Hantavirus: How is the outbreak being contained as passengers return?

So far, three people have died, with several others taken ill, after a hantavirus outbreak aboard the cruise ship MV Hondius. Hantavirus is a rare rodent-borne illness that has multiple strains of varying severity.

With the ship now docked, passengers are being returned to their countries of residence. Each will face a slightly different process over the coming days and weeks, depending on their infection status and their country's reactions to such outbreaks.

A Dutch couple, who were the first to become ill and later died, had been visiting South America before departing on the ship from Argentina'ssouthernmost town, Ushuaia, in late March.

Argentina's Ministry of Health are investigating whether the couple were infected by exposure to rodent droppings during a bird-watching tour at a landfill site in the town. The World Health Organization (WHO) have confirmed two of the deaths were from the virus, with the other "probable" at this stage.

What happened on the MV Hondius cruise ship?

Hantaviruses are relatively well known, if rare, and are mostly transmitted from rodents to humans. The symptoms are respiratory and those strains which can develop into 'hantavirus cardiopulmonary syndrome (HCPS)' can have a "fatality ratio, reaching 40-50%" according to the WHO. Severity varies by region too. In Europe, strains generally cause milder illness and a fatality rate between one and 15%, with cases in North and South America often above 30%.

Those on the ship contracted the Andes strain. This is thought to be the only one capable of limited human-to-human transmission, and can cause HCPS. Close, prolonged contact, such as the conditions found on a cruise ship, is usually required to transmit the virus in this way. But the WHO and scientific community have been quick to say this is not comparable to COVID-19.

"The Andes virus requires much, much closer, sustained contact between people, as we understand it," Ann Rimoin, a professor of Epidemiology at the UCLA Fielding School of Public Health in theUnited States, told DW.

"I understand people have a lot of anxiety, having experienced the [COVID-19] pandemic, but this is a very different virus and a different set of circumstances," she added.

An incubation period of six to eight weeks, during which symptoms may not be apparent, meant that illness on the MV Hondius took some time to present itself. According to the WHO, there were 147 people on board, seven of whom are confirmed cases and two probable. Meanwhile, the European Centre for Disease Prevention and Control (ECDPD), a  European Unionmedical authority, says tracing passengers' movements before and after boarding the ship is critical to preventing the virus from spreading.

What happens to the passengers on MV Hondius?

The cruise ship docked in Tenerife over the weekend. Because most people who were on board are yet to test positive or show symptoms, the majority of passengers are either returning to their