The A-B-Cs of Diagnosing Viral Hepatitis in General Practice

The A-B-Cs of Diagnosing Viral Hepatitis in General Practice

by Dr Stella Pendle

In Australia, GPs are uniquely placed to manage patients living with hepatitis and play an important role in reducing the impact of chronic hepatitis in the community. Due to the often sensitive nature of the condition, GPs have a greater chance of identifying individuals living with viral hepatitis.

Hepatitis can be caused by the classical hepatitis viruses (hepatitis A, hepatitis B, hepatitis C, hepatitis D, and increasingly, hepatitis E) as well as other viruses (especially CMV and EBV).

Briefly outlined in this article are five common viruses, and how our pathology services can help you diagnose your patients suffering from hepatitis.

Hepatitis A

Hepatitis A is transmitted by the faecal–oral route through close person-to-person contact or after ingestion of food or water contaminated by the hepatitis A virus (HAV). Being a small non-enveloped virus, it can withstand environmental stress and maintain its infectivity. The incubation period is usually 30 days, but can be between 15 to 50 days.

It usually does not cause chronic infection, but in patients who are immunosuppressed, prolonged viral replication can be observed. While usually self-limiting, patients with other liver pathology may present with severe disease.

Diagnosis & Prevention:
The diagnosis of hepatitis A may be established by serological testing.

If acute hepatitis A infection is suspected, request HAV IgM, as this is a marker of acute infection. For routine screening or immunisation status HAV total antibody (HAV Ab) should be requested. Hepatitis A vaccination is recommended for travellers to endemic countries and other high risk groups, e.g. men who have sex with men. Routine serology testing after HAV vaccination is not recommended.

Hepatitis B

Hepatitis B virus (HBV) can be transmitted by contact with infected blood or body fluids containing the virus, including semen and saliva, or by contaminated needles. The incubation period is usually 45 to 180 days. HBV may also be transmitted vertically between an infected mother and her neonate, usually at the time of birth (vertical transmission).

Diagnosis & Prevention:
The majority of adults will recover with clearance of the virus from the blood after a few months. The development of chronic hepatitis B occurs when there is a failure of the immune response to eradicate the virus. A highly effective hepatitis B vaccine is available. Testing for HBV should be performed routinely as part of an antenatal screen on all pregnant women (request hepatitis B surface antigen - HBsAg). Serological testing for evidence of past or current hepatitis B can be performed on individuals at risk, including injecting drug users, sex industry workers, immunocompromised persons and migrants. Routine postimmunisation testing for hepatitis B is not recommended except in high risk groups.

Hepatitis C

Hepatitis C is transmitted through exposure to body fluids containing the hepatitis C virus (HCV). The incubation period can range from two weeks to six months, though a six to nine week incubation period is common. Chronic infection can occur in up to 70% of individuals while up to 30% will spontaneously resolve their infection. All persons with risk factors should have a serology test for HCV antibody. Both chronic carriers and those who have resolved the infection will remain HCV antibody positive for life.

Diagnosis & Treatment:
Because HCV is a major cause of chronic liver disease, cirrhosis and liver cancer, it is essential to diagnose chronically infected people so that treatment can be provided. Direct acting antiviral treatment for chronic hepatitis C is highly effective and well tolerated. Approximately 95% of patients will be cured. The treatment is available on the PBS and has a wide prescriber base that includes GPs.

Persons at risk of contracting a blood borne disease should be tested for hepatitis C as should persons with chronic liver disease or abnormal liver enzymes. Patients should be screened initially with a hepatitis C antibody test (HCV ab) and if this is positive, confirmed with a molecular test (HCV PCR) and genotyping.

Molecular testing for hepatitis C is also useful in diagnosing early acute infection when the serology may be negative or equivocal due to the long window period. This is a Medicare rebateable item, provided the test has not been performed in the previous 12 months. Genotyping may also be performed on HCV PCR positive patients who are awaiting treatment. There is currently no vaccination for hepatitis C, however people who have been diagnosed or are at high risk are recommended to be vaccinated against hepatitis A and B.

Hepatitis D

Hepatitis D virus (HDV) also known as delta virus is only detectable in HBV infected individuals as it requires HBV to replicate. Transmission is the same as HBV but it is uncommon in Australia. It should be considered in chronic HBV carriers who have an exacerbation of their liver disease.

Hepatitis E

Hepatitis E virus (HEV) is transmitted by the faecal-oral route after ingestion of contaminated food and water. Although classically thought to be a disease seen in travellers returning from the developing world, it has been increasingly described in Europe especially in relation to pig farming and may be underdiagnosed in Australia. Hepatitis E infection is a serious disease in pregnancy and may lead to fulminant liver failure in up to 20% of cases.

Diagnosis:
Hepatitis E infection may be diagnosed by antibody testing followed by HEV PCR if other tests for hepatitis (A, B and C) are negative.

Diagnostic Recommendations

The provision of clinical notes greatly aids in the correct test assignment. Where it is unclear what tests should be performed, request “Hepatitis Serology” and the laboratory will assign testing based on the clinical notes.
• All of the serological testing can be performed on serum samples. PCR testing requires a dedicated tube.
• Please refer to the table below for guidance.

There are a range of tests available to diagnose viral hepatitis: