Microbiology with Diseases by Taxonomy Chapter 25 Answers
Microbiology with Diseases by Taxonomy Chapter 25 Answers 1CM
Polioviruses belong to the genus Enterovirus. These enterovimses are transmitted by fecal-oral route.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 1CT
RSA(ribonucleic acid) viruses are grouped into 15 families. Moreover, positive single stranded RNA viruses are classified into eight families and negative single stranded RNA viruses are classified into six families. Among them only one family is having double stranded RNA viruses.
The dichotomous keys for 15 families of RNA viruses are listed below:
Microbiology with Diseases by Taxonomy Chapter 25 Answers 1L
The steps in retroviral replication in HIV are as follows:
- The HIV (human immune virus) attaches itself to the cell and penetrates.
- It is uncoating itself.
- Synthesis of dsDNA takes place and the virus enters the nucleus.
- Latency – The virus may remain dormant for years or can be activated soon.
- Synthesis – Viral particles are synthesized
- Assembly and budding – Two RNA molecules make a new virion with the enzymes reverse transcriptase, and integrase and two tRNA molecules. The virions bud from the cytoplasmic membrane.
- Maturation of the virion – Protease releases reverse transcriptase and capsomeres. This makes the HIV virulent.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 1M
- The term myocarditis matches with the term (K) Picornaviridae. Encephlomyocarditis virus belonging to cardiovirus genus causes encephalomyocarditis in pigs. Piglets which get this infection show encephalitis and myocarditis and die suddenly.
- The term Colarado tick fever matches with the term (C) Reoviridae. This disease is caused by coltivirus of family Reoviridae. This virus is an arbovirus causing a zoonosis called Colarado tick fever. This disease is transmitted by ticks.
The term Rabies matches with the term (A) Rhabdoviridae. Rabies virus belongs to the family Rhabdoviridae. This disease is a zoonosis of mammals. The animal reservoir is dog in urban areas. Foxes, bats, and cats also are reservoirs of this virus in the wild areas.
- The term influenza matches with the term (G) Orthomyxoviridae. This disease is caused by two species of family Orthomyxoviridae. It has host such as vertebrates, pigs, birds and horses, and mammals. Vertebrates include humans also. Air-borne viruses spread the infection and also through fomites.
- The term Dengue fever matches with the term (F) Flaviviridae. A virus belonging to the family Flaviviridae causes dengue fever. This is transmitted by Aedes mosquito. This is also called breakbone fever because of the severity of the pain.
The term German measles matches with the term (D) Coronoviridae. This disease is caused by Rubella virus. It is a childhood disease and cause rashes. As the German scientist found out that it is a separate disease, this is named as German measles. It is infectious only to humans.
- The term acute gastroenteritis matches with the term (I) Calciviridae. Calciviruses cause acute gastroenteritis. They infect humans through digestive route and cause this disease. It causes outbreak of gastroenteritis in schools and day care centers.
- term Ebola virus matches with the term (J) Filoviridae. Ebola virus belongs to the family filoviridae and cause haemorrhagic fever. The predominant feature of this infection is that it causes bleeding under the skin and also through every opening of the body. Almost 90% of the humans infected by Ebola virus die.
- The term RSV matches with the term (B) Paramyxoviridae. This is called Respiratory syncytial virus, which belongs to the genus Pneumovirus and family Paramyxoviridae. It causes lower respiratory infection in young children. It affects the lung and form syncytia. Also dead cells, fibrin and mucus plug block the small air passages causing difficulty in breathing.
The term Western equine encephalitis (WEE) matches with the term (E) Togaviridae. Togavirus cause this disease. The normal host for this virus is bird.
- The term ‘No known disease’ matches with the term (H) Orphan virus. The term orphan virus applies to the virus that is not associated with any known disease. The viruses of the family Reoviridae causes diseases of respiratory tract and gastrointestinal system. Previously this fact was not known. Hence, it was called orphan virus with no known disease.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 1MC
- A segmented genome is one that has more than one strand of nucleic acid. Hence, (a) is the correct option. Negative, enveloped, ssRNA (single stranded RNA) viruses have a segmented genome. The genome in the virus is fragmented into two or more nucleic acid molecules and is packaged into different RNA (ribonucleic acid) segments. Examples of such viruses are flu virus of family Orthomyxaviridae and many viruses in Bunyaviridae and Arenaviridae. They usually infect animals also they can be transmitted to humans.
