About Viral Hepatitis
Viral hepatitis is an inflammation of the liver caused by infection by one of several viruses designated hepatitis A-E.
Hepatitis A and E virus are transmitted through contaminated food and water. Hepatitis B, C and D virus are blood-borne viruses, and can also be transmitted from mother to child at the time of birth (especially hepatitis B), and also through sexual contact. All these viruses can cause chronic infection, which may lead to liver cirrhosis and liver cancer.
The World Health Organization (WHO) estimates that over 300 million people are chronically infected with hepatitis B or C virus and 1.4 million people die each year from the various forms of viral hepatitis. Approximately 450,000 Australians are living with chronic viral hepatitis and around 1,000 people die as a result of it each year.
Hepatitis A is spread by contaminated food and water, and from person to person via faecal-oral transmission. Although hepatitis A can cause significant illness, the body usually recovers without treatment and becomes immune to future infections. Vaccines can prevent hepatitis A; these are recommended for travellers and other groups at particular risk of infection. Apart from occasional outbreaks, most cases in Australia are associated with travel to endemic areas. A fundamental control modality for hepatitis A is sanitation and provision of a safe water supply.
This is the most prevalent form of viral hepatitis worldwide, and is the leading cause of liver cancer globally. An estimated 250 million people live with hepatitis B worldwide, and up to one quarter will die as a result of their infection without effective care. Around 230,000 Australians are thought to be living with chronic hepatitis B.
Most people living with chronic (long-term) hepatitis B acquired it at birth early in life. Following infection, the chance of developing chronic hepatitis B in infancy is around 90%, but falls to 5% among adults. A safe and highly effective vaccine has been available for hepatitis B since the 1980s. It has been provided for all infants born in Australia since May 2000. Globally, the program has prevented millions of deaths from liver cancer and liver cirrhosis. Hepatitis B can be transmitted from person to person through sex or blood-to-blood contact. Hepatitis B cannot be transmitted through hugging, kissing, sharing food and utensils for eating, insect bites, coughing, sharing bathroom and toilet facilities, or swimming pools. In some countries, hepatitis B is still transmitted via use of unsterile medical equipment or transfusion of unsafe blood.
Vaccination for all infants is recommended in Australia and the majority of countries globally, with coverage in 2017 reaching 84% of all children. In Australia, vaccination is also recommended for adults at greater risk of infection including household and sexual contacts of people living with hepatitis B; people who inject drugs; and health care workers.
Effective antiviral treatments are also available for chronic hepatitis B. These can prevent liver damage and liver cancer from occuring. But even in a well-resourced country such as Australia, only a minority of people needing treatment and care for hepatitis B are receiving it and there is high variation in uptake according to region within Australia. In 2015 WHO released guidelines for treatment and care of hepatitis B which provide the essential framework for developing treatment and care programs across all settings. Active research into cures for hepatitis B infection is underway.
An estimated 200,000 people live with chronic hepatitis C in Australia. Most hepatitis C infections in Australia were acquired through unsafe injecting drug use, however in some low-resource countries, ongoing transmission of hepatitis C in health care settings is a major problem. Around 80% of people infected with hepatitis C develop chronic infection; those who do clear the infection naturally remain susceptible to future infections. No vaccine for hepatitis C is available. On March 1 2016 in Australia, new treatments were listed on the Pharmaceutical Benefits Scheme. Although expensive, these treatments represent a huge advance and are a cost-effective way to prevent both new infections and deaths due to existing hepatitis C infections. With cure rates of the order of 90% with 8-24 weeks of tablets, and minimal side effects, these agents have the potential to drastically reduce the impact of hepatitis C. The real key to unlocking this potential is the very liberal access criteria the Commonwealth government has applied to these treatments. As a result, uptake of treatment for hepatitis C in Australia has risen more than 20-fold. Although the cost of these agents is prohibitive in some settings, much work is being done internationally to improve access and anyone with active infection should be considered for antiviral therapy. The most recent WHO guidelines on treatment and care for hepatitis C were released in 2016.
Hepatitis C is a blood-borne virus, and is only transmitted through blood-to-blood contact. The most common ways (highest risk) hepatitis C is transmitted are the sharing or re-use of unsterile injecting equipment, body art and piercing. Lower risk transmission of hepatitis C can be through mother to baby (around 5% of babies may acquire the virus from a mother who has hepatitis C), sexual transmission, unsterile medical and dental procedures, and the sharing of razor blades and other personal grooming aids.
Harm minimization and harm reduction strategies, such as provision of sterile injecting equipment through the needle and syringe programs, are essential for limiting the spread of hepatitis C.
Hepatitis D virus is a satellite virus that can only infect people who also have hepatitis B. It is estimated that approximately 5% of people living with hepatitis B globally also have hepatitis D, which can lead to more severe liver disease. Hepatitis D is transmitted in similar ways to hepatitis B, through blood or contact with contaminated blood products. Some regions worldwide are highly endemic for hepatitis D. Hepatitis D can be prevented through prevention of hepatitis B infection by vaccination. Prevention of hepatitis D superinfection can be achieved through education to reduce exposure to infectious blood.
Hepatitis E, like hepatitis A, is spread through contaminated food and water. The first outbreak of hepatitis E infection acquired in Australia was reported in 2016. While hepatitis E is usually relatively mild, it can cause serious illness late in pregnancy, with a death rate of up to 20% among pregnant women in their third trimester. A vaccine against hepatitis E has been developed but is currently licensed only in China.
As hepatitis E is spread through the faecal-oral route, prevention of hepatitis E relies primarily on the provision of clean drinking water and good personal hygiene. Travellers to endemic countries are advised to take precautions against drinking contaminated water, eating uncooked shellfish and uncooked fruits and vegetables, and be aware of personal hygiene including hand washing. There are no specific medications or treatment for hepatitis E, which is self-limiting in most cases.
The WHO Collaborating Centre for Viral Hepatitis is a research centre located within VIDRL at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia.
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