Hepatitis is an inflammation of the liver, most commonly caused by a viral infection. There are five main hepatitis viruses, referred to as types A, B, C, D and E.
Hepatitis A and E are typically caused by ingestion of contaminated food or water. Hepatitis B, C and D usually occur as a result of parenteral contact with infected body fluids (e.g. from blood transfusions or invasive medical procedures using contaminated equipment). Hepatitis B is also transmitted by sexual contact.
The symptoms of hepatitis include jaundice (yellowing of the skin and eyes), dark urine, extreme fatigue, nausea, vomiting and abdominal pain.
Hepatitis A
Key facts
* Hepatitis A is a viral liver disease that can cause mild to severe illness.
* It is spread by faecal-oral (or stool to mouth) transmission when a person ingests food or drink contaminated by an infected person's stool.
* The disease is closely associated with poor sanitation and a lack of personal hygiene habits, such as hand-washing.
* An estimated 1.4 million cases of hepatitis A occur annually.
* Epidemics can be explosive in growth and cause significant economic losses: 300 000 were affected in one Shanghai outbreak in 1988.
* Improved sanitation and the Hepatitis A vaccine are the most effective ways to combat the disease.
Hepatitis A is a liver infection caused by the hepatitis A virus (HAV). The virus is spread when an uninfected (or unvaccinated) person eats or drinks something contaminated by the stool of an HAV-infected person: this is called faecal-oral transmission. The disease is closely associated with inadequate sanitation and poor personal hygiene. Unlike hepatitis B and C, hepatitis A infection does not cause chronic liver disease and is rarely fatal, but it can cause debilitating symptoms.
Hepatitis A occurs sporadically and in epidemics worldwide, with a tendency for cyclic recurrences. Worldwide, HAV infections account for an estimated 1.4 million cases annually. Epidemics related to contaminated food or water can erupt explosively, such as an epidemic in Shanghai in 1988 that affected about 300 000 people.
The disease can wreak significant economic and social consequences in communities. It can take weeks or months for people recovering from the illness to return to work, school or daily life. The impact on food establishments identified with the virus, and local productivity in general, can be substantial.
Symptoms
The symptoms of hepatitis A range from mild to severe, and can include fever, malaise, loss of appetite, diarrhoea, nausea, abdominal discomfort, dark-colored urine and jaundice (a yellowing of the skin and whites of the eyes). Not everyone who is infected will have all of the symptoms. Adults have signs and symptoms of illness more often than children, and the severity of disease and mortality increases in older age groups. Infected children under six years of age do not usually experience noticeable symptoms, and only 10% develop jaundice. Among older children and adults, infection usually causes more severe symptoms, with jaundice occurring in more than 70% of cases. Most people recover in several weeks - or sometimes months - without complications.
Who is at risk?
Anyone who has not had been infected previously or been vaccinated can contract hepatitis A. People who live in places with poor sanitation are at higher risk. In areas where the virus is widespread, most HAV infections occur during early childhood. Other risk factors for the virus include injecting drugs, living in a household with an infected person, or being a sexual partner of someone with acute HAV infection.
Transmission
HAV is usually spread from person to person when an uninfected person ingests food or beverages that have been contaminated with the stool of a person with the virus. Bloodborne transmission of HAV occurs, but is much less common. Waterborne outbreaks, though infrequent, are usually associated with sewage-contaminated or inadequately treated water. Casual contact among people does not spread the virus.
Treatment
There is no specific treatment for hepatitis A. Recovery from symptoms following infection may be slow and take several weeks or months. Therapy is aimed at maintaining comfort and adequate nutritional balance, including replacement of fluids that are lost from vomiting and diarrhoea.
Prevention
Improved sanitation and Hepatitis A immunization are the most effective ways to combat the disease
Adequate supplies of safe-drinking water and proper disposal of sewage within communities, combined with personal hygiene practices, such as regular hand-washing, reduce the spread of HAV.
Several hepatitis A vaccines are available internationally. All are similar in terms of how well they protect people from the virus and their side-effects. No vaccine is licensed for children younger than one year of age.