- Option (b) is not correct because a segmented genome do not have double-stranded RNA. But they have more than one strand of nucleic acid. Negative sense ssRNA viruses have segmented genome.
- Option (c) is not correct as a segmented genome does not have both RNA and DNA strands. The negative ssRNA viruses, which belong to the family of Orthomyxoviridae, Bunyaviridae, and Arenaviridae have segmented genome.
- Option (d) is not correct as a segmented genome does not have +ssRNA and -ssRNA molecules. A segmented genome is present in -ssRNA. Orthomyxoviridae and Bunyaviridae are examples of negative sense ssRNA, which have segmented genome. Hence, the correct option is (a) has more than one strand of nucleic acid.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 1SA
Life cycle of the arboviruses is between a host and a vector. Common vectors are mosquitoes, ticks, sand flies, and other blood sucking arthropods.
During the blood meal, the viruses are injected into the human body by the vectors. Inside the human body the viruses undergo amplification. Due to replication of virus at sufficient levels, viremia is caused. In this condition, there is huge number of viruses in the human blood circulation. Thus, the uninfected vector can ingest the virus during a blood meal and can transmit the virus to an uninfected human.
If viremia is not achieved in the human host, the transmission of the virus to the vector is not possible. This is the dead-end of the virus in the human host.
Humans are considered as dead-end hosts to many arboviruses, as persistent viremia does not occur in humans. They enter the target cells and replicate inside the cells. So, within 3-7 days of infection, mild flu like symptoms appears. This is the initial manifestation and arboviruses cannot go beyond this level.
In some cases, arbovirus in the blood may affect brain, liver, and skin. This is second –stage infection. This may result in encephalitis, yellow fever, and dengue fever.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 1TF
This statement- A single virion is sufficient to cause cold is a true statement.
Even though many viruses cause cold, more than 100 types of viruses of genus Rhinovirus (rhinoviruses) causes cold.
Rhinoviruses are limited to upper respiratory tract. They are very infective. Entry of a single virion is sufficient to cause cold in more than 50% of the exposed individuals.
When the infection is severe, more than 100,000 virons are present in each millimeter of mucus membrane in the nasal cavity. An infected individual spreads the infection by releasing the viruses into the surroundings. From the surroundings it is transmitted by aerosols or through hand contact. Infection occurs through inoculation by hand into the into the mucus membrane of the eye. From the eyes it is washed into the nasal cavity by tears.
So, a single virion is sufficient to cause cold. This statement is TRUE.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 2CT
A 20 year old man is bought to emergency room. He was suffering from seizures, disorientation, hallucinations, and an inordinate fear of water. His family member has reported that he is having a history of headache and fever. Moreover, he was bit by a dog before his admission in hospital.
Diagnosis: The reports of the patient have revealed that he is suffering from rabies.
Treatment: Vaccination at this stage will not be an effective treatment.
Animal reservoirs: Raccoons are source of rabies virus in South Carolina.
Additionally, relatives of the patient who had direct contact with the patient are advised to receive prophylactic treatment. Since, the saliva of the patient has rabies virus and are infective they are prone to get infection.
Thus, the treatment involves rabies vaccine (human diploid cell vaccine) and human rabies immunoglobulin.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 2MC
- In families Picornaviridae, Caliciviridae, Astroviridae, Coronaviridae, Togoviridae, Flaviviridae, and Retroviridae common feature is that they all have positive single-stranded RNA genomes. They are based on RNA (ribonucleic acid) polymerase. Hence, the option (c) is correct.
- Option (a) is not correct because all of them are not arboviruses. Arboviruses are the viruses, which are transmitted by arthropod vectors. The genus Alphavirus belonging to family Togaviridae comes under Grorp A arbovirus. Genus Flavivirus belonging to family Flaviviridae comes under Group B arbovirus. Family Picornaviridae also comes under arbovirus.
- Option (b) is not correct because they are pathogenic viruses. A picornavirus causes common cold, poliomyelitis, and so on. Calicivirus causes acute gastroenteritis. Astroviridae causes diarrhea, vomiting, and fever. Corona viruses cause Severe Acute Respiratory Syndrome. Toga viruses cause chikungunya. Flaviviridae causes yellow fever and dengue fever. Retroviruses cause tumors. Hence, all these families are pathogenic viruses.
