Overview of hepatitis types A, B, C, D and E
The hepatitis A virus is found in the faeces of infected persons. It is most often transmitted through consumption of contaminated water or food. Hepatitis A virus infection causes no or mild symptoms in many cases, especially in childhood. Most people make a full recovery and remain immune from further hepatitis A virus infection. However, hepatitis A virus infections can also be severe and life-threatening. Most people living in areas of the world with poor sanitation, especially in rural areas, have been infected with hepatitis A. People living in many urban areas in the Western Pacific Region have also been infected.
The hepatitis B virus is transmitted through infected blood, semen and other bodily fluids. Hepatitis B can be transmitted from infected mothers to infants at the time of birth, or from family members to children in the household. Transmission may also occur through transfusions of hepatitis B-contaminated blood and blood products, contaminated injections during medical procedures, and through sexual activities and injecting drug use. Health-care workers who sustain accidental needlestick injuries while caring for patients infected with hepatitis B are also at risk.
The hepatitis C virus is mostly transmitted through infected blood. This may happen through transfusions of hepatitis C-contaminated blood and blood products, contaminated injections during medical procedures, and through injecting drug use. Sexual transmission is also possible, especially when a person is infected with both hepatitis C and HIV; however this is less common.
Hepatitis D virus infections occur only in those who are infected with hepatitis B. When infected with both hepatitis D and hepatitis B, a person can be more seriously ill and related liver diseases may also progress much faster.
The hepatitis E virus is mostly transmitted through consumption of contaminated water or food. Hepatitis E is a common cause of hepatitis outbreaks in low- and middle-income countries and is also increasingly recognized as an important cause of disease in high-income countries.