Hepatitis A virus is present in the feces of infected people and is most often transmitted by eating contaminated water or food. Most infections have only mild symptoms, and most people will fully recover and remain immune to the hepatitis A virus in the future. However, hepatitis A virus infection can also be serious and even life-threatening
Hepatitis B virus is transmitted through contact with infected blood, sperm and other body fluids. Hepatitis B virus can be transmitted to an infant through an infected mother at birth or through a family member to an infant in early childhood. The virus can also be transmitted by contaminating injections and injecting drugs in medical operations through the use of blood and blood products contaminated with hepatitis B virus.
Hepatitis C virus is also most often transmitted through contact with infected blood. The use of blood and blood products contaminated with hepatitis C virus, the use of contaminated injections and injecting drugs in medical operations may cause the spread of the virus.
Hepatitis D virus infection only occurs in people infected with hepatitis B virus. Double infection with hepatitis D virus and hepatitis B virus may cause more serious diseases and worse consequences. Safe and effective hepatitis B vaccine protects against hepatitis D virus infection.
Like the hepatitis A virus, the hepatitis E virus is mostly infected by eating contaminated water or food. In the developing world, hepatitis E virus is a common cause of hepatitis epidemics, and more and more developed countries recognize it as an important cause.