- Option (d) is not correct because they are not negative single stranded RNA genomes. All the above mentioned families have positive single stranded RNA genomes.
- Hence, the correct option is (c) they have positive single-stranded RNA genomes.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 2SA
Five classical childhood diseases that produce rashes or skin lesions are as follows:
- Fifth’s disease
Fifth disease or erythema infectiosum is caused by erythrovirus, which is also called parvovirus B19. It starts with low-grade fever, and cold symptoms. After few days, bright red rash appear on the face.
Chickenpox is caused by varicella Zoster virus. This is a very contagious disease. The early symptoms are low grade fever, and body aches. The disease starts with rashes which start as macules first and then papules and then vesicles. The lesions appear mainly on the body and head and spread to face and limbs. In severe cases, rashes can spread to oral mucous membrane, pharynx, and vagina.
Rubella is caused by rubella virus. Other name for this disease is German measles after the German physicians, who first described this disease. This is a mild form of disease. Rashes appear on the face and then to the trunk and limbs. Within 3 days the rashes disappear. There is mild fever, swollen lymph glands, joint pains and conjunctivitis.
Rubeola is otherwise called measles or red measles. It is a serious childhood disease and more contagious disease. It is caused by a paramyxovirus belonging to genus Morbillovirus. There will be fever for 4 days and cold, coryza and redness of eye are present. The diagnostic sign of measles is koplik’s spots. In many cases, it is not seen because they may disappear in a day.
Roseola is also called roseola infantum. It is caused by Roseola virus. Human herpesvirus-6 and human herpesvirus -7 are collectively called Roseolavirus. It generally affects the children below 2 years of age. It occurs in children between six months to two years of age. Sometimes there may be manifestation of high fever few days before the appearance of rashes.
If a child develops some rashes or skin lesions the question that can be asked to determine the type of virus are as follows.
- What is the age of the child?
- Whether the child had fever before the onset of skin lesions?
- Does the child have cold like symptoms?
- Are there any rashes in the mucous membranes?
- Is the child tired and exhausted?
Microbiology with Diseases by Taxonomy Chapter 25 Answers 2TF
This statement- All infections of polio are crippling is not a true statement.
There are four conditions in the infection of poliovirus. They are asymptomatic infections, minor polio, non-paralytic polio, and paralytic polio.
The paralytic polio infection occurs less than 2% of polio infections. In this paralytic polio, the spinal cord and motor cortex are invaded by the virus. Hence, the nerve impulse conduction is limited.
The degree of paralysis depends upon the type of polio virus involved and also the infective dose. The degree of paralysis depends on the health and age of the infected person.
In a condition called bulbar poliomyelitis, the medulla and the brain stem are affected. This results in paralysis of muscles in limbs or respiratory muscles, for which iron lungs were once used.
In some cases of paralysis, the paralysis is lifelong and the person would not be recovered, while in some cases, full recovery occurs after 6 months to 2 years. Hence, the given statement is FALSE.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 3CT
Derivation of the name coltivirus:
Coltivirus is the causative organism of Colorado tick fever. The word colti is derived from (Col) orado (ti) ck virus – col+ti = coltivirus. Hence, coltivirus got its name from Coloradotick virus. Moreover, coltivirus belongs to family Reoviridae. It is carried by rodents and is transmitted to humans through tick bites. However, the disease is endemic in Rocky Mountains, Colorado.
Thus, the clinical manifestations of this disease are ocular pain, myalgia, biphasic fever, and photophobia.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 3MC
- The smallest animal viruses are in the family Picornaviridae. The name itself shows that pico means small. So these viruses are small RNA viruses. They are naked, +ssRNA (positive sense single stranded RNA) viruses with an icosahedral capsid. The size of the viral particle is nearly 27-30 nm. The genome is almost 2500 nm in length but it is packed so tightly. This family is separated into many genera, which have pathogens of animals and humans. Hence, the correct option is (d).
- The option (a) is not correct because the family Caliciviridae does not have smallest animal viruses. They are non-enveloped single stranded RNA viruses and non-segmented. The length of the viruses is 7.5-8.5 kb. The capsid is 27-40 nm.
