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23 Nov 2019

West Nile Virus is an arbovirus that can be transmitted by birds because they develop viremia when infected. In contrast, infected humans cannot spread the disease because they do not develop viremia. Why is viremia associated with the ability to transmit the disease?

a. If there are no (or only very few) viral particles in the blood, then they are not picked up by vectors feeding on the blood in sufficient amounts to cause infection.

b. The virus is only found within red blood cells if there is no viremia, so it cannot be spread by mosquitoes that do not consume those cells.

c. Direct contact with blood is required for infection. If there are no viral particles in the blood, then infection can't occur using this mechanism.

d. Because white blood cells are found in the blood, any virus in the blood would be attacked by the immune system. With no viral particles available for the immune system to attack, the virus cannot be spread.

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When someone gets a bone marrow transplant, they have to be quarantined and carefully protected from pathogens for a period of time afterward. Why?

	A.	Bone marrow produces the main cells involved in the specific immune response, so these patients are at special risk of infection until they build up enough marrow to produce sufficient cells.
	B.	Bone marrow produces blood cells, so they have insufficient circulation for a period of time so their immune system lacks the energy to fight off any infection.
	C.	Anytime a foreign substance, even someone else's bone marrow, is introduced to a body, there is an extra risk of infection.
	D.	A common complication of bone marrow transplants is infection, and doctor's don't want the infection to spread to others.
	E.	It's a traumatic procedure, and any extra stress on their body could kill them.

There is antibody-mediated and cell-mediated specific immunity. Which type of cells are primarily involved in the antibody-mediated immune response?

	A.	Macrophages
	B.	B cells
	C.	Complement proteins
	D.	T cells
	E.	Antigens

From the bacteria's perspective, why is it helpful that it produce diarrhea in people?

	A.	Because it gets the bacteria out of the person and, likely, into the next one
	B.	It's not helpful really. That's just what that toxin causes.
	C.	Because that quickly kills the person
	D.	Because it makes the patient too unpleasant to be around
	E.	Because there is no real treatment for that

Where do prions come from?

	A.	There are prion-like particles in the brain normally, and when these become abnormal they can cause disease.
	B.	Mosquitoes.
	C.	They are clumps which form from normal prion-like particles in the blood that travel to the brain.
	D.	They are introduced by infectious protozoa.
	E.	Contaminated water.

QUESTION 8: Which of the following is an unsuitable culture method for an animal virus?

A. Direct inoculation of virus onto blood agar

B. Live animal inoculation

C. Tissue culture method

D. Injection of virus into embryonated eggs

QUESTION 9: An elderly patient who contracted chickenpox as a child now has shingles as an adult. You explain to your patient that both diseases are caused by the same virus, which lays dormant in the body prior to reactivation. Based on this information, choose the true statement.

A. Infected host cells will carry a provirus until sufficient viral load has been reached.

B. Your patient's infection is best characterized as an acute, non-persistent infection.

C. Viral replication occurs as a steady, logarithmic increase over time.

D. During dormant periods, the virus exists episomally inside of infected host cells.

QUESTION 10: While hiking, your patient was bitten by a rabid raccoon. Your patient denies having any previous rabies vaccinations. Which of the following antiviral medications should be administered to your patient to prevent viral attachment to host cells?

QUESTION 11: A young patient who underwent surgical placement of depth electrodes for epilepsy treatment contracted a prion disease. Cortical electrode probes are known to be reused in patients. Based on this information, which of the following prion diseases did the young patient most likely contract?

A. Variant Creutzfeldt-Jakob Disease

B. Inherited Creutzfeldt-Jakob Disease

C. Sporadic Creutzfeldt-Jakob Disease

D. Iatrogenic Creutzfeldt-Jakob Disease

QUESTION 12: In the Spring of 2009, a novel H1N1 virus emerged that had a new combination of genes from pigs, humans, and birds. As a result, the virus spread quickly, resulting in a swine flu pandemic. Which of the following concepts explains why the outbreak occurred?

Hepatitis C is a chronic liver infection that can be either silent (with no noticeable symptoms) or debilitating. Either way, 80% of infected persons experience continuing liver destruction. Chronic hepatitis C infection is the leading cause of liver transplants in the United States. The virus that causes it is blood borne, and therefore patients who undergo frequent procedures involving transfer of blood are particularly susceptible to infection. Kidney dialysis patients belong to this group. In 2008, a for-profit hemodialysis facility in New York was shut down after nine of its patients were confirmed as having become infected with hepatitis C while undergoing hemodialysis treatments there between 2001 and 2008.

When the investigation was conducted in 2008, investigators found that 20 of the facilityâs 162 patients had been documented with hepatitis C infection at the time they began their association with the clinic. All the current patients were then offered hepatitis C testing, to determine how many had acquired hepatitis C during the time they were receiving treatment at the clinic. They were considered positive if enzyme-linked immunosorbent assay (ELISA) tests showed the presence of antibodies to the hepatitis C virus.

Health officials did not test the workers at the hemodialysis facility for hepatitis C because they did not view them as likely sources of the nine new infections. Why not?

Why do you think patients were tested for antibody to the virus instead of for the presence of the virus itself

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