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Germs that infect humans

Hepatitis A

Hepatitis A

© Illustration Bruno Laporte

Microorganism: this virus is an hepatovirus from the Picornaviridae family.

Disease: hepatitis A

Occurrence of the disease

Current situation: this disease has a low mortality rate. In 1998, 1,090 cases were reported in Canada.

Mechanism of action of the microorganism: the virus travels to the intestine where it reproduces.

Symptoms of the disease: the symptoms are usually benign. They include fever, weight loss, nausea, and abdominal discomfort. In the most severe cases, the virus can enter the bloodstream and move to the liver, the kidneys, and the spleen. However, we usually find the virus in the intestine. For this reason, feces are very infectious. Jaundice will develop if the liver is infected. The symptoms last between two and 20 days.

Incubation period: the incubation period is about 28 to 30 days.

Contagious period: the second half of the incubation period is the most contagious period and it continues a few days after the appearance of jaundice when this symptom is present.

Transmission: this disease is transmitted through human feces (oral-fecal transmission). Recent epidemics in the homosexual population, intravenous drug users and handlers of contaminated foods.

It is estimated that 40 to 80% of the population of the United States has natural antibodies against this disease. This means that these people have been unknowingly in contact with the hepatitis A virus.

Hosts: humans

Treatment: no specific treatment exists

Geographical distribution of the microorganism: this disease is present worldwide, but particularly in developing countries.

Prevention: rigorous personal hygiene and an adequate water purification system. There also exists an inactivated hepatitis A vaccine.

Vaccine: an inactivated vaccine is recommended to people travelling to regions where hepatitis A is highly present. A combined hepatitis A and B vaccine is also recommended for homosexuals, intravenous drug users, and patients suffering from liver disease.