- The option (b) is not correct because the family Astroviridae viruses are not smallest of animal viruses. They are isolated from mammals and avian species like ducks and chickens. They are 28-35 nm in length and they are icosahedral in shape. They are non-enveloped.
- The option (c) is not correct because the family Togaviridae does not have smallest animal viruses. They are enveloped and form spherical shapes measuring 65-70 nm in diameter. It has +ssRNA strand which is 10,000-12,000 nucleotides long. Hence, the correct option is (d) Picornaviridae.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 3SA
The five kinds of hepatitis mentioned in the chapter 25 are
- Hepatitis A
- Hepatitis C
- Hepatitis D
- Hepatitis E
- Yellow fever
Microbiology with Diseases by Taxonomy Chapter 25 Answers 3TF
This statement – Postpolio syndrome is due to latent polioviruses that become active 30-40 years after the initial infection is not true.
Postpolio syndrome is a crippling deterioration in the muscle function, which was affected by polio and extreme fatigue.
Postpolio syndrome is not by reemergence of poliovirus. It is not an infectious disease or phase, as the patient does not have the virus at this time.
Almost 80% of the people who had recovered from paralytic polio before 30-40 years develop this syndrome.
The cause for this syndrome is the age-related aggravation of nerve damage that occurred at the time of original infection.
So, this syndrome is not due to the latent poliovirus, but due to the aggravation of the nerve damage and it is age-related. There is no poliovirus active during the syndrome. Hence, the given statement is FALSE.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 4CT
Primer is necessary in DNA synthesis of Retroviruses, such as HIV:
The primer is essential to convert single stranded RNA (ribonucleic acid) into double stranded complimentary DNA (cDNA). Moreover, double strand cDNA can integrate into host genome by creating an infection that last long and cannot be eradicated. This process is mediated by reverse transcription, catalyzed by an enzyme reverse transcriptase. However, the process occurring in replication of HIV virus of retrovirus can be explained in 3 steps.
- The RNA-DNA hybrid formed as +RNA genome uses tRNA that is carried by virus as primer for DNA synthesis.
- The RNA portion of the hybrid is degraded by the enzyme reverse transcriptase and the DNA is left.
- The enzyme transcribes complimentary DNA strand and dsDNA is formed. Thus, RNA primer is removed. Thus, primer is necessary in DNA synthesis of Retroviruses.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 4MC
- Rhinoviruses cause more colds. The viruses infect microvilli present in nasal cells crossing the layer of mucus. More than 100 types of viruses of family Picornoviridae in the genus Rhinovirus, cause colds. Hence, the correct option is (a).
- Parainfluenza viruses cause respiratory infection in children less than 5 years of age. Human pareinfluenza viruses -1, 2, and 3, cause lower respiratory tract infections. HPIV-4 causes mild upper respiratory infection. A condition called Croup is caused by HPIV-1 and 2 in which there is ‘seal bark’ cough, inflammation of larynx, trachea, and bronchi are seen. Hence, the option (b) is not correct.
- The viruses which belong to subfamily Pneumovirinae are called pneumoviruses. They cause acute respiratory infections. The pneumovirus genus has two members namely, the respiratory syncytial viruses, which affect humans and cattle. The second infects the rodents. Hence, the option (c) is not correct.
- The bunyaviruses do not cause cold. Many of the bunyaviruses are arboviruses. Humans are infected by the arthropods bites. They cause California encephalitis, hemorrhagic fever, and Rift valley fever. Hantaviruses are one type of bunyaviruses. It causes Hantavirus pulmonary syndrome, which is often fatal. Hence, the option (d) is not correct. Hence, the correct option is (a) rhinoviruses.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 4SA
The Human Immuno Deficiency virus or the AIDS virus destroys the immune system of the body. It causes acquired immunodeficiency syndrome. This is not a disease but a complex of diseases with complex signs and symptoms, with a common cause. Hence, it is called a “syndrome” instead of “disease.”
The resistance of the body gets lowered due to the death of helper T-cells of immune system. So, the body cannot fight against any infections, which results in variety of symptoms and variety of diseases. In this condition even minor illness can be aggravated into serious illness.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 4TF
The statement – as the oral polio vaccine contains line attenuated viruses, mutations of these viruses can cause polio – is true.
