Health authorities across Europe are closely monitoring a growing hantavirus outbreak linked to the expedition cruise ship MV Hondius after another passenger reportedly became ill following a trip to South America.

The latest case involves a man from Switzerland who sought medical attention at a hospital in Zurich after learning about the outbreak from the cruise operator. According to reports, he had recently returned from South America with his wife before developing symptoms associated with the virus.

Doctors at the University Hospital Zurich placed the passenger in isolation as a precautionary measure. His wife is also self-isolating, although she has not shown any signs of illness so far

Swiss public health officials have reassured residents that the overall danger to the public remains low. However, authorities are continuing contact tracing efforts to identify anyone who may have been exposed.

The outbreak has attracted worldwide attention after several serious cases were reported among passengers connected to the vessel. The World Health Organization (WHO) confirmed that multiple people linked to the cruise became infected, with at least three deaths reported so far.

Health experts suspect the outbreak may involve the Andes strain of hantavirus — a rare form capable of spreading between humans through close contact. This version of the virus is considered particularly dangerous because of its high fatality rate, which can reach up to 40 percent in severe cases affecting the lungs and heart.

The WHO is now working with several countries to trace passengers and crew members who may have had contact with infected travelers. More than 80 passengers and several crew members are reportedly being monitored after sharing a flight with a Dutch passenger who later died after testing positive for the virus.

Meanwhile, the MV Hondius remains at sea with around 150 passengers onboard after multiple ports reportedly declined permission for the ship to dock.

Medical teams have already evacuated several suspected cases from the cruise ship for treatment in the Netherlands, while international health agencies continue to assess the situation.

Experts say the outbreak has caused concern because hantavirus infections can remain undetected for weeks before symptoms appear. Unlike many other strains, the Andes variant can occasionally spread between people, although specialists stress that transmission is extremely uncommon.

Professor Sir Andrew Pollard of the Oxford Vaccine Group explained that person-to-person spread generally occurs only through close contact with someone who is already showing symptoms. He added that the situation is very different from viruses such as Covid-19, which spread easily even before symptoms develop.

According to health authorities, the risk of wider community transmission remains very low because infected individuals can be isolated quickly once symptoms appear.

Hantaviruses are usually carried by rodents and are commonly spread through exposure to contaminated urine, droppings, or saliva. The infection can lead to two severe illnesses: hantavirus cardiopulmonary syndrome (HCPS), which attacks the lungs, and hemorrhagic fever with renal syndrome (HFRS), which affects the kidneys.

Early warning signs may include fever, muscle pain, fatigue, headaches, dizziness, nausea, and stomach problems. In more serious cases, patients can develop breathing difficulties, chest tightness, low blood pressure, internal bleeding, or kidney failure.

International health agencies continue to monitor the outbreak, while passengers and crew on the cruise undergo further medical observation.