Question

1. What does it mean to say that HSV-1 is often latent?

It is always present in infected individuals, but lesions may be small or hidden

It is normally difficult to detect even when causing an active infection unless appropriate screening tests are conducted

It undergoes periods of inactivity when it resides in trigeminal nerve ganglia and does not cause symptoms

It undergoes cycles of rapid growth and slower growth, affecting the symptoms that can be observed

2. Which of the following is NOT a disease caused by a fungus?

thrush

coccidioidomycosis

“athlete’s foot”

carbuncles

3. The relatively mild viral disease that causes a rash on the trunk typically in infants and toddlers and is self limiting usually caused by human herpesvirus-6, or sometimes human herpesvirus-7, is better known as

chickenpox

fifth disease

measles

roseola

4. Inhalation of respiratory secretions is involved in the transmission of the following, EXCEPT

rubella

influenza

SARS

parvovirus

Answer 1

Ans 1: Correct option: It undergoes periods of inactivity when it resides in trigeminal nerve ganglia and does not cause symptoms

Explanation: In humans, this virus infects the oral mucosa. Then it enters into the trigeminal nerve ganglia and remains there as an inactive virus or as a latent virus. During this phase, no symptoms are observed hence the virus is called latent which means hidden.

The explanation for incorrect options:

1. Infectious virus is not produced during the latent phase. Thus no disease symptoms are observed during this phase.
2. The virus switches from an inactive latent phase to the active lytic phase. The disease symptoms like blisters are observed during the active phase. During this phase, the presence of the virus can be detected either by the culture test or by the antibody test.  
3. It switches between the completely inactive latent phase and the active lytic phase. No symptoms are observed during the latent phase.

Ans 2: Correct option: Coccidioidomycosis

Explanation: This disease is caused by coccidian protozoa. It is the intestinal tract disease of the animals.

The Explanation for incorrect options:

1. Thrush is caused by the fungus candida.
2. Athlete's foot is caused by the fungus tinea.
3. Carbuncle disease is caused by a bacterial or fungus. But it is mainly caused by a bacterial infection.

Ans 3: Correct option: Roseola

Explanation: This disease does not have very serious complications. It is a contagious disease but it does not spread rapidly.  

The explanation for incorrect options:

1. Chickenpox: This disease is caused by the varicella-zoster virus.
2. Fifth disease: This disease is generally observed in children and caused by parvovirus B19.
3. Measles: The paramyxovirus cause this disease.

Ans 4: Correct option: Parvovirus

Explanation: Transmission of parvovirus B19 also occurs through blood for example from the mother to baby during pregnancy.

The explanation for incorrect options:

All the diseases mentioned in the question can spread through respiratory secretions but only parvovirus B 19 is also transmitted through blood.