from the patient himself. Normal floras, which are present all over the body, can turn into pathogens when the immunity of the individual is lowered.
The infections are known as physician induced infections. The instruments used by the physician can serve as fomites. Even medical equipment in hospitals like dental equipment can be a source of microbes. They can easily be transferred to patients.
Thus, nosocomial infections are acquired by patients or staff in health care facilities.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 7MC
- The pathogens which are highly virulent are the most likely to cause disease in hosts. These pathogens easily pass the defenses of the body and cause infection. Since they are without any defective or absent enzymes, they are the most likely to cause disease. Hence, the correct option is (d) highly virulent organisms.
- The normal flora of the body can become opportunistic pathogens. The normal flora is usually present in almost all parts of the body and does no harm. But when the immunity of the host becomes low, this normal flora can cause disease. But, it does not always occur. Hence, the option (a) is incorrect.
- Those pathogens which lack the enzyme kinase cannot carry out many reactions of the cell. One example would be the process of signal transduction. This process needs the enzyme of kinase. Hence, it would be difficult for such pathogens to cause disease. Hence, the option (b) is incorrect.
- Those pathogens which lack the enzyme collagenase cannot carry out some important reactions of the cell. The enzyme collagenase is required to lyse the protein collagen in host cells. When this important enzyme is missing, it would be difficult for such pathogens to cause disease. Hence, the option (c) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 7SA
The parenteral route of infection can be described in the following way:
The parenteral route of infection is not a portal of entry. Microorganisms cannot easily enter the body through this route. Pathogens can use this route only with the help of instruments or any other human means.
The parenteral route is the one used to give injections. So when injections are given, there is a chance of pathogens gaining entrance into the body through the puncture site. The gashes by a nail are also enough for pathogens to enter the body.
Other methods include being pricked by a thorn, cuts, bites, stab wounds, surgical wounds, and deep abrasions. All these are the means by which pathogens can use the parenteral route. In the absence of any of these methods, pathogens cannot enter the body through the parenteral route.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 8FB
The total number of cases of a disease in a given area is its prevalence.
- The prevalence of a disease is tracked by epidemiologists. Prevalence is the total number of cases of that specific disease. The total number includes the new cases and the existing cases in a given area in a specific period of time.
- Prevalence is usually stated as a percentage. It is given as the number of affected people out of the total population. It can also be given as number of cases per 10,000 or per 100,000 individuals.
- Prevalence differs from incidence in that prevalence is the number of existing cases and the number of new cases, while incidence is the number of new cases. Prevalence is used to compare statistics over a long period of time.
- The statistics taken 2 years ago can be compared with the statistics taken 5 years ago. This type of comparison helps us to know whether the disease regularly appears in a specific period or if it reduces over a long period of time. Hence, the correct answer is prevalence.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 8MC
The capsule enhances the virulence of a bacterium. Since the capsule helps the cell in attachment to host cells and also in evading the defense systems of the host, it helps to increase the virulence of the bacterial cell. The cilia and the mucous secretions in the respiratory tract of the host are easily bypassed when the bacterium possesses a capsule. Hence, the correct option is (c) affects the virulence of these bacteria.
The capsules present in bacteria do not cause clotting. They usually play a role in the virulence of bacteria. They help the bacterium in evading the defense mechanisms of the host. The nature of the capsules might be different in different bacteria. Hence, the option (a) is incorrect.
A capsule helps the bacterium to evade the phagocytic cells of the host. It does not allow phagocytes to engulf the bacterium. Some bacteria like Pneumococcus have a capsule, which helps them to easily attack the respiratory system of the host. Hence, the option (b) is incorrect.
