Viral hepatitis

The classic viral hepatitides

• Hepatitis A;
• Hepatitis B;
• Hepatitis C;
• Hepatitis D, syn. Delta virus
• Hepatitis E;

Hepatitis A and E are transmitted by the faecal oral route, which includes sexual oral-anal contact. Infection in young children may be asymptomatic. Hepatitis B, C and E are blood borne or sexually transmitted, including vertical transmission. Hepatitis B is highly infective and is known to be transmitted within families and between children by uncertain mechanisms.

Acute infection is characterised by an asymptomatic phase of viral replication followed by fever, malaise, anorexia, abdominal pain +/- jaundice. The symptoms preceding appearance of jaundice may be prolonged and mysterious. Clinical improvement may then follow onset of jaundice. The biochemical pattern is "always" hepatitic (ie high transaminases) as opposed to obstructive (ie high gamma glutamyl transferase and alkaline phosphatase) derangement of liver function tests.

Leucopenia is common. Anaemia and thrombocytopenia may be seen. An immune complex illness may be seen in hepatitis B and C infection, with a maculopapular rash and arthritis. Pancreatitis, myocarditis, pericarditis, pleural effusion and polyneuritis have also been reported with hepatitis B.

Fulminant hepatitis, defined as hepatic encephalopathy developing within 8 weeks of onset of symptoms or within 2 weeks of onset of jaundice, may complicate 10% of acute hepatitis A, especially where there is co-existing chronic hepatitis B or C. Can also be seen in hepatitis B, especially where there is co-existing hepatitis D infection.

Chronic hepatitis is not seen in hepatitis A infection but may develop in up to 90% of perinatally acquired hepatitis B and C. Older patients are less likely to develop chronic infection, which may be asymptomatic for many years.

Non-hepatitis virus viral hepatitis

• Cytomegalovirus - usually acute and mild. May become chronic in immunosuppressed.
• Epstein-Barr virus - abnormal liver function tests are commonly seen, but clinical jaundice is rare. Where jaundice does develop, it has a large cholestatic element and can be prolonged. Typical features of glandular fever are usually present.
• Herpes Simplex - rarely causes hepatitis but may affect the immunocompetent and can be severe with fever, high transaminases (50 times upper range of normal) but relatively low bilirubin, coagulopathy and encephalopathy^[1]. A rash is often not present so consider aciclovir for any suspected viral hepatitis with negative serology for hepatitis viruses.

In about 7% of suspected viral hepatitis no infecting organism will be identified. The main differential diagnoses are drug induced hepatitis (including herbal preparations) and autoimmune hepatitis.

Acute hepatitis A & B are formally notifiable. This is because public health interventions to limit further spread are possible as these infections are vaccine-preventable.

References