How Hepatitis Is Transmitted

There are many forms of hepatitis including viral hepatitis, autoimmune hepatitis, fatty liver hepatitis, alcoholic hepatitis, and toxin-induced hepatitis, which also means that there are many ways a person can contract or develop hepatitis.

The only form of hepatitis that can be spread from one person to another is viral hepatitis, but just how these viruses are transmitted is commonly misunderstood.

The Types of Viral Hepatitis

There are five main types of viral hepatitis known as hepatitis A (HAV), hepatitis B (HBV), hepatitis C (HCV), hepatitis D (HDV), and hepatitis E (HEV). That said, there have been cases of acute hepatitis that could not be attributed to one of these five types of hepatitis viruses, alcohol, drugs, or autoimmune disease, which lead researchers to try to find another cause.

Though the etiology of these viruses have not yet been fully established, researchers have identified three other types of viral hepatitis (and their associated viruses), which they have named hepatitis F (HFV) and hepatitis G (HFG). 

Some cases of hepatitis have been transmitted through blood transfusion, but this is a rare mode of transmission. The hepatitis viruses, and some other viruses, comprise a set of pathogens called transfusion-transmitted viruses (TTV)'.

As relatively new diseases and viral discoveries, information about them and how they work is relatively scarce. We do know, however, that cases of TTV have only been associated with hepatitis in people who have had a blood transfusion.

Enteric Routes: Transmission of Hepatitis A and Hepatitis E

The Hepatitis A and hepatitis E viruses (HAV and HEV) are both transmitted by enteric, that is digestive or by fecal, routes. This is also known as the fecal-oral route.

To be exposed to these viruses, you must ingest fecal matter that is infected with the virus. While there are several ways in which this fecal-oral route can be established, poor hygiene and poor sanitary conditions in some countries lead to higher rates of infection of these viruses.

As a result, some areas of the world, like India, Bangladesh, and Central and South America, are particularly prone to the hepatitis E virus. About one-third of people in the United States have been exposed to the hepatitis A virus.

It is believed that the hepatitis F virus (HFV) may also be spread by enteric routes.

Parenteral Routes: Transmission of Hepatitis B, Hepatitis D, and Hepatitis C

Hepatitis B, C, and D viruses (HBV, HCV, and HDV) are all transmitted by what is known as the parenteral route.

Parenteral simply means that these viruses can be introduced by all routes except through the intestinal tract, which leaves the door wide open in terms of possible exposure. Let's look at the possible transmission routes for each of these types of hepatitis virus more closely. 

How HBV Is Spread

It is possible for the hepatitis B virus to be spread through the bodily fluids of an infected person, which is to say that the virus can be transmitted through the blood, sweat, tears, saliva, semen, vaginal secretions, menstrual blood, and breast milk of an infected person.

Opportunities for exposure can include sharing a syringe or getting tattoos or body piercings with infected tools. But it also means that it is possible to be exposed during childbirth as well as sexual contact and intercourse. In fact, nearly two-thirds of acute cases of hepatitis B in the United States are caused by sexual exposure.

Though HBV can be spread through blood, there is generally very little risk of contracting the virus through blood transfusions these days, as blood is screened carefully.

How HCV Is Spread

The hepatitis C virus is transmitted primarily through blood to blood contact, meaning that a person can become infected with the virus should the blood of a person who carries the virus be introduced into another person's bloodstream.

Therefore, as with hepatitis B, blood transfusions (prior to 1990 in this case), tattooing and body piercing, occupational exposure, medical procedures, and intravenous drug use can all lead to possible exposure to the virus.

Unlike hepatitis B, however, sexual contact and childbirth have both been shown to be an inefficient route of exposure to HCV.

The hepatitis G virus is thought to be transmitted in a similar way to HCV.

Transmission of HDV

The hepatitis D virus is transmitted in the same way as hepatitis B. Hepatitis D, however, can only exist with the hepatitis B virus. HDV can be caught either at the same time as HBV (which is known as co-infection). This type of infection is known to clear the body well (90% to 95%). Others get the hepatitis D virus separately when they are already infected by HBV (which is known as superinfection). In these cases, 70% to 95% go on to have a more serious chronic form of hepatitis D.

Read more about signs and symptoms of hepatitis.