Hepatitis A is spread by direct or indirect contact with the feces of an infected person or by fecal contamination of food and water. In the United States, HAV occurs most often in restaurants and day care centers, and is a major health problem in developing countries where there is poor sanitation and overcrowding. Hepatitis B is spread through contact with infected body fluids, such as blood, semen, and vaginal secretions. It is most often transmitted via unprotected sexual contact, and is considered a sexually transmitted disease. It can also be passed by sharp objects contaminated with infected blood, such as hypodermic needles, ear or body piercing, tattooing, or by razors or toothbrushes.
Mothers can pass it to their newborns at birth or soon after.
Hepatitis C is most commonly spread through blood, primarily via contaminated needles. It is not easily transmitted through sexual contact or from mothers to their newborns. HCV is the cause of most of the existing transfusion-related cases of hepatitis, but has rarely been transmitted that way since 1990 when all donor blood began to be tested for the virus. In about 40 percent of HCV cases, the means of transmission is not known. In some cases, people with HAV do not have symptoms.