Viral hepatitis is an inflammation of the liver caused by one of the five hepatitis viruses, referred to as types A, B, C, D and E. While all of these viruses cause liver disease, they vary significantly in terms of epidemiology, natural history, prevention, diagnosis and treatment.
Hepatitis A virus (HAV)
Hepatitis A virus (HAV) is usually transmitted by the faecal-oral route, either through person-to-person contact or ingestion of contaminated food or water. Certain sex practices can also spread HAV. Infections are in many cases mild, with most people making a full recovery and remaining immune from further HAV infections.
However, HAV infections can also be severe and life threatening. Most people in areas of the world with poor sanitation have been infected with this virus. Safe and effective vaccines are available to prevent HAV infection.
Hepatitis B virus (HBV)
Hepatitis B virus (HBV) is transmitted through exposure to infectious blood, semen, and other body fluids. HBV can be transmitted from infected mothers to infants at the time of birth, or from family members to infants in early childhood.
Transmission may also occur through unsafe sexual intercourse, transfusions of HBV-infected blood and blood products, contaminated injections during medical procedures, and sharing of needles and syringes among injecting drug users.
HBV also poses a risk to healthcare workers who sustain accidental needle-stick injuries while caring for HBV-infected people. A safe and effective vaccine is available to prevent HBV infection.
Hepatitis C virus (HCV)
Hepatitis C virus (HCV) is mostly transmitted through exposure to infectious blood. This may happen through transfusions of HCV-infected blood and blood products, contaminated injections during medical procedures, and sharing of needles and syringes among injecting drug users. Sexual or interfamilial transmission is also possible, but is much less common.
There is no vaccine against HCV. Both HBV and HCV can cause cancer to humans. Antiviral agents against HBV and HCV exist. Treatment of HBV infection has been shown to reduce the risk of developing liver cancer and death.
HCV is generally considered to be a curable disease but for many people this is not the reality. Access to treatment remains a constraint in many parts of the world. Hepatitis D virus (HDV) infections occur exclusively in persons infected with HBV. The dual infection of HDV and HBV can result in more serious disease and worse outcomes. The hepatitis B vaccine provides protection from HDV infection.
Hepatitis E virus (HEV)
Hepatitis E virus (HEV), like HAV, is transmitted through consumption of contaminated water or food. HEV is a common cause of hepatitis outbreaks in the developing world and is increasingly recognized as an important cause of disease in developed countries.
HEV infection is associated with increased morbidity and mortality in pregnant women and newborns. A safe and effective vaccine against HEV was licenced in January 2012 but is not yet widely available.
• Advocacy and raising awareness of all types of viral hepatitis infections help reduce transmission in the community.
• Safe and effective vaccines are widely available for the prevention of HAV and HBV infections and an HEV vaccine has recently been licenced in China.
• Implementation of blood safety strategies, including blood supplies based on voluntary non-remunerated blood donations, effective public education on blood donation, donor selection, and quality-assured screening of all donated blood and blood components used for transfusion can prevent transmission of HBV and HCV.
• Infection control precautions in health care and community settings can prevent transmission of viral hepatitis as well as many other diseases.
• Safe injection practices can protect against HBV and HCV transmission.
• Safer sex practices, including minimizing the number of partners and using barrier protective measures (condoms), protect against HBV and possibly against HCV transmission.
• Harm reduction practices for injecting drug users prevent HAV, HBV and HCV transmission.
• Occupational safety measures prevent transmission of viral hepatitis to health care workers.
• Safe food and water provide protection against HAV and HEV infections.