Hepatitis A transmission occurs in situations where an individual enters into oral contact with the feces of someone who carries the virus. This can happen in a variety of contexts, including kitchens in which a hepatitis A carrier is working to prepare food or is in contact with dishes, households in which children who are still in diapers are present, and through sexual behavior. While it is possible for hepatitis A transmission to occur through exposure to an infected person's blood, this is unusual.
A common scenario for hepatitis A transmission is one in which an infected person fails to wash her hands after using the toilet and then handles or serves food to others. A small amount of fecal matter may end up in the food or on serving dishes or eating utensils, which is then ingested by others. Those who consume the contaminated food or drink may then become infected with hepatitis A. Transmission may also take place in households or institutions in which residents are still in diapers, as both those who wear and change the diapers may spread the virus through handling of the diapers or feces. Good hand-washing practices can go a long way toward preventing this sort of hepatitis A transmission.
It is also possible for hepatitis A transmission to be the result of exposure to water contaminated with hepatitis A. While this may be unusual in most of the developed world where water purification and hygiene standards are carefully regulated, waterborne transmission of hepatitis A can happen in the developing world where standards are either nonexistent or laxly enforced. In some of these places, raw sewage may be routinely dumped into water sources from which seafood is harvested. Individuals who eat this seafood, particularly if it is served raw or rare, may be vulnerable to infection. Hepatitis A transmission may also occur when an individual drinks untreated, contaminated water or eats raw, unpeeled produce that has been exposed to infected water.
Transmission may occur as a result of sexual behavior, particularly any behavior that involves oral-anal contact. Individuals can protect themselves from sexual hepatitis A transmission by avoiding sex with infected partners and using dental dams and condoms during sex. Hepatitis A transmission through contact with blood is rare, though there remains some risk to those who handle blood or who share hypodermic needles with those who have the condition.