Hepatitis B

A British anaesthetist working in the United Kingdom suffering a needle stick injury

with a bloody, hollow sharp from a patient known to have hepatitis B, has serum tests

at ten weeks post-inoculation. Which of the following is LEAST LIKELY to be found?

a) Positive for antibody to hepatitis B surface antigen

b) Positive for IgM for anti-hepatitis D virus

c) Positive for anti-hepatitis B surface antigen

d) Positive for hepatitis B virus DNA

e) Positive for hepatitis B e antigen

Answer: b

Explanation

Anti-hepatitis B surface antigen is found early in the disease and may test positive

before symptoms start. It often disappears from the blood during the recovery phase

from the disease, around five months after exposure. Hepatitis B e antigen (HBeAg) is

only detected when the virus is present. Once recovery starts and the viral load falls,

HBeAg levels drop off until it becomes undetectable at around the three-month stage. It

is often used to indicate whether a patient is infective. Hepatitis B virus DNA is

generally on the wane by the three-month stage but remains detectable longer than

HBeAg. It is a more sensitive test of the presence of hepatitis virus in the serum than

HBeAg. Both of these markers of the presence of virus may persist if the person goes on

to develop chronic contagious hepatitis B. Antibody to hepatitis B surface antigen

typically is found from 24 weeks after exposure. However, it is also found following

immunisation with hepatitis B vaccine, which is widespread throughout British healthcare

workers at high risk of needle stick injury. Hepatitis D infection may be detected

by testing for IgM that is anti-hepatitis D virus. Hepatitis D is found in patients with

hepatitis B, so infection with hepatitis B puts a person at risk of concomitant infection

with hepatitis D. In a recent study, however, only 13% of hepatitis B positive patients

tested positive for hepatitis D.