The capsule of a bacterium does have a specific effect on the virulence of the bacterium. The presence of a capsule on the outer side of a bacterium helps it to evade the phagocytes of the immune system of the host. Thus, when encapsulated bacteria lose their capsules, they become avirulent. Hence, the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 8SA
Transient microbiota can be compared with resident microbiota in the following way:
Microbiota can consist of bacteria, fungi, and protozoa. These normal microbiota are usually acquired from the hospital environment and surrounding people after the birth of the child.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 9FB
An animal that carries a pathogen and also serves as host for the pathogen is a biological vector.
These vectors also serve as hosts for the pathogen they carry. The pathogen usually carries out a part of its lifecycle in the body of the vector. The example is malarial pathogen. The Anopheles mosquito also serves as a host and a part of the lifecycle is carried out in the mosquito.
Biological vectors are usually bugs, flies, mites, fleas, lice, ticks, mosquitoes, and blood-sucking arthropods. The usual site of replication within a vector is the salivary gland or the gut. The bite of the vector usually carries the pathogen, which is directly injected into the next host.
Biological vectors are different from mechanical vectors. When transmission occurs through mechanical vectors, the lifecycle of the pathogen does not occur in the vector. The vector simply carries the pathogen on their feet or wings. Hence, the correct answer is biological vector.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 9MC
Some bacterial cells can produce endotoxin when they die. These endotoxins are responsible for the adverse affects seen in the host. The endotoxins are not produced when the bacteria lose their ability to make adhesins. Adhesins are proteins required for the attachment of the bacterial cells to host cells and endotoxins are released when the bacterium dies. Hence, the option (b) is incorrect.
When bacterial cells are unable to produce adhesins, they do not absorb endotoxins. Endotoxins are the products released by bacterial cells when they die. These endotoxins are usually present in the cell wall of Gram negative bacteria. When bacterial cells are unable to produce adhesins, they become avirulent. Hence, the option (c) is incorrect.
When bacterial cells are unable to produce adhesins, their virulence is not increased. Instead of virulence increasing, the virulence decreases. Since adhesins are useful in attachment of bacteria to host cells, when adhesins are not produced, the bacteria can no longer attack the host cells. This leads to loss of virulence. Hence, the option (d) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 9SA
The terms “infection” and “morbidity” can be compared in the following way:
An infection is the term used when a pathogen successfully crosses all the barriers and defenses of the immune system and multiplies in the body. The multiplication of the pathogen may not cause any visible symptoms in the body. The infection might not lead to disease or appearance of any strange symptoms. The normal functioning of the body is also not affected.
The term morbidity is used differently when compared to infection. As in infection, a pathogen needs to cross the barriers of the immune system and establish itself in the body. It also multiplies in the body of the host. But, in this case it causes the appearance of symptoms in the host. The appearance of the specific symptoms leads to disease. In morbidity, the normal functioning of the body is affected and health is lost.
The terms infection and morbidity only differ slightly in that the presence of infection does not always indicate a disease; while in morbidity, the symptoms and presence of disease is seen.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 10FB
Endotoxin is the part of the cell wall known as lipid A in a Gram negative bacterium.
The endotoxin is the lipid part present in Gram negative bacteria. These endotoxins are released only under certain conditions. When the cell dies or divides or is digested by phagocytes, lipid A is released. There are different types of lipid A, which are present in different bacterial cells.
The symptoms of endotoxin poisoning are:
- Blood coagulation
- Hemorrhaging, and
The different types of diseases which are due to endotoxins are:
- Typhoid fever
- Endotoxic shock
- Urinary tract infections
- Meningococcal meningitis
Hence, the correct answer is lipid A.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 10MC
An acute disease is a disease in which the symptoms develop rapidly. The severity of the disease becomes very high quickly but the decline is also quite fast. The duration of the disease is short. In this disease, the pathogen does not remain inactive. Hence, the option (b) is incorrect.
