Curriculum · Gastroenterology
Acute viral hepatitis
What it is
Acute viral hepatitis is liver injury caused by the hepatitis viruses A to E and the herpes group. Hepatitis A is an RNA virus, typically a benign, self-limiting disease with a serious outcome being very rare, and it has no carrier state and does not cause chronic disease. Hepatitis E is spread by the faecal-oral route and causes a similar disease to hepatitis A, but it carries a significant mortality of about 20% during pregnancy, and it does not cause chronic disease or an increased risk of hepatocellular cancer. Hepatitis D is an incomplete RNA virus that requires hepatitis B surface antigen to complete its replication and transmission cycle, and it is transmitted in a similar fashion to hepatitis B by the exchange of bodily fluids. The two viruses differ in build: hepatitis B is a DNA virus with an envelope, while hepatitis A is a non-enveloped, single-stranded RNA virus. The incubation period of hepatitis E is 3-8 weeks.
How it presents
Hepatitis A is associated with the abrupt onset of fatigue, anorexia, malaise, nausea, vomiting and jaundice. Its presentation is flu-like symptoms, abdominal pain that is typically right upper quadrant, tender hepatomegaly, jaundice, and both hepatocellular and cholestatic liver function tests. In developing countries the childhood disease is 30% symptomatic while an infected adult is 70% symptomatic, and there may be prolonged cholestasis: fatigue, nausea, headache and myalgias first, then right upper quadrant pain and jaundice later. The incubation period of hepatitis A is reported as 2-4 weeks in one source and as 15-50 days in another, and transmission is by faecal-oral spread, often in institutions, through food or water. The symptoms of acute hepatitis B are similar to those of acute hepatitis A, though persons with hepatitis B may have anicteric or subclinical acute infection; hepatitis B is transmitted by exposure to the blood or body fluids of an infected person, including injection drug use, sexual contact, or transmission by an infected mother to her infant during delivery. Fever in a returning traveler puts hepatitis A on the list at 3% to 6% of cases, behind malaria at 27% to 42%, respiratory tract infection at 2.6% to 24%, diarrhea or dysentery at 4.5% to 14% and dengue at 2% to 8%, and ahead of enteric fever at 1.5% to 3%, UTI or pyelo at 2% to 4%, rickettsial at 0.5% to 2% and tuberculosis at 0.4% to 1%.