FrequencyOccurrence
Approximately 20% of all viral hepatitis is caused by hepatitis A virus (HAV). About 2000 cases are reported every year; however, since so many hepatitis A sufferers have no or only unspecific symptoms, experts assume that there are about 10,000 or more cases of hepatitis A.
Causes of hepatitis A
The cause of hepatitis A (HA) disease is infection with the hepatitis A virus. The virus is transmitted to humans through the consumption of contaminated food, drinking water contaminated by faeces or objects. The infection cycle is completed by excretion with the viruses via bile and stool and the faecal-oral transmission route.
Transmission and infection routes in hepatitis A
Hepatitis A viruses are usually transmitted faecal-orally and only very rarely via the blood (e.g. through a transfusion). In most cases it is smear infections that carry the virus. Often through contact with stools containing the virus, contaminated drinking water or food and contaminated objects.
More precisely, for humans this means that insufficient hand hygiene, e.g. after going to the toilet, leads to direct transmission of the virus to the oral mucosa. The virus can then enter the digestive tract unhindered. The transmission takes place enteral, which means via the intestinal mucosa.
The digestive tract begins in the oral cavity and ends at the anus. As it passes through the small intestine, the virus is absorbed into the bloodstream. From here it reaches the liver, which is primarily affected and damaged by the hepatitis A virus.
In rare cases, transmission is also possible via the bloodstream if the infection is in the so-called viremia phase. Viremia phase means the presence of the virus in the blood during the infection, usually for a certain period of time. Since a person infected with hepatitis A virus excretes the virus via the stool, the virus is not transmitted via the “classic” kissing.
With adequate hand hygiene, transmission of the virus through kissing is very unlikely. In industrialized countries with a high hygienic standard, such as Germany, infections with the hepatitis A virus are rather rare.Every year, about 30-40 new cases per 100,000 inhabitants occur in the Federal Republic of Germany. From the age of 50 onwards, 50-60% of the population is infected by the hepatitis A virus.
Due to the low infection rate in industrialized countries, some children and adolescents are without natural immunological protection, since no antibodies are formed without infection or vaccination. 50% of all hepatitis A infections in Germany are acquired through vacation stays in the South or Eastern Europe. Hepatitis A infection is one of the so-called tourism diseases, as it is transmitted due to poor hygienic conditions (especially in developing countries) (mainly in Eastern Europe, tropical countries and the Mediterranean area).
Infection occurs above all when the hygienic conditions do not meet the necessary standard. Special caution is required at public toilets and camping sites. The problem is that the hepatitis A virus is very resistant to acids and alkalis and can tolerate high temperatures well.
Not only travelers are particularly at risk, but also medical staff, workers in the restaurant and food industry, workers in refugee camps and residents of psychiatric institutions. Children in their first year of life can excrete the virus for several weeks and thus infect others (especially siblings and parents). Otherwise there is a risk of infection between one to two weeks before the onset of the virus and until one week after the end of the icteric stage.