Page 22 - Clinical Biochemistry 08PB804

• Hepatitis A (formerly known as infectious hepatitis) is an acute infectious disease of the
liver caused by the hepatitis A virus (HAV).

• It is a Picornavirus, it is non-enveloped and contains a single-stranded RNA.

• It is most commonly transmitted by the fecal-oral route via contaminated food or drinking
water. The incubation period is between two and six weeks.

• Hepatitis A is not progressive, does not have a chronic stage and does not cause permanent
liver damage.

• Following infection, the immune system makes antibodies against HAV that confer
immunity against future infection.

• The disease can be prevented by vaccination, and hepatitis A vaccine has been proven
effective in controlling outbreaks worldwide.

Diagnosis

• Specific diagnosis is made by the detection of HAV-specific IgM antibodies in the blood.

• IgM antibody is only present in the blood following an acute hepatitis A infection.

• It is detectable from one to two weeks after the initial infection and persists for up to 14
weeks.

Hepatitis B virus

• Hepatitis B is an infectious illness caused by hepatitis B virus (HBV).

• It is a DNA virus and it has a circular genome composed of partially double-stranded
DNA.

Unlike hepatitis A, hepatitis B does not generally spread through water and food. Instead, it is
transmitted through body fluids.

Diagnosis

• Assays for detection of hepatitis B virus infection involve serum or blood tests that detect
either viral antigens (proteins produced by the virus) or host antibodies.

• The hepatitis B surface antigen (HBsAg) is most frequently used to screen for the presence
of infection.