The five hepatitis viruses: A, B, C, D and E.

The five hepatitis viruses - A, B, C, D and E - are distinct; they can have different modes of transmission, affect different populations, and result in different health outcomes. While hepatitis B and hepatitis C cause the greatest global burden of disease, hepatitis A, hepatitis D, and hepatitis E are also global health concerns.

• Hepatitis A is primarily spread when someone who has never been infected with hepatitis A and is not vaccinated, ingests food or water that is contaminated with the feces of an infected person or has direct contact with someone who is infected. Hepatitis A does not cause chronic liver disease and is rarely fatal, but it can cause serious symptoms. Hepatitis A can be prevented through improved sanitation, food safety, and vaccination.
• Hepatitis B is spread through contact with blood or other body fluids of an infected person, including at birth from a mother to her baby and through sexual contact. The hepatitis B virus can cause both acute and chronic infection, ranging in severity from a mild illness lasting a few weeks to a serious, chronic illness. People who are chronically infected can develop liver cirrhosis or even liver cancer. Hepatitis B is most common in sub-Saharan Africa and east Asia, where between 5–10% of the adult population is chronically infected. Rates of chronic hepatitis B are also high in the Amazon region of South America, the southern parts of eastern and central Europe, the Middle East and the Indian subcontinent. Many people with chronic hepatitis B were infected at birth or during early childhood. Getting the hepatitis B vaccine is the most effective way to prevent hepatitis B virus infection. WHO recommends that all infants receive the hepatitis B vaccine as soon as possible after birth. In many parts of the world, widespread infant vaccination programs have led to dramatic declines of new hepatitis B cases.  
• Hepatitis C is spread through contact with blood of an infected person. Hepatitis C is common in many countries in the world; in much of Asia and Africa, most infections are caused by unsafe medical injections and other medical procedures. Hepatitis C related to injecting drug use occurs throughout the world; an estimated 67% of people who inject drugs having been infected with the hepatitis C virus. Mother-to-child transmission of hepatitis C is also possible. Hepatitis C, like hepatitis B, can also cause both acute and chronic infections, but most people who get infected develop a chronic infection. A significant number of those who are chronically infected will develop liver cirrhosis or liver cancer. Antiviral medicines can cure approximately 90% of people with hepatitis C, thereby reducing the risk of death from liver cancer and cirrhosis, but access to diagnosis and treatment is low. There is currently no vaccine for hepatitis C but research in this area is ongoing.
• Hepatitis D is passed through contact with infected blood. It only occurs in people who are already infected with the hepatitis B virus. People who are not already infected with hepatitis B can prevent hepatitis D by getting vaccinated against hepatitis B.
• Hepatitis E is spread mainly through contaminated drinking water. Hepatitis E usually clears in 4-6 weeks so there is no specific treatment. However, pregnant women infected with hepatitis E are at considerable risk of mortality from this infection.  Hepatitis E is found worldwide, but the number of infections is highest in East and South Asia. Improved sanitation and food safety can help prevent new cases of hepatitis E. A vaccine to prevent hepatitis E has been developed and is licensed in China, but is not yet available elsewhere.

FONTE: CDC