What You Need to Know

Last week, the European Centre for Disease Prevention and Control (ECDC) issued an alert warning of a multicountry outbreak of hepatitis A virus (HAV) infections. Two closely related virus strains have been identified across affected regions, with outbreak spikes centered in Austria, Czechia, Hungary, and Slovakia.

The spread appears to be via ongoing person-to-person transmission within connected social networks or geographical areas, according to genetic sequencing. While Germany is not considered an affected country, it has identified three cases with genomic profiles matching those in Hungary and Austria.

Cross-Border Transmission

The ECDC said testing confirmed cross-border transmission and recommended that EU/European Economic Area public health authorities undertake epidemiologic investigations, targeted prevention measures, and community-based outreach to contain the outbreak and protect public health.

In total, the four countries in the outbreak have reported 2097 cases of hepatitis A since the start of the year: 880 in Slovakia, 87 in Austria, 600 in Czechia, and 530 in Hungary. The disease has proved fatal in three cases in Austria and six in Czechia.

Transmission Routes

The ECDC also issued a rapid risk assessment summarizing that HAV is transmitted primarily via contaminated food, water, or close contact with infected individuals. Risk factors include poor sanitation, lack of access to safe water, inadequate access to basic hygiene, close contact with infected individuals, particularly during risky sexual behaviors such as anogenital-oral sex, use of recreational drugs, and travel to endemic areas. The likelihood of developing symptomatic or severe hepatitis A increases with age and is higher among people who are immunosuppressed or have chronic liver disease.

The current outbreak is primarily affecting homeless adults, people who use or inject drugs, and those living in poor sanitary conditions or with limited access to healthcare. Additionally, cases have been reported among members of the Roma communities in both Czechia and Slovakia.

Age Differences

The strains detected all involved two closely related HAV subgenotype IB variants. However, there are demographic differences between affected populations in different countries. Reported cases in Hungary were mainly in adults, whereas in Czechia the most affected age groups were young children aged 1-9 years and young adults aged 25-44 years.

In Slovakia, where the outbreak has been ongoing since the end of 2022 and case numbers are now falling, cases were reported especially in Roma communities in eastern Slovakia and involved mainly children. However, the current epidemiologic pattern marks a notable shift from previous years, the ECDC said. Although 47% of the 2025 cases have occurred within Roma communities, an additional 20% involve adults who are homeless and/or use or inject drugs. Several smaller clusters have also been reported in young children attending preschool facilities.

In Austria, case numbers are still increasing — the number reported for the first 5 months of 2025 already exceeds the total recorded in 2024. There was a male predominance (68%), patients’ ages ranged from 3 to 84 years (median of 34 years), 63% of cases for which information was available required hospitalization, and three deaths have been reported.

What Clinicians Should Know

To find out what frontline clinicians might need to know about the hepatitis A outbreak, Medscape Medical News spoke with Kinga Kardics, MD, a tropical disease specialist at the Pediatric Center at Semmelweis University, Budapest, Hungary. She said the center was seeing one to three patients a week with HAV infections.

How Is the Virus Transmitted?

The virus can be transmitted through contaminated water, food, and via the fecal-oral route among close contacts: household members, sexual contacts, and children attending day care centers or schools. Among pediatric patients in Hungary, the main transmission route has been the fecal-oral route in schools and nurseries, she said.

Who Is at Risk?

Kardics noted that additional risk factors or risk groups that have been associated with the illness in outbreaks include men having sex with men, children with immunodeficiencies, pregnant women, and patients with chronic liver diseases.

What Symptoms Should Alert Physicians?

Most patients with HAV infection have few or mild symptoms, Kardics said. Usual signs are fatigue, nausea, loose stools, fever that lasts just for a few days, and jaundice.

Most of the pediatric patients seen at her center have been asymptomatic or had only mild symptoms. In teenagers, the onset of the illness is usually abrupt, with fever, malaise, and abdominal discomfort. Jaundice is the predominant symptom.

What Is the Course of Disease?

Most patients recover spontaneously, are in good condition, and can stay at home until recovery, she said, though some patients need intravenous fluid replacement for dehydration. So far this year, the center at Semmelweis University has hospitalized about 10 children with hepatitis A infection. All of them recovered, no chronic infection has been detected, and no hepatitis A-related death has been reported so far in the pediatric population.

What Basic Hygiene Precautions Should Be Advised in the Community?

Practicing good hand hygiene can prevent the spread of HAV, Kardics said. People in the community should be advised to undertake frequent and thorough handwashing with soap and water, particularly after using the bathroom, after changing diapers, and before preparing or eating food.

What Should People in At-Risk Groups Do to Protect Themselves?

Strict control measures, such as reinforcing personal hygiene, contact tracing, and administration of vaccine to exposed persons, have proven to be effective in outbreaks, Kardics said. Populations with a higher risk for serious disease from HAV infection should consider vaccination. Several inactivated vaccines are available for prevention, all showing very high efficacy. Active (antigen) immunization is also available in Hungary and is effective if administered within 2 weeks of exposure.

Prophylactic Measures

The ECDC has advised that physicians in all countries should consider targeted vaccination of population groups most likely to be exposed to the virus. Post-exposure prophylaxis using the hepatitis A vaccine should be prioritized for close contacts of identified cases according to national guidelines.

Epidemiologic investigation of the outbreak is continuing.