Hantaviruses are a group of viruses carried by rodents that can cause severe disease in humans.

The World Health Organization (WHO) has confirmed five cases of hantavirus linked to deaths aboard a cruise ship in the Atlantic Ocean.

Another three cases are suspected of being linked to the Andes strain of the hantavirus. The WHO says more cases are possible, but the risk to public health remains low.

Speaking to reporters on Thursday, the UN health agency’s chief, Tedros Adhanom Ghebreyeus said the WHO had been notified by the UK of a cluster of passengers with severe respiratory illness on the Hondius cruise ship, currently sailing from Cape Verde in the Atlantic to the Spanish island of Tenerife.

“While this is a serious incident, WHO assesses the public health risk as low,” Ghebreyeus told reporters.

Eight cases have been reported so far, including three dead, five confirmed and three suspected, he said.

Hantaviruses are a group of viruses carried by rodents that can cause severe disease in people. They usually get infected through contact with infected rodents, their urine, droppings or saliva.

The strain of hantavirus detected on the Dutch-flagged cruise ship is the Andes virus. It has been found in Latin America and is the only hantavirus known to be capable of limited human-to-human transmission.

In previous outbreaks, transmission between people has been associated with long and prolonged contacts among household members, intimate partners and healthcare workers.

The first death on the ship was a man who developed symptoms on April 6 and died five days later. No samples were taken, and hantavirus was not identified because the symptoms were similar to other viruses, the WHO’s chief said. The man’s wife became the second victim. She went ashore in Saint Helena, became symptomatic and died on April 25. Another woman became the third fatality, developing symptoms on April 25 and dying seven days later.

“Given the incubation period of the hantavirus, which can be up to six weeks, it is possible that more cases may be reported.”

Before boarding the ship, the first two victims had travelled in Chile, Argentina and Uruguay on a bird watching trip, which included visits to sites home to rats known to carry hantavirus. Argentine authorities are investigating the couple’s movements. Tedros said Argentina would send 2,500 diagnostic kits to laboratories in five countries.

The WHO informed 12 countries whose nationals disembarked in Saint Helena. They are from Britain, Canada, Denmark, Germany, the Netherlands, New Zealand, Saint Kitts and Nevis, Singapore, Sweden, Switzerland, Turkiye and the United States.