Diagnostic Virology

Question 1

Sensitivity = ?

Answer 1

TP / (TP+FN)

TP+FN is the same as the number of people with the disease

Question 2

Specificity = ?

Answer 2

TN/(TN+FP)

Question 3

PPV = ?

Answer 3

TP/(TP+FP)

TP+FP is the same as all positive results

Question 4

What test is the first test used to screen a person for HIV?

Answer 4

ELISA

Question 5

An ELISA test that is positive for HIV will be followed by a Western blot. A western blot is more specific than ELISA. What do the HIV ELISA and Western blot detect?

Answer 5

HIV antibody

Question 6

What does cytopathic effect in tissue culture cells provide evidence of?

Answer 6

Infectious virus

Question 7

Many OBGYN doctors routinely screen sera for rubella antibody (IgG) on a woman’s first visit before she becomes pregnant. If a woman has no anti-rubella antibodies what is the recommended next step?

Answer 7

Advise mother to have the live attenuated vaccine, well before she becomes pregnant
Live attenuated rubella vaccine is not given to pregnant women