Hepatitis A is an acute infection of the liver caused by the hepatitis A virus, a small, non-enveloped virus of the hepatovirus genus.

Hepatitis A is common in developing countries with poor sanitation and hygiene practices. In these countries, most children have been infected with the hepatitis A virus before the age of ten, predominantly without symptoms. In countries where good sanitation and hygiene conditions exist, infection rates are very low.

Contaminated water/food/infected persons

The hepatitis A virus can be transmitted via contaminated water, food and through close contact with an infected person - e.g. sexual contact, especially in men who have sex with men (MSM). Transmission occurs mainly by fecal-oral or smear infection: pathogens excreted in stool enter the oral cavity, e.g., through contaminated hands or food. Hepatitis A is highly contagious.

Hepatitis A disease is often asymptomatic or mild, especially in children under five years of age. In adults, the disease usually begins abruptly and manifests as fever, malaise and abdominal discomfort. Jaundice, in which the conjunctiva (eyes) and skin turn yellow, is a common symptom. Symptoms may last one to two weeks. In 15% of cases, there is a longer-lasting, relapsing hepatitis that can last up to a year. There is no known chronic infection.

Almost all people recover completely from hepatitis A and have lifelong immunity.

There is no specific treatment, patients usually recover on their own

Highly effective hepatitis A vaccination is available and can be used from 1 year of age

Most Austrian hepatitis A cases originate from travel or other stays abroad. In recent years, there has been an increase in hepatitis A cases due to consumption of contaminated food/food in Austria itself.

Ministry of Health: Annual reports of notifiable infectious diseases

Infection: The highest infectivity occurs around the second half of the incubation period, i.e. while the infected person is still asymptomatic. Most patients are considered noninfectious after the first week of jaundice.

Diagnosis

Specific diagnosis is made by detection of HAV-specific antibodies in the blood. The detection of anti-HAV IgM in serum serves, as evidence of a fresh HAV infection together with corresponding symptomatology. Anti-HAV IgM can be detected as early as the onset of symptoms up to three to four months after infection. Short-term detection of anti-HAV IgM is also possible after hepatitis A vaccination.

At the onset of symptoms, anti-HAV IgG is also usually positive. If anti-HAV IgG is detectable after an already completed infection, this represents lifelong immunity.

Other tests include reverse transcriptase-polymerase chain reaction (RT-PCR) to detect hepatitis A virus RNA or genome sequencing to clarify outbreaks. Detection of HAV RNA by nucleic acid amplification technique (NAT, e.g., using PCR) in stool or blood demonstrates fresh HAV infection. To clarify chains of infection in outbreaks, sequencing of the HAV genome must be performed in specialized laboratories.

In the urine of hepatitis A sufferers, there is usually a marked increase in transaminases, direct and indirect bilirubin in the serum, and urobilinogen.