The oral polio vaccine was produced by using attenuated virus. The major drawback in the oral polio vaccine is that, it has the ability to revert to a form that can cause neurological infection and result in paralysis.
The disease caused by VDPV (vaccine-derived poliovirus) cannot be differentiated from the disease caused by wild virus. Even though it is a rare occurrence, some cases have been reported. This occurs in places where there is low coverage of oral polio vaccination.
Because of the iatrogenic effect of oral polio vaccine, nations turn from the oral polio vaccine to the injected vaccine. Hence, the given statement is TRUE.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 5CT
The alligator hide is very thick that mosquitoes cannot inject the West Nile virus into it. But, as the virus is an arbovirus, infects the migratory birds through mosquitoes. Moreover, birds in turn get infection and animals, which consume infected dead birds, get infected. This may be the case of alligators.
Therefore, the alligators that feed the infected birds are prone to get infection.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 5MC
- Arboviruses are viruses, which are transmitted to humans by arthropods. The onset of symptoms takes 3-15 days after exposure to the virus. The life cycle of these viruses is between the host and the vector. Common vectors are sandflies, mosquitoes, and ticks. Most togaviruses and flaviviruses are arboviruses. There is no taxonomic significance to the term arbovirus. The arboviruses may be +ssRNA, -ssRNA, and dsRNA. Hence, (c) is the correct choice.
- The zoonotic pathogens are not arboviruses. They are viruses, which cause diseases in animals that spread to humans. They are transmitted between the animals and humans sometimes by vectors. The arthropod vectors get infect with the arboviruses and infect the humans. But, in humans persistent viremia does not occur readily. So, humans become the dead end of zoonotic viruses. Hence, the option (a) is not correct.
- Arboviruses are not deactivated viruses used for vaccines. Viruses are grown in culture and then killed using chemicals like formaldehyde or heat. In this method the virus cannot multiply, but it can be recognized by the immune system as its capsid proteins are intact. So, response is evoked. So these deactivated viruses are used in vaccines. Hence, the option (b) is not correct.
- Arboviruses are not found in arbors. These are viruses, which are transmitted by arthropods. Hence, the option (d) is not correct.
- Hence, the correct option is (c) Viruses that are transmitted to humans via the bite of an arthropod.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 5SA
Influenza had been a deadly killer disease caused by flu virus. This pandemic disease can cause death in millions. Global deaths are 500,000 annually. This virus causes the death of epithelial cells and the lungs are exposed to bacterial infections. Many dead cells in the lungs cause death.
Flavivirus causes Yellow fever. This results in the degeneration of heart, liver and kidneys. Also intestinal hemorrhage occurs. The mortality rate is more than 20%. Yellow fever epidemics ravaged in America, Spain and West Africa. Globally there are about 30,000 deaths annually due to yellow fever.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 5TF
The statement – A typical host for a togavirus is a horse is a true statement.
Different types of togaviruses cause different diseases. Venezuelan equine encephalitis (VEE) is caused by this virus. The replication of the virus occurs in the brain of the horses and humans.
The vectors are Aedes and Culex mosquito. Natural hosts of this virus are rodents and horses.
This virus affects all the equine species like horses, zebras, and donkeys. After being infected by this virus the equines die suddenly.
The infected equines are the primary animal species that spread the virus. They develop large quantity of this virus in their blood circulation. When a mosquito bites the animal, the viruses are transmitted. Hence, the given statement is TRUE.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 6MC
- Negri bodies are associated with rabies. They are seen in the cytoplasm of nerve cells infected with rabies virus. They contain ribonuclear protein of the rabies virus. Postmortem laboratory tests are done to determine the presence of rabies virus in suspected animals. One such test is identification of negri bodies in the brain. Hence, the correct option is (d).
- Negri bodies are not associated with Marburg virus. These Marburg viruses cause viral hemorrhagic fever in humans and primates. Hence, the option (a) is not correct.
- Negri bodies are not associated with hanta virus. The hanta virus infects humans with rodent saliva, urine, or feces. Some types of hanta virus cause Hantavirus pulmonary syndrome and Hantavirus hemorrhagic fever with renal syndrome, which are fatal diseases in humans. Hence, the option (b) is not correct.
