Hepatitis A is a liver infection caused by a virus that thrives in the stool of infected humans and animals (mostly primates).
Hepatits A is characterized by fever, fatigue, headaches, and a loss of appetite, often accompanied by jaundice (icterus), vomiting, and diarrhea. A large proportion of infected people experience only a mild feeling of malaise with nonspecific symptoms. The classic clinical syndrome has an abrupt onset of symptoms. The incubation period lasts 15 to 50 days (25 to 30 days on average). In most patients, complete remission occurs within 2 to 4 weeks. The mortality rate of hepatitis A is 0.6 percent.
Hepatitis A is acquired by direct person-to-person contact or by ingesting contaminated water (or ice), seafood from contaminated waters, or raw fruits or vegetables contaminated during handling. Infected individuals are contagious 2 to 3 weeks before symptoms appear until a week after jaundice has developed. The disease confers permanent immunity.
In many parts of the world, there are communities with high rates of hepatitis A. People who travel to rural areas or places where sanitary conditions are inadequate are at substantial risk of acquiring the disease. The following preventive measures should be followed to avoid getting infected:
- Wash hands before handling food;
- Wash hands before meals and after using the bathroom;
- Do not eat or drink beverages and foods that might be contaminated.
Exposing the hepatitis A virus to temperatures of at least 85 degree Celsius for 1 minute will inactivate it. The virus can also be inactivated by adding chlorine or iodine to the contaminated water.
Since the incidence of hepatitis A is common among travellers and the vaccine is safe, it is recommended that all travellers visiting countries where hepatitis A is rated endemic at a high or intermediate level should be vaccinated. In some countries where sanitary conditions are better, immunization is recommended only for travellers who expect to venture outside regular tourist areas. Those who frequently travel abroad or who stay for long periods of time should always be vaccinated.
Vaccines against hepatitis A are administered in 2 shots, at 6 to 36 month intervals. The vaccine confers good immunity within 2 to 4 weeks following the first shot. When 2 doses are administered, the vaccine may be effective up to 20 years.
The hepatitis A vaccine is also available in combination with a hepatitis B vaccine (Twinrix™). The combined vaccine is recommended in the presence of hepatitis C, when no hepatitis B antibodies have been found. Immune globulins may also be administered. They confer immediate immunity lasting about 5 months. However, they are being gradually replaced by the vaccines.
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