Hepatitis A, caused by hepatitis A virus, is an acute infectious disease of the liver that is transmitted person to person by ingestion of contaminated food or water or through direct contact with an infectious person. Millions of people are believed to become infected with HAV every year. The incubation period is two to six weeks and on average is 28 days.
In less developed countries the HAV is usually contracted in early childhood. Clean water helps to decrease contraction of HAV. In 90% of patients no symptoms are even shown. In developed countries such as Europe and the United States most contractions happen to young adults who travel to countries with high incidence of the disease.
The infection produces a self-limited disease that doesn’t result in chronic infection or chronic liver disease. 10 to 15 percent of patients might experience a relapse of symptoms during the 6 months after acute illness. Liver failure is rare and is usually related to age. The body’s response is to produce lifelong antibodies that confer protection against re-infection. The disease has a vaccine and it has been proven to be effective in controlling outbreaks worldwide.
Early symptoms are similar to influenza or in some cases there are no symptoms. Other symptoms can include fatigue, fever, abdominal pain, nausea, appetite loss, jaundice, and clay-colored feces.
HAV enters the bloodstream through the epithelium of the oropharynx or intestine. The blood then takes the virus to the liver where it multiplies. Virions are then secreted into bile and stool. Specific diagnosis is made by the detection of HAV-specific IgM antibodies in the blood. Presence of these antibodies means the acute stage of the illness is past and the person is now immune. The vaccine was first phased in 1996 for children in high-risk areas and was spread to areas with elevating levels of infection. The vaccine is given by injection and a second booster dose is given six to twelve months later.
Although there is a vaccine there is no specific treatment for HAV. Patients are advised to rest, avoid fatty foods and alcohol, eat a well-balanced diet, and stay hydrated. In 1991 the mortality rate in the United States for HAV is 4 deaths per 1000 cases for the general population. In 1997 30,000 cases of Hep A were reported to the CDC in the U.S. In late 2003 an outbreak in north-eastern Ohio afflicted at least 640 people.