- Negri bodies are not associated with coltivirus. Coltivirus belongs to Reoviridae family. It causes Colorado tick fever. Hence, the option (c) is not correct. Hence, the correct option is (d) rabies virus.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 6SA
The given statement is incorrect.
Rubeola is called measles or red measles. It is one of the five classical diseases of childhood. Measles is caused by measles virus of the genus Morbillivirus of family Paramyxoviridae.
It is a highly contagious disease and serious childhood disease. It spreads by coughing, sneezing and also by personal contact.
The clinical manifestations are fever, sore throat, cough, conjunctivitis and headache. After two days Koplik’s spots appear on the mucous membrane of oral cavity. Red maculopapular skin lesions appear on the head and body. They fuse together to form huge rashes. This disease may result in death.
Rare complications are pneumonia and encephalitis. Most serious complication is subacute sclerosing panencephalitis (SSPE). This disease starts 1-10 years after the initial infection, lasts for few years and results in death. It has become much rarer disease due to vaccination in children.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 7MC
- Breakbone fever or Dengue fever will be affected if mosquitoes are eradicated from an area. This is caused by a flavivirus. This dengue virus is transmitted by mosquitoes belonging to several species of Aedes. The patient suffers with fever, pain in head, back, and muscles. The pain is so much that it is called breakbone fever. Once the mosquitoes are eradicated from an area, there will not be any mosquito vector to transmit the virus. Hence, the option (d) is correct.
- Mumps would not be affected if mosquitoes in one area are eradicated. Mumps is caused by mumps virus. They are transmitted by respiratory secretions. If an infected person coughs, the droplets enter the eyes, nose, or mouth of other person. By sharing water and food also it can spread. They survive on surfaces and can be transmitted by contact. So, mumps do not need mosquitoes for transmission. Hence, the option (a) is not correct.
- Measles would not be affected by the eradication of mosquitoes. Measles is caused by measles virus. It is transmitted by respiratory droplet infection. Different actions like coughing, talking, and sneezing spread the virus via droplets in the air. Hence, the option (b) is not correct.
- Hepatitis E is caused by hepatitis E virus. It is transmitted by fecal-oral route. It is fatal to pregnant women about 20%. This can be prevented by personal hygiene, good sanitation there by stopping the fecal-oral route transmission. Hence, the option (c) is not correct. Hence, the correct option is (d) break bone fever.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 7SA
The given label is B/Kuwait/6/10 (H1N3).
B denotes → type B influenza virus.
Kuwait → location Of original identification.
6/10 → Date Of original identification.
HIN3 denotes the strain of the virus → HA and NA antigens.
So, this label can be translated as influenza type B, in Kuwait, in June 2010, that contains HA and NA antigens of type I and type 3.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 8MC
- Koplik’s spots are oral lesions associated with measles. These spots are manifested in the mucous membrane of the mouth. They look like grains of salt surrounded by red halo. These spots are definite diagnosis of measles. Hence, the option (b) is correct.
- Koplik’s spots are not associated with mumps. In mumps, parotid salivary glands get enlarged and painful. Hence, the option (a) is not correct.
- Koplik’s spots are not associated with flu. Influenza is called flu. It is caused by RNA viruses called influenza virus. The common symptoms are fever, sore throat, muscle pain and chills. It is a severe disease but it can be confused with common cold. Hence, the option (c) is not correct.
- Koplik’s spots are not associated with colds. Cold is considered as common cold. It is infectious disease of the upper respiratory tract caused by viruses. The clinical manifestations are cough, sore throat, and fever. It affects the nose, throat, and sinuses primarily. Hence the option (d) is not correct.
Hence, the correct option is (b) Measles.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 8SA
Candidate viral diseases to be eliminated are
Measles – It affects specifically humans. It does not have any animal reservoir. It is a self-limiting disease and it is contagious only for a week. It has got effective vaccination. As it is so more contagious than smallpox and because of the repeated reintroduction of infection the country wide elimination does not have good outcome.
Rubella – It specifically affects human, with no animal reservoir and a good vaccination. It is a self-limiting disease. The eradication of Rubella needs intensive campaign. The difficulty of diagnosis is also a problem in eradicating this disease.
Hepatitis B – it is specifically human pathogen and has got a good vaccine. It is a disease of many persons. People, who get infected in infancy, are persistent and repeated source of this virus. So for eradicating this disease, all the countries should start it early.
