Virus Quiz : Test your knowledge

1. In the natural history of many viral diseases, a “prodromal phase” refers to:

1. The period after complete recovery when no virus is present.
2. The early, non-specific symptoms preceding the characteristic features of the disease.
3. The time between infection and first entry of virus into the bloodstream.
4. The final stage characterised only by specific organ failure.

2. Which of the following changes would most likely favour the emergence of a viral pandemic?

1. Decrease in international travel and trade.
2. High R₀ and significant proportion of asymptomatic transmission.
3. Virus restricted strictly to a rare animal host with no human infection.
4. Very short infectious period with no respiratory shedding.

3. With reference to viral entry into host cells, which of the following mechanisms is/are correctly matched?

1. Receptor-mediated endocytosis – Common route for many enveloped and non-enveloped viruses.
2. Direct fusion at the plasma membrane – Typically used by some enveloped viruses.
3. Passive diffusion through the lipid bilayer – Main route for all large DNA viruses.

Select the correct answer using the code below:

1. 1 only
2. 1 and 2 only
3. 2 and 3 only
4. 1, 2 and 3

4. In many viral infections, “immune escape” may occur due to:

1. Rapid mutation of viral epitopes recognised by antibodies and T cells.
2. Downregulation of MHC molecules on infected cells.
3. Production of viral proteins that mimic host regulatory molecules.

Which of the statements given above is/are correct?

1. 1 only
2. 1 and 2 only
3. 1, 2 and 3
4. 2 and 3 only

5. With reference to “post-exposure prophylaxis” (PEP) for certain viral infections, which of the following is/are generally true?

1. It may involve administration of specific immunoglobulin.
2. It may include initiation or completion of a vaccine series.
3. It is effective only if the virus has already caused irreversible organ damage.

Select the correct answer using the code below:

1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3

6. Which of the following best distinguishes a “vector-borne” viral infection from a “direct-contact” viral infection?

1. Presence of a non-human arthropod intermediary that is essential for transmission.
2. Absolute absence of human-to-human transmission in all circumstances.
3. Obligatory replication of the virus within the arthropod vector.
4. Requirement of contaminated food or water as the only route of spread.

7. In the context of surveillance for emerging viral infections, a “sentinel surveillance system” primarily aims to:

1. Test every individual in the population for a virus.
2. Use selected sites or groups to monitor trends and early signals of disease.
3. Guarantee elimination of the virus within one incubation period.
4. Track only mortality data without recording cases.

8. With reference to “basic reproduction number” (R₀) of a virus, which of the following statements is/are correct?

1. It is defined for a completely susceptible population.
2. If R₀ < 1, the infection tends to die out in the long run.
3. R₀ depends on both biological properties of the virus and population contact patterns.

Select the correct answer using the code below:

1. 1 and 2 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

9. In an outbreak investigation of a viral disease, which one of the following steps is usually undertaken FIRST?

1. Implementation of nationwide vaccination campaigns.
2. Laboratory sequencing of all viral isolates.
3. Verification of the diagnosis and confirmation that an outbreak exists.
4. Drafting international treaties to restrict travel.

10. A viral disease targeted for eradication must ideally have all of the following characteristics, EXCEPT:

1. Humans are the only significant reservoir.
2. Effective, long-lasting immunity after vaccination or infection.
3. Availability of a sensitive and specific diagnostic test.
4. Frequent subclinical infection with numerous non-human reservoirs.