Viral hepatitis is inflammation of the liver caused by hepatotropic viruses — viruses with a particular affinity for liver cells. It is not one disease but a family: five distinct viruses, hepatitis A, B, C, D and E (HAV, HBV, HCV, HDV and HEV), produce a clinically similar illness through different virological and epidemiological routes. Before serological tests (blood tests for virus-specific antigens and antibodies) were available, the viral causes were not obvious from the clinical and epidemiological features alone; only after serological tests became available could they be distinguished.
The liver injury is immune-mediated rather than caused by the viruses killing hepatocytes (liver cells) directly. The acute form is defined as resolution of symptoms before 6 months. All five viruses can cause acute hepatitis; HBV, HCV and HDV can also cause chronic hepatitis in a proportion of cases, and HEV mostly causes an acute illness, though some of its genotypes can cause chronic disease.
Where to start
A clinician meets viral hepatitis through a series of questions: how the viruses reach a patient, how they injure the liver, what the illness looks like, how it is confirmed, what can go wrong, what else it could be, and how it is treated and prevented. A reader new to the topic can start with the first entry below and continue in order; a reader with one specific question can go straight to the matching entry.
- Transmission and Epidemiology of Viral Hepatitis — how each of the five viruses spreads, which groups are at risk, and how common chronic infection is.
- Pathogenesis of Viral Hepatitis — why the viruses do not damage liver cells directly, and how the immune response decides whether infection clears or persists.
- Clinical Presentation of Viral Hepatitis — the incubation period of each virus and the prodromal, icteric and recovery phases of the acute illness.
- Laboratory Diagnosis of Viral Hepatitis — the general laboratory picture of liver injury: enzymes, bilirubin, blood count and clotting.
- Serology of Viral Hepatitis — the virus-specific tests that identify the responsible virus and separate acute from chronic infection.
- Complications of Viral Hepatitis — fulminant hepatitis and the rarer complications.
- Differential Diagnosis of Viral Hepatitis — the infections, drugs and other conditions that mimic viral hepatitis.
- Treatment of Viral Hepatitis — supportive care for the acute illness and drug treatment for chronic hepatitis B, C and D.
- Prevention of Viral Hepatitis — vaccines, post-exposure prophylaxis and the measures that interrupt transmission.