Frequently asked questions about hantavirus and its spread

12.5.2026 13.08 | Published in English on 13.5.2026 at 15.58

News item

The wider spread of hantavirus-related disease in Europe is unlikely, and the risk to the public is very low. However, a virus outbreak on a cruise ship has raised concern and questions, which THL experts address here.

What are hantaviruses and what diseases do they cause?

There are several types of hantaviruses that cause different illnesses.

In certain parts of South America, Andes virus—a hantavirus—can cause a severe illness primarily affecting the respiratory system, including fever, cough, and in some cases nausea or diarrhea. Human infections have been very rare, but 20–50% of confirmed cases have resulted in death. Andes virus does not occur naturally in Europe.

In Europe, the most common hantavirus is Puumala virus, mainly found in Finland and Sweden, which causes nephropathia epidemica (bank vole fever). This is a self-limiting febrile illness, with over a thousand cases annually in Finland, and fatalities are extremely rare.

How do hantaviruses spread to humans?

Humans can become infected by inhaling particles from urine, droppings, or saliva of infected rodents.

Among hantaviruses, only Andes virus—identified as the cause of the spring 2026 cruise ship cases—can spread from person to person. Even in endemic areas, most infections result from rodent exposure, and human-to-human transmission has been very rare, requiring close and prolonged contact.

Symptoms usually begin about two weeks after exposure but can vary from 1 to 6 weeks.

Each hantavirus is associated with a specific rodent species, and the host species for Andes virus does not exist in Europe.

Does Andes virus cause large outbreaks?

Clusters caused by Andes virus have been small. While the disease can be severe, it does not pose the same epidemic risk as COVID 19, because transmission between people requires close and prolonged contact.

How is Andes virus linked to the cruise ship?

Several individuals on a cruise ship in the Atlantic fell ill in late April–early May 2026 with disease caused by Andes virus. All known cases were aboard the ship.

Current assessment suggests at least one passenger was exposed in South America before boarding and may have transmitted the virus to others.

THL is monitoring the situation with the European Centre for Disease Prevention and Control (ECDC) and the World Health Organization (WHO). Public health authorities are coordinating closely.

Is it possible cases could occur in Finland?

The risk to people in Finland and elsewhere in Europe is considered very low, as transmission requires prolonged close contact. Control measures are also in place.

What is known about exposed Finnish travelers?

Two Finnish travelers may have been exposed on April 25, 2026, on a flight in Johannesburg. THL received the information on May 8 through international channels. After the exposed individuals had been reached, the information was communicated to the public on the same day.

They remain asymptomatic and are under close monitoring. As a precaution, they are currently avoiding contact with people outside their household.

How would a suspected case be handled in Finland?

Healthcare services are well prepared to test and treat suspected cases. Contacts of confirmed cases are traced starting two days before symptom onset.

Testing is based on symptoms, as early testing can produce false negatives.

Andes virus infection is classified as a generally hazardous communicable disease, enabling quarantine and financial compensation.