Where has the deadly hantavirus come from and how does it spread?

Three people suspected of having hantavirus have been evacuated from the MV Hondius cruise ship, following an outbreak that killed three passengers. The evacuees will receive medical care in the Netherlands.

The ship departed Ushuaia, Argentina, on April 1 and followed a route across the South Atlantic, with stops in Antarctica, South Georgia, Nightingale Island, Tristan da Cunha, St. Helena and Ascension Island.

Two people died on board the ship and a third person died in South Africa two days after disembarking on St Helena. A British man who was also on the ship remains in intensive care in Johannesburg, South Africa.

A man in Switzerland who jumped ship in late April also reportedly tested positive for hantavirus after experiencing symptoms. Two Britons who were on the ship but have no symptoms are self-isolating at home, the UK Health Security Agency said.

What is hantavirus?

Hantaviruses are a group of viruses carried by rodents that can cause serious illness in humans. People usually become infected through contact with infected rodents or through their urine, feces, or saliva.

In different parts of the world, there are different hantaviruses associated with different clinical syndromes. In the Americas, hantaviruses can cause a serious respiratory illness known as hantavirus cardiopulmonary syndrome (HCPS), which kills up to 50 percent of those diagnosed. In Europe and Asia, hantaviruses cause hemorrhagic fever with renal syndrome (HFRS), which mainly affects the kidneys and blood vessels.

Worldwide, approximately 10,000 to more than 100,000 infections are estimated to occur each year, with the highest infection rates recorded in Asia and Europe.

According to the South African National Institute for Communicable Diseases, two people who disembarked from the ship tested positive for Andes virus, a form of hantavirus that causes HCPS. This virus is believed to be capable of human-to-human transmission during close, prolonged contact.

What are the symptoms of hantavirus?

Early symptoms often include fever, muscle pain, headache, and gastrointestinal symptoms. Some patients then progress to respiratory disease. The diagnosis is usually made by specialized blood tests.

How is hantavirus spread?

The usual route of infection is exposure to infected rodents, particularly inhalation of viruses from the urine, feces, or saliva of contaminated rodents.

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

Infection can also occur, although less frequently, through rodent bites. Activities that involve contact with rodents, such as cleaning enclosed or poorly ventilated spaces, farming, forestry work, and sleeping in rodent-infested homes, increase the risk of exposure.

According to the WHO, human-to-human transmission has only been documented for Andes virus in the Americas and remains rare. When it occurs, person-to-person transmission is associated with close, prolonged contact, particularly between household members or intimate partners, and most likely occurs during the early phase of the disease, when the virus is more transmissible.

How worrying is this epidemic?

Adam Taylor, of Lancaster University in the UK, says people should not be alarmed. “Hantavirus transmission typically requires contact with animal body products, rather than being transmitted from human to human,” he says. “Precautions are being taken on board to minimize risks, but they are only precautions.”

Hewson says it’s important not to overinterpret cruise ship decor. “The fact that cases were identified in individuals associated with the same vessel does not in itself tell us whether the exposure occurred on the vessel, before boarding, during shore excursions or through other shared environmental exposure,” he said. “This is precisely why public health investigations, laboratory confirmation and, where possible, sequencing of the virus are important. »