The Hepatitis A virus occurs through ingestion of fecally contaminated materials from an HAV positive source - another person, contaminated food, or contaminated water.
The Hepatitis A virus (HAV) infects liver cells causing inflammation of the liver (hepatitis). HAV belongs to a family of viruses known as Picornavirus. Among the picornaviruses, HAV is the only one that affects the liver. Other family members include the enteroviruses and rheoviruses that cause gastrointestinal infections, rhinoviruses that cause the common cold, and the virus responsible for foot and mouth disease in livestock – a diverse group to be sure!
HAV is responsible for 20-65% of all cases of acute hepatitis reported each year in adults. Transmission occurs person-to-person via the fecal-oral route – putting something into your mouth that has been contaminated by the feces of someone who is infected with HAV, and through ingestion of fecally-contaminated food and water. Once in the body, the virus enters the bloodstream and travels to the liver.
In North America, transmission is often indirect, with sporadic outbreaks occurring mostly through household and other areas of close contact such as schools, day-cares, and long-term-care facilities, as well as following consumption of foods handled by infected food handlers. Transmission also occurs through sexual exposure to an infected person. Transmission is common between children due to poor hygiene practices and sharing of toys – children also commonly transmit infection to adults in the household.
Contaminated water (fresh or seawater), shellfish (especially mussels and oysters) harvested from contaminated water sources, produce irrigated with contaminated water, and contaminated runoff to fields used for produce may be transmission sources. In developing countries, food-borne and water-borne infections are common, although the incidence of infection in adults native to these areas is uncommon due protection acquired through HAV exposure and infection during childhood. The risk for unprotected travelers to developing countries is estimated at 3-5 per 1,000 travelers. The risk of travel related transmission is higher in those who:
- visit rural areas,
- do not practice safe hygiene,
- do not practice food and water precautions.
Unprotected travelers include those who have not been previously infected or immunized with HAV vaccine, as infection results in immunity to future HAV infection.
Chlorination of water destroys hepatitis A, and although the HAV can live outside the body for months, it is killed by heating for one minute at 85 degrees C (185 degrees F).
In the U.S., HAV is the seventh most commonly reported infectious disease. As mentioned in an earlier blog, HAV infection, HAV affects approximately 150,000 people each year in the U.S. (CDC), and 1,000 - 3,000 people each year in Canada (Health Canada). It is likely that the incidence of HAV infection is underestimated due to under-reporting and asymptomatic carriage of the virus.
HAV causes flu-like symptoms, abdominal pain and jaundice (yellowing of skin and eyes). The virus has an incubation period of 3-5 weeks before the symptoms associated with acute infection occur. The progression of symptoms includes the sudden onset of fever, malaise (feeling unwell), loss of appetite, nausea and abdominal pain Infection varies in length from10-30 days for mild infections, and 3-5 weeks for severe, although most infections are mild and full recovery is common. Children are often asymptomatic.
Minimize your risk of HAV infection:
- Practice good personal hygiene.
- WASH YOUR HANDS!
- Follow recommended food and water precautions when traveling to endemic areas.
Food and water precautions: boil it, cook it, peel it or leave it.
