Virus Quiz : Test your knowledge

1. For a viral infection, “secondary attack rate” in a household study most appropriately measures:

1. Proportion of all city residents infected.
2. Proportion of susceptible household contacts who become infected after exposure to a primary case.
3. Proportion of cases that require hospitalization.
4. Proportion of infected individuals who die.

2. Which of the following features is MOST likely to promote establishment of a chronic viral infection in humans?

1. Strict lytic replication that rapidly kills host cells.
2. Ability to integrate into host genome or persist in long-lived cells with immune evasion.
3. Absolute dependence on environmental replication outside the host.
4. Replication only in enucleated red blood cells.

3. With reference to “viral quasispecies”, which of the following is/are correct?

1. They represent a swarm of closely related viral genomes within a host.
2. They arise due to high mutation rates during replication.
3. They imply that all virions are genetically identical.

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 an epidemic curve of a viral disease, a “point-source outbreak” is MOST likely suggested by:

1. Multiple peaks separated by one or more incubation periods.
2. Sharp single peak with most cases occurring within one incubation period.
3. Constant low-level incidence over many years.
4. Absence of any new cases after the index case.

5. “Viral fitness trade-off” in evolution often implies that:

1. Increasing transmissibility may reduce other fitness components such as virulence or environmental stability.
2. Viruses can maximize all fitness traits simultaneously without limitation.
3. Mutation always makes viruses less fit.
4. Only DNA viruses experience trade-offs.

6. With reference to “sterilizing immunity” against a virus, which one of the following is correct?

1. It prevents disease but not infection.
2. It prevents both infection and disease by rapidly neutralizing the virus upon exposure.
3. It applies only to bacterial pathogens.
4. It always lasts for the lifetime of the host.

7. In a viral infection, detection of IgM antibodies typically suggests:

1. Past infection many years ago only.
2. Recent or current infection.
3. Presence of only maternal antibodies.
4. Complete absence of active infection.

8. In the context of influenza-like viral infections, “seasonality” can be influenced by all of the following, EXCEPT:

1. Changes in human indoor crowding and behavior.
2. Temperature and humidity affecting viral stability in air.
3. School calendar and contact patterns.
4. Universal constant R₀ that never changes with environment.

9. For a virus primarily transmitted via contaminated food, which intervention most directly targets the “source” in the classical epidemiologic triad?

1. Personal hand hygiene alone.
2. Identifying and excluding infected food handlers or contaminated food items from distribution.
3. Using insecticide-treated nets.
4. Mandating mask use in public transport.

10. During vaccine rollout for a novel virus, “phase IV (post-marketing) surveillance” is crucial primarily to:

1. Determine basic laboratory safety of the vaccine.
2. Detect rare adverse events and monitor long-term effectiveness in real-world use.
3. Replace all earlier clinical trial phases.
4. Ensure that no further data are collected after licensure.