Hepatitis A is an infection of the liver caused by the hepatitis A virus (HAV). Spread through contaminated food and water or close person-to-person contact, the infection is a “one time” self-limited disease that rarely results in serious liver disease or death.
The hepatitis A virus is more prevalent in areas of low socioeconomic status where a lack of adequate sanitation and poor hygienic practices are common and children are often transmitters of the virus. Improvements in hygiene, public health policies and water supplies have greatly reduced the number of cases of hepatitis A worldwide.
Immunization against HAV virus has been available since 1995 and is now part of the childhood recommended immunization schedule.
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Fast facts on hepatitis A
Here are some key points about hepatitis A. More detail and supporting information can be found in the main article.
- The hepatitis A virus was first identified in 1973
- Person-to-person contact is the most common means of transmission and is generally limited to close contacts
- Hepatitis A rates in the US have declined by 95% since the hepatitis A vaccine first became available in 1995
- In 2006, HAV vaccination was incorporated into the US routine childhood vaccination schedule
- Hepatitis A is the most frequent vaccine-preventable disease in travelers
- HAV is one of the most frequent causes of foodborne infection
- Virtually any food can be contaminated with HAV, particularly shellfish and vegetables
- Casual contact among people does not spread the virus
- Foodborne or waterborne HAV outbreaks are relatively uncommon in the US
- Improved sanitation and the HAV vaccine are the most effective ways to combat the disease
- In developing countries with poor sanitary conditions and hygienic practices, 90% of the population have often been infected with HAV before the age of 10 years
- The single most important factor that determines the severity of illness from HAV is age; those aged 50 and above have a higher chance of adverse events from the infection.
What is hepatitis A?
Hepatitis A is a virus that affects the liver and is most prevalent in areas with low standards of hygiene.
Hepatitis A is a virus that infects the liver, causing inflammation. The majority of infected adults develop symptoms 2 weeks after exposure.
Unlike hepatitis B and C, HAV infection does not cause chronic liver disease and is rarely fatal. People who have been infected become immune to HAV for the rest of their lives.
Hepatitis A has a worldwide distribution and is most prevalent in resource-poor regions where there is overcrowding, poor sanitation and a lack of reliable clean water resources. The virus survives for extended periods in seawater, fresh water, wastewater and soil.
Residents of Africa, Asia, and South America show nearly universal evidence of past infection. Exposure in early childhood is the norm in these regions, and most children never exhibit symptoms of the disease.
Causes of hepatitis A
The HAV is excreted in the stool (feces) of people with hepatitis A infection. The virus is transmitted from person-to-person through the fecal-oral route; that is when an uninfected person ingests food or water that has been contaminated with the feces of an infected person.
For the majority of hepatitis A infections, transmission occurs as a result of close personal contact with an infected household member or sex partner.
There are sporadic cases of foodborne hepatitis A outbreaks scattered across the US and are likely caused by HAV-infected food handlers who prepare food for a large social event (such as a wedding). A single HAV-infected food handler can transmit HAV to dozens or even hundreds of people and cause a substantial economic burden to public health.
HAV can remain infectious on environmental surfaces even after 1 month. The virus is killed by heating to over 185 °F (85 °C) for 1 minute. Adequate chlorination of water, as recommended in the US, kills any HAV that enters the water supply.
Risk factors for hepatitis A
The most common reported risk factor for hepatitis A in the US is international travel (up to 50% of cases), mainly to Mexico and Central and South America. Anyone who has not been vaccinated or previously infected can contract hepatitis A.
Others factors that increase the risk of developing hepatitis A infection include:
- Sexual and household contact with another person with hepatitis A
- Being a resident or staff in a small community residence setting
- Being a child or employee in a daycare center
- Homosexual activity in men
- Injectable drug use
- Exposure to food or waterborne outbreaks.
Routine vaccination of all infants began in 1999. In 2006, the Centers for Disease Control and Prevention (CDC) recommended expanding vaccination for all children in the US aged 12-23 months; this practice resulted in a 90% reduction in the number of cases of HAV infection. Infections will most likely occur in high-risk individuals or adolescents who missed the vaccination implementation.
On the next page, we look at the symptoms of hepatitis A, how hepatitis A is diagnosed, and the available treatment and prevention strategies for the condition.
Source: Hepatitis A: Causes, Symptoms and Treatment : Medical News Today