A chronic disease is a disease in which the symptoms develop slowly. The severity of the disease slowly increases and the decline of the disease is also quite slow. The duration of the disease is quite long. In this disease, the pathogen does not remain inactive. Hence, the option (c) is incorrect.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 10SA
Iatrogenic and nosocomial diseases can be compared in the following way:
Iatrogenic diseases are a part of nosocomial diseases. Iatrogenic diseases are also known as physician-induced diseases. When a physician uses improperly sterilized instruments, the microbes present on the instrument are easily transferred to the patient. These diseases can also be due to medical procedures done inside the body with the help of instruments.
Nosocomial diseases are diseases, which are acquired in a hospital setting. These diseases are usually acquired by health workers who work in hospitals and health facilities. The environment of the hospital and contagious patients usually give nosocomial diseases. The three types of nosocomial diseases are endogenous, exogenous, and iatrogenic infections. Endogenous infections are those, which are due to the normal flora becoming opportunistic pathogens. Exogenous infections are those acquired from the environment of the health facility. Iatrogenic infections are those, which are physician induced and arise due to instruments or medical treatments.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 11MC
The best definition of a pandemic disease would be the statement:
“It is an epidemic that occurs on more than one continent at the same time.”
a) It normally occurs in a given geographic area:
A pandemic does not occur in a given geographic area. When a disease occurs in a given geographic area, it is called an endemic but not a pandemic. Hence, this option is incorrect.
b) It is a disease that occurs more frequently than usual for a geographical area or a group of people:
A pandemic is not a disease that occurs more frequently than usual in a specific group of people. When a disease occurs in such a way that the frequency of the disease is more than usual and only occurs in a specific group of people, it is called an epidemic but not a pandemic. Hence, this option is incorrect.
c) It occurs infrequently at no predictable time scattered over a large area or population:
A pandemic is not a disease that occurs infrequently over a large population. When a disease occurs at no predictable time and infrequently over a large area, it is called a sporadic disease but not a pandemic. Hence, this option is incorrect.
d) It is an epidemic that occurs on more than one continent at the same time:
A pandemic is an epidemic that occurs on more than one continent at the same time. When the same disease is seen in large numbers over many continents, it is called a pandemic. Hence, this option is correct. Hence, the correct option is (d) it is an epidemic that occurs on more than one continent at the same time.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 12MC
Out of the following given types of epidemiologists, the one who is like a detective is an analytical epidemiologist.
a) A descriptive epidemiologist:
A descriptive epidemiologist needs to carefully tabulate and note down the data in connection with a disease. The area of spread of disease along with the information of the patients is tabulated. The transmission of the disease is also noted. Since these epidemiologists need to just tabulate and compare cases, they cannot be like a detective. Hence, this option is incorrect.
b) An analytical epidemiologist:
An analytical epidemiologist is a person who investigates a disease. He also analyzes the cause, the mode of transmission and the prevention of the disease. Such a person analyses these details only after the outbreak has occurred. He also has to find out if there are any other factors like age and sex which influence the spread of the disease. Since, an analytical epidemiologist needs to analyze and investigate just like a detective, this option is correct.
c) An experimental epidemiologist:
An experimental epidemiologist usually uses a hypothesis to test the cause of a disease. These epidemiologists also involve studies and experiments to test out the hypothesis. They can experiment on humans or animals. These people need to test and check whether a specific drug can be used to treat the disease. They also need to test for the cause and prevention of the disease. Since, an experimental epidemiologist does not analyze but only experiments, he is not like a detective. Hence, this option is incorrect.
d) A reservoir epidemiologist:
A reservoir epidemiologist usually checks out for the reservoir host of the pathogen causing the disease. A pathogen usually multiplies in a reservoir host without causing any symptoms in the host. The pathogen is then transmitted either to the intermediate host or to the final host. Since, a reservoir epidemiologist does not need to analyze, he is not like a detective. Hence, this option is incorrect. Hence, the correct option is (b) an analytical epidemiologist.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 13MC
The details of a case are given below:
A virus has infected an animal. A mosquito bites the animal and gets contaminated by the virus. The mosquito then goes and bites a human being. The vector in this case is the mosquito.
