Virology 3 – 27 MCQs | Kenya MBChB

27 Year 3: Medical Virology exam questions on Virology 3 for medical students. Includes MCQs, answers, explanations and written questions. Sample: All of the fo

This MCQ set contains 27 questions on Virology 3 in the Year 3: Medical Virology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.

Q1: All of the following viruses are disseminated throughout the body EXCEPT ONE:

  1. A. HIV
  2. B. HBV
  3. C. Rabies virus
  4. D. Yellow fever virus
  5. E. Human papilloma virus

Correct answer: E – Human papilloma virus

HPV causes localized infections only and does not disseminate systemically via viremia. HIV, HBV, rabies virus, and yellow fever virus all cause systemic dissemination.

Q2: All of the following associations are true EXCEPT ONE:

  1. A. EBV can cause nasopharyngeal carcinoma
  2. B. CMV causes heterophil-negative mononucleosis
  3. C. Mumps virus can cause meningitis
  4. D. Poliovirus can cause paralytic disease
  5. E. Astrovirus causes gastroenteritis only in adults

Correct answer: E – Astrovirus causes gastroenteritis only in adults

Astrovirus primarily affects children, not adults. All other associations are correct.

Q3: Each of the following diseases is associated with infection by picornaviruses EXCEPT ONE:

  1. A. Myocarditis
  2. B. Hepatitis
  3. C. Meningitis
  4. D. Mononucleosis
  5. E. Herpangina

Correct answer: D – Mononucleosis

Mononucleosis is caused by EBV (herpesvirus), not picornaviruses. Coxsackieviruses cause myocarditis, HAV causes hepatitis, enteroviruses cause meningitis and herpangina.

Q4: All the following viruses belong to the Picornaviridae EXCEPT ONE:

  1. A. Coxsackievirus group A
  2. B. Rhinoviruses
  3. C. Poliovirus
  4. D. Rabies virus
  5. E. Echovirus

Correct answer: D – Rabies virus

Rabies virus belongs to the Rhabdoviridae family. Coxsackievirus, rhinoviruses, poliovirus, and echovirus are all members of the Picornaviridae family.

Q5: Which one of the following statements concerning mumps is CORRECT?

  1. A. The testes, ovaries and pancreas can be involved
  2. B. There is no vaccine against mumps
  3. C. Passive immunization is the only means of preventing the disease
  4. D. The diagnosis is made only on clinical grounds since the virus cannot be grown in cell culture
  5. E. Second episodes can occur since there are 2 serotypes

Correct answer: A – The testes, ovaries and pancreas can be involved

Mumps complications can include orchitis, oophoritis, and pancreatitis, in addition to the classic parotitis. There is an effective vaccine, and diagnosis can be made through laboratory methods. There is only one serotype.

Q6: Each of the following statements concerning HAV is correct EXCEPT ONE:

  1. A. The initial site of viral replication is the GIT
  2. B. The diagnosis is usually made by isolating the virus in cell culture
  3. C. HAV commonly causes asymptomatic infection in children
  4. D. Immunoglobulin is used to prevent the disease in exposed persons
  5. E. It is a member of the family picornaviridae

Correct answer: B – The diagnosis is usually made by isolating the virus in cell culture

Hepatitis A virus (HAV) is very difficult to culture. Diagnosis is typically made by detecting IgM anti-HAV antibodies using ELISA.

Q7: Acute hemorrhagic conjunctivitis is caused by which of the following viruses:

  1. A. Coronavirus
  2. B. Reovirus
  3. C. Rhinovirus
  4. D. Enterovirus
  5. E. RSV

Correct answer: D – Enterovirus

Enterovirus 70 and Coxsackievirus A24 are the primary causative agents of acute hemorrhagic conjunctivitis.

Q8: Which of the following statements about CNS viral infections is FALSE?

  1. A. Meningitis may occur together with encephalitis
  2. B. Enteroviruses are one of the commonest causes of CNS infections in childhood
  3. C. HSV encephalitis is a post-infectious encephalomyelitis
  4. D. Measles encephalitis is a post-infectious encephalomyelitis
  5. E. The detection of antibody in the CSF is a useful diagnostic marker

Correct answer: C – HSV encephalitis is a post-infectious encephalomyelitis

HSV encephalitis is a direct viral invasion of the brain, not a post-infectious encephalomyelitis. Measles encephalitis, on the other hand, is a post-infectious encephalomyelitis.

