Virus Quiz : Test your knowledge

1. “Spillover risk” of a zoonotic virus is increased when:

1. Contact between humans and wildlife reservoirs is reduced.
2. Encroachment into wildlife habitats and wildlife trade intensify.
3. High biodiversity is completely preserved without human interference.
4. Strict biosecurity measures are implemented in farms and markets.

2. With reference to “viral immune evasion”, which of the following mechanisms is/are known?

1. Downregulation of MHC molecules on infected cells.
2. Antigenic variation of surface proteins.
3. Complete absence of any viral proteins in infected cells.

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

3. “Endemic equilibrium” for a viral infection in a population implies that:

1. The virus has been completely eliminated.
2. Incidence remains roughly constant over time due to a balance between new infections and loss of susceptibility.
3. No new infections occur, but seroprevalence rises.
4. Case fatality rate is zero.

4. In the context of respiratory viruses, “short-range droplet transmission” is primarily associated with:

1. Large droplets that fall quickly within 1–2 metres.
2. Tiny aerosol particles that remain airborne for hours across long distances.
3. Exclusive spread through contaminated food.
4. Spread only via blood transfusion.

5. With reference to “viral pathogenicity” and “virulence”, which of the following is correct?

1. Pathogenicity is the ability to cause disease, while virulence refers to the degree of severity among those who are diseased.
2. Both terms are exact synonyms with no distinction.
3. Virulence is defined only by transmission efficiency.
4. Pathogenicity applies only to bacteria, not viruses.

6. A respiratory viral infection shows high “secondary attack rate” in households but low attack rate in workplaces. Which is the MOST plausible explanation?

1. Household contacts involve prolonged close interactions in enclosed spaces.
2. Virus can replicate only during working hours.
3. Workplaces are always completely free of susceptible individuals.
4. Household members have complete natural immunity.

7. “Vaccine escape variant” of a virus MOST appropriately refers to a variant that:

1. Is completely unrelated genetically to any previous strain.
2. Shows reduced neutralization by antibodies induced by current vaccines.
3. Cannot infect vaccinated individuals at all.
4. Always causes milder disease in all hosts.

8. In many viral haemorrhagic fevers, severe manifestations (shock, bleeding) are often linked to:

1. Exclusive replication in red blood cells.
2. Viral effects on endothelial cells, immune dysregulation, and coagulation pathways.
3. Absence of any host inflammatory response.
4. Direct destruction of skeletal muscle only.

9. For a congenital viral infection (acquired in utero), which public health interventions are MOST directly relevant?

1. Vector control only.
2. Screening and managing infections in women of childbearing age and during pregnancy, plus vaccination where available.
3. Improving industrial workplace safety alone.
4. Wastewater surveillance only.

10. “End-point sterilization” of medical equipment to prevent viral transmission requires:

1. Cleaning with water only.
2. Use of methods (e.g., autoclaving, appropriate chemical sterilants) that reliably inactivate all forms of microorganisms including viruses.
3. Short exposure to room air.
4. Cooling below 0°C without any other procedure.