The animal cannot be the vector in this case. A vector is one which transfers the virus from one host to another. In the above case, the animal does not transfer the virus from one host to another. It is acting as the reservoir host in this case. Hence, this option is incorrect.
The virus cannot be the vector in this case. The virus is the pathogen in this case. A vector is one which transfers the pathogen from one host to another. Since it is the virus which is getting transferred and not the one which transfers, it cannot be the vector. Hence, this option is incorrect.
The mosquito is the vector in this case. It transfers the virus from the animal to the human being. In this case, the animal is the reservoir host while the human is the final host. The mosquito transfers the pathogen from the reservoir to the host. Hence, this option is correct.
The person cannot be the vector in this case. Since the person is the final host in this case, it cannot be the vector. Also, the human does not transfer the virus to any other human or organism. The human is at the receiving end of the chain and does not transfer the virus. Hence, this option is incorrect. Hence, the correct option is (c) mosquito.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 14MC
The details of the case are given below:
A patient contracted the disease of athlete’s foot after using a specific medicine for a long time. His doctor explained that the disease was directly due to the medication. Such diseases or infections are called as endogenous infections.
a) Nosocomial infections:
These infections are not due to long term use of medicines. When a health worker works in a hospital or health facility, he can acquire the infection from the hospital. He can acquire it from a patient or through fomites or through aerosols. Hence, this option is incorrect.
b) Exogenous infections:
These infections do not occur due to long term use of medicines. These infections are acquired from the environment of the hospital. These are usually acquired by hospital workers and helpers. These are one type of nosocomial infections. Hence, this option is incorrect.
c) Iatrogenic infections:
These infections are also called as physician induced infections. They can occur when doctors use improperly sterilized instruments or through catheters or any surgical equipment. These infections are usually acquired during surgery or any cleaning procedures in hospitals. They are not caused due to long term use of medicines. Hence, this option is incorrect.
d) Endogenous infections:
These infections are those which occur when the immunity of the person becomes low. Since the whole body is covered with normal flora, when immunity is lowered, these normal flora cause disease. In the above case, the long term use of medicine lowered the immunity of the person. The lowered immunity gave the normal flora the opportunity to become pathogens. Hence, this option is correct.
Hence, the correct option is (d) endogenous infections.
Microbiology with Diseases by Taxonomy Chapter 14 Answers 15MC
Out of the following given phrases, the best one which describes a contagious disease is “a disease that is easily passed from host to host in aerosols.”
a) A disease arising from fomites:
Fomites are non-living objects which can play a part in transfer of microbes. A good example would be the presence of cold-causing bacteria on the hands of the patient. When he holds a chair, he transfers these bacteria to the chair. When a normal person holds the same chair, he gets infected by these bacteria. In this way, the chair acts as a fomite in the transfer of microbes. Hence, this option is incorrect.
b) A disease that is easily passed from host to host in aerosols:
A disease which is passed through aerosols is called a contagious disease. A contagious disease can easily spread from one person to another. Some examples of contagious diseases are common cold and tuberculosis. Both these diseases spread through aerosols. When a person sneezes, the droplets from the sneeze remain in the air and can enter the respiratory tract of the next person who comes to that place. Hence, this option is correct.
c) A disease that arises from opportunistic, normal microbiota:
A disease that arises from normal microbiota is called an endogenous infection. Normal flora are the microbes which are present permanently on our body. These flora usually do not harm the body. But, when the immunity of the person becomes low, sometimes these normal flora becomes opportunistic pathogens. They cause disease. These diseases cannot be passed from one host to another through aerosols. Hence, this option is incorrect.
d) Both a and b:
The option of (a) is not correct. A disease arising from fomites is not contagious through aerosols. It is contagious but through fomites or non-living objects. The option of (b) is correct. But both these options cannot be correct. Hence, this option is incorrect. Hence, the correct option is (b) a disease that is easily passed from host to host through aerosols.