Hantavirus: Where has the deadly cruise ship outbreak come from?

An outbreak of hantavirus has been reported on a ship anchored off Cape Verde in the Atlantic Ocean, posing a significant health risk with a mortality rate that can reach up to 50 percent in humans.

The Dutch-flagged cruise ship, MV Hondius, has seen seven infections, resulting in three fatalities.

What is hantavirus?

Hantaviruses are a group of viruses that are primarily carried by rodents and can lead to serious illnesses in humans. Infection typically occurs through contact with infected rodents or their bodily excretions like urine, droppings, or saliva.

The clinical manifestations of hantavirus vary across regions. In the Americas, it can cause hantavirus cardiopulmonary syndrome (HCPS), a severe respiratory illness with a fatality rate of up to 50 percent. In Europe and Asia, it causes haemorrhagic fever with renal syndrome (HFRS), which affects kidney function and blood vessels.

Globally, there are estimated to be between 10,000 and over 100,000 cases annually, predominantly in Asia and Europe.

The specific strain affecting those on board the ship has yet to be identified. “There are multiple different species, with at least 24 that cause disease in humans, and until we know which is involved in these circumstances on board the ship, we can’t really say anything about what is going on that is baffling or surprising,” says Adam Taylor from Lancaster University in the UK.

Where has the ship been?

The World Health Organization (WHO) reported being informed on 2 May about a series of severe acute respiratory illnesses, which included two deaths and one critically ill passenger, on the MV Hondius.

The WHO stated that the ship left Ushuaia, Argentina, on 1 April 2026, with a route through the South Atlantic, visiting places like Antarctica, South Georgia, Nightingale Island, Tristan da Cunha, Saint Helena, and Ascension Island.

The stopover in Argentina is under scrutiny in the investigation of the outbreak, as the Andes virus, a type of hantavirus found in South America, can be transmitted between humans through close and prolonged contact, according to the WHO.

The WHO reported that there were 147 people on board, comprising 88 passengers and 59 crew members from 23 different countries. It noted that the level of interaction with local wildlife during the trip, or before boarding in Ushuaia, has yet to be clarified.

What are the symptoms of hantavirus?

Initial symptoms often include fever, muscle aches, headaches, and digestive issues, with some progressing to respiratory problems. Diagnosis typically relies on specialized blood tests.

How is hantavirus spread?

The virus is mainly spread through exposure to infected rodents, especially by inhaling particles from contaminated urine, droppings, or saliva.

“This is why investigations of suspected cases often focus on whether people may have had exposure to rodent-contaminated environments, food stores, cabins, storage areas or other enclosed spaces. Hantavirus is not generally considered easily transmissible between people,” said Roger Hewson from the London School of Hygiene & Tropical Medicine in a statement.

Although less common, infection can also occur through rodent bites. Activities such as cleaning poorly ventilated areas, farming, forestry, and staying in rodent-infested places increase the risk of exposure.

The WHO indicates that human-to-human transmission has only been recorded in the Americas with the Andes virus, and it is rare. When it occurs, it usually involves close and prolonged contact, typically among family members or close partners, and is most likely in the early stages of illness when the virus is more easily spread.

How worrying is this outbreak?

Taylor emphasizes that there is no cause for alarm. “Hantavirus transmission typically requires contact with animal bodily products to transmit, rather than human to human,” he says. “Precautions are being taken on board to minimise risk, but these are just precautions.”

Hewson urges caution in interpreting the cruise ship context. “The fact that cases have been identified in people associated with the same vessel does not by itself tell us whether exposure occurred on the ship, before boarding, during shore excursions, or through some other shared environmental exposure,” he said. “That is precisely why public health investigations, laboratory confirmation and where possible, virus sequencing are important.”