HIV (Human immuno deficiency virus) or AIDS (Acquired immuno deficiency syndrome) virus once infects a cell, the genetic material is incorporated into that cell and it lasts for the life time of the cell. The currently available antiretroviral drugs do not destroy the virus and also do not remove the genetic material incorporated into the cell. As HIV shows latency, it gets reactivated anytime. Several years of antiviral therapy is not of much help because the latent HIV infection persists for longer years in some types of macrophages and CD4 cells. So, eradication of AIDS virus is still yet not possible.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 9MC
- Zoonoses are animal diseases that spread to humans. This may be parasitic, bacterial, fungal, or viral. The emergence of a pathogen into a new host is called emergence of diseases. Rabies and dengue fever are some examples of zoonoses. Hence, the option (a) is correct.
- are diseases specifically transmitted by mosquitoes and ticks. This option (b) is not correct. The zoonotic diseases can be transmitted by bats, cats, cattle, mice, pigs, and so on. There are so many zoonotic infectious organisms.
- Option (c) states that zoonoses agents are mucus borne viruses, which are transmitted in the droplets of moisture in a sneeze or cough. This is not correct option. These infectious agents that cause zoonoses are transmitted by vectors or by contact with the animals. It is may be droplet mucus borne rarely as in the case of rabies. The rabies virus in the saliva of infected animals is transmitted through a bite or through the cut or break in the skin, or through inhalation which is rare.
- Option (d) states that zooneses are diseases that can be transmitted from humans to an animal population. This is not correct option. In the case of anthroponosis, a disease causing agent, which is carried by humans are transmitted to other animals. Hence, the correct option is (a) they are animal diseases which spread to humans.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 9SA
The common tests for detection of viral diseases:
- Antibody test- to find the antibody specific to the viral infection. This test is done with the blood sample.
- Viral antigen detection test- this is to find the viral antigens develop on the surface of the infected cell. This test needs the tissue sample.
- Viral culture- viral culture may take weeks for growth.
- Viral DNA (deoxyribonucleic acid) or viral RNA (ribonucleic acid) detection test- it is to find the genetic material of the virus involved. The sample of tissue or spinal fluid or blood can be used for this test.
The most common tests dealt in chapter 25 are
- Serological test like ELISA (Enzyme linked immunosorbent assay) and agglutination of latex beads to which the arbovirus antigens are fixed. This is the test for arboviruses.
- For HIV (human immuno deficiency virus) infection, PCR –Polymerase chain reaction is done. Definite diagnosis can be done with this test. Serological tests like ELISA, agglutination, western blot testing is done that can reveal antibodies against HIV. The positive test for antibiotics just shows that the patient was exposed to HIV.
In the case of measles, serological tests confirm the measles antigen in blood and respiratory samples.
- For Respiratory syncytial virus, immunoassay is done. Respiratory fluids are tested for immunofluorescence, ELISA and complimentary DNA (deoxyribonucleic acid) probes are done.
- In the case of rabies, serological tests for antibodies would confirm the diagnosis.
- For influenza, ELISA test or immunofluorescence will differentiate the strains of the virus and confirm the diagnosis.
In bunyavirus infections ELISAs are used to detect and distinguish the viral antigens.
So, the most common tests are
- ELISAs (Enzyme linked immunosorbent assay)
- Polymerase chain reaction
Microbiology with Diseases by Taxonomy Chapter 25 Answers 10MC
- Ebola virus causes uncontrolled bleeding from the eyes, nose, mouth, ears, and anus. Ebola viruses belong to the family filovirdae. The initial method of transmission is not known. Fruit bats seem to be natural reservoirs of ebola viruses. The main clinical manifestation of this disease is internal bleeding under the skin and bleeding from all the openings of the body. The internal organs get reduced into a jelly-like substance. The reason behind the hemorrhage is the infected cells lining the blood vessels get affected by the virally coded glycoprotein. It prevents cells from adhering to one another and causes blood to leak out of the vessels. Almost 90% of the patients die. Hence, the option (a) is correct.
- Bunyavirus does not cause these symptoms. Most of these viruses are zoonotic pathogens. The four genera of the family bunyaviridae have human pathogens. Hemorrhagic fever, Rift valley fever, California encephalitis are some of the diseases produced by bunyaviruses. Each bunyavirus have their target. Some of the diseases are indistinguishable from diseases produced by other viruses. Hence lab tests are necessary for diagnosis. Hence, the option (b) is not correct.
- Hantavirus does not cause bleeding from eyes, nose, mouth, ears and anus. Humans get affected by Hantaviruses by contact with rodent excreta or saliva. Hantavirus hemorrhagic fever with renal syndrome (HFRS) and Hantavirus pulmonary syndrome (HPS) can be fatal. HFRS in later stages can cause vascular leakage. Hence, the option (c) is not correct.
- Human immunodeficiency virus does not cause bleeding. It is the progressive decline in the immune system allowing dangerous infections and cancers. It affects the helper T cells, macrophages and dendritic cells of immune system. Hence, the option (d) is not correct. Hence, the correct option is (a) Ebola virus.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 10SA
The West Nile virus is an arbovirus belonging to the family flaviviridae. It is endemic to Israel and Africa.
The virus is carried by the infected migratory birds across the lower states of US. Mosquitoes spread this viral infection among the birds, birds to horses; and birds to humans. This virus cannot produce significant viremia in humans and thus human is dead-end host for this virus.
In subtropical and temperate areas, the West Nile Encephalitis occurs in summer. In tropical areas the incidence of infection is greater in the rainy season due to the abundance of mosquitoes.
The West Nile virus became evident in US in summer 1999 in New York City. The epidemic occurred during extreme dry summers in urban SLE. The environmental conditions that are favorable for the amplification of this virus and transmission by hosts may be summer. That may be the cause that cases of West Nile Encephalitis is more in summer than in winter.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 11MC
- Reoviruses such as rotaviruses and coltiviruses are unique in having double-stranded RNA (ribonucleic acid). Reoviruses are the only microbes whether viral or cellular have double-stranded RNA in their genome. Every virus has 10-12 segments of double-stranded RNA. They are also called orphan viruses. They got the name reo as an acronym from ‘respiratory, enteric, orphan’. Hence, the option (b) is correct choice.
- Option (a) states that they are all naked, this is not correct. There are so many families who are naked without envelop. Families like Picornviridae, Calciviridae, Astroviridae, and Hepeviridae all of them are naked viruses. So, this is not the unique feature of reoviruses.
- Option (c) states that both the viruses are arboviruses and zoonotic. This option is not correct. Rotaviruses are transmitted by fecal-oral route. This is not an arbovirus. Coltivirus is an arbovirus and causes zoonosis called Colorado tick fever, as it is transmitted by tick bites.
- Option (d) states that both the viruses are having protein spikes. This option is not correct. Only rotavirus has spikes of glycoprotein on their capsids. They act as attachment molecule and thereby induce endocystosis. So, this is not the unique feature of both rotaviruses and coltiviruses. Hence, rotaviruses and coltiviruses are having double-stranded RNA, which is a unique feature. Hence, the correct option is (b) having double-stranded RNA.
Microbiology with Diseases by Taxonomy Chapter 25 Answers 11SA
- The 1918-1919 pandemic influenza viruses were the first one of the two influenza viruses. The second one of the influenza virus is A 2009 (H1N1). Both the types have many genetic sequences in common. The emergence of new strains like H1N1 viruses results in outbreaks internationally.
- 1918 pandemic killed young, healthy adults. It is called Spanish influenza. This virus kills through the over immune reactions of the body’s immune system. As the young people had strong immune system, thus kills the body. The weak individuals and children with weak immune system had fewer deaths.
- In Spanish influenza infection was only in the respiratory system. The cause of death was bacterial pneumonia and viral pneumonia. The genomic sequences of this virus were like an avian like H1N1virus. It did not have multibasic HA cleavage site, which shows that it is a highly pathogenic avian influenza virus.
- The 2009 H1N1 pandemic strain resulted from genetic reassortment of four influenza A viruses. The infection started in a Mexican town in February. In April, there were number of influenza like cases. There was human to human transmission. This made the WHO (World Health Organization) to elevate the pandemic alert.
- By May 21st, forty one countries reported cases of influenza. The genetic component of this 2009 H1N1 pandemic strain resulted from reassortment of H3N2 North American and H1N2 swine viruses. This was seen in pigs since 1997 and developed adaptation in pigs.