Q9: A 28-year-old female sex worker with HIV presents with headaches and CSF showing reduced glucose, elevated protein, 450 mononuclear cells/mL. Compatible with Cryptococcus, Coccidioides, or Candida meningitis. Which test is confirmatory for Candida?

  1. A. Positive CSF cryptococcal capsular antigen test
  2. B. Positive CSF complement fixation antibodies to coccidioidin
  3. C. Microscopic observation of oval yeast cells and pseudohyphae in CSF
  4. D. Positive skin test to coccidioidin

Correct answer: C – Microscopic observation of oval yeast cells and pseudohyphae in CSF

For Candida meningitis, microscopic observation of oval yeast cells and pseudohyphae in the CSF is confirmatory. Cryptococcus is confirmed by antigen tests, and Coccidioides by serology (complement fixation).

Q10: KOH examination of sputum from a heart transplant patient with fever and pulmonary infiltrates shows oval budding yeast cells and pseudohyphae. What is the diagnostic significance?

  1. A. Aspergillosis
  2. B. Candidiasis
  3. C. Hyalohyphomycosis
  4. D. Phaeohyphomycosis
  5. E. No diagnostic significance

Correct answer: E – No diagnostic significance

The presence of Candida in sputum often represents colonization rather than invasive pulmonary candidiasis. Diagnosis of pulmonary candidiasis requires evidence from tissue biopsy, not just sputum examination.

Q11: Which statement about phaeohyphomycosis is correct?

  1. A. The infection only occurs in immunocompetent patients
  2. B. Infected tissue reveals branching, septate nonpigmented hyphae
  3. C. The causative agents are members of normal microbial flora
  4. D. Phaeohyphomycosis may exhibit several clinical manifestations including subcutaneous or systemic disease, as well as sinusitis
  5. E. Cases rarely respond to treatment with itraconazole

Correct answer: D – Phaeohyphomycosis may exhibit several clinical manifestations including subcutaneous or systemic disease, as well as sinusitis

Phaeohyphomycosis has a wide clinical spectrum. Infected tissue reveals darkly pigmented hyphae. While opportunistic, it can occur in immunocompetent individuals. Itraconazole is an effective treatment.

Q12: All of the following are zoophilic dermatophytes — select all:

  1. A. Microsporum canis
  2. B. Trichophyton equinum
  3. C. Trichophyton simii
  4. D. Microsporum nanum

Correct answer: A – Microsporum canis

Microsporum canis (dogs/cats), Trichophyton equinum (horses), Trichophyton simii (monkeys), and Microsporum nanum (pigs) are all zoophilic dermatophytes.

Q13: What is the most reliable laboratory method for the isolation of Trichophyton rubrum?

  1. A. Blood culture
  2. B. Serological methods
  3. C. Skin scrapings microscopic examination using KOH
  4. D. Urease test

Correct answer: C – Skin scrapings microscopic examination using KOH

Microscopic examination of skin scrapings with KOH is the most reliable and practical first-line diagnostic test for dermatophytosis, including Trichophyton rubrum.

Q14: Which of the following dermatophytes does NOT have the spore form characteristic called Microconidia?

  1. A. Microsporum spp
  2. B. Epidermophyton spp
  3. C. Trichophyton spp
  4. D. Blastomyces spp

Correct answer: B – Epidermophyton spp

Epidermophyton floccosum produces only macroconidia and lacks microconidia, which is a key distinguishing laboratory feature.

Q15: Aflatoxins are a serious problem because:

  1. A. People often ingest them by mistaking the mushroom for an edible one
  2. B. They are potent carcinogens
  3. C. They are produced as a byproduct by Aspergillus niger
  4. D. They contaminate foodstuffs like peanuts and cottonseed oil
  5. E. None of the above

Correct answer: B – They are potent carcinogens

Aflatoxins are potent hepatocarcinogens, which makes them a significant global public health concern.

Q16: More visible symptoms of fungal infection are appearing recently because:

  1. A. More people live in areas with endemic organisms
  2. B. Pathogens have mutated to increased virulence
  3. C. New pathogens are being identified
  4. D. More people have suppressed immune systems
  5. E. All of the above

Correct answer: E – All of the above

The increase in visible fungal infections is multifactorial, including environmental changes, pathogen evolution, identification of new species, and a growing population with compromised immune systems.

Q17: Aflatoxins are produced by which fungus?

  1. A. Aspergillus parasiticus/flavus
  2. B. Aspergillus niger
  3. C. Penicillium marneffei
  4. D. Candida albicans

Correct answer: A – Aspergillus parasiticus/flavus

Aflatoxins are produced by Aspergillus parasiticus and Aspergillus flavus.

Q18: Which of the following is NOT a characteristic of histoplasmosis?

  1. A. Person to person transmission
  2. B. Specific geographic distribution
  3. C. Yeasts in tissue
  4. D. Mycelial phase in the soil

Correct answer: A – Person to person transmission

Histoplasmosis is not transmitted from person to person. It is acquired by inhaling spores from the mycelial phase found in soil, particularly associated with bird and bat droppings.

Q19: Immunocompromised persons suffer from several fungal diseases. Which is LEAST frequently associated?

  1. A. Cryptococcus neoformans
  2. B. Aspergillus fumigatus
  3. C. Malassezia furfur
  4. D. Mucor species

Correct answer: C – Malassezia furfur

Malassezia furfur typically causes superficial skin infections in immunocompetent individuals and is the least virulent among the listed fungi in immunocompromised hosts.

Q20: Each of the following statements concerning Candida albicans is correct EXCEPT:

  1. A. C. albicans is a budding yeast that forms pseudohyphae when it invades tissue
  2. B. C. albicans causes thrush
  3. C. C. albicans is transmitted primarily by respiratory aerosol
  4. D. Impaired cell-mediated immunity is an important predisposing factor to disease

Correct answer: C – C. albicans is transmitted primarily by respiratory aerosol

Candida albicans is primarily transmitted through direct contact with mucous membranes or skin, or via endogenous flora. Respiratory aerosol transmission is not the primary mode.

Q21: Each of the following statements concerning Cryptococcus neoformans is correct EXCEPT:

  1. A. Its natural habitat is the soil, especially associated with pigeon feces
  2. B. Budding yeasts are found in the lesions
  3. C. The initial site of infection is usually the lung
  4. D. Pathogenesis is related primarily to the production of exotoxin A

Correct answer: D – Pathogenesis is related primarily to the production of exotoxin A

The pathogenesis of Cryptococcus neoformans is related to its polysaccharide capsule, melanin, and urease, not exotoxin A. Exotoxin A is produced by Pseudomonas aeruginosa.

Q22: Natural habitat for Paracoccidioides brasiliensis is:

  1. A. Soil
  2. B. Water
  3. C. Mud
  4. D. Skin

Correct answer: A – Soil

The natural habitat for Paracoccidioides brasiliensis is soil.

Q23: Coccidioidomycosis is also called:

  1. A. Death fever
  2. B. Valley fever
  3. C. Chache fever
  4. D. Black fever

Correct answer: B – Valley fever

Coccidioidomycosis is also known as Valley fever.

Q24: One of the most common mycotoxins that infects nuts and grains and causes severe reactions is:

  1. A. Aflatoxins
  2. B. Aspergillus
  3. C. Actinomyces
  4. D. E. coli

Correct answer: A – Aflatoxins

Aflatoxins are common mycotoxins that infect nuts and grains and can cause severe reactions.

Q25: Coccidioides immitis can exist as molds in soil and spherules in tissues. This characteristic makes it:

  1. A. Diploid
  2. B. Diplococcus
  3. C. Dimorphic
  4. D. Polymorphic

Correct answer: C – Dimorphic

The ability of Coccidioides immitis to exist in two distinct forms (mold in soil and spherules in tissues) classifies it as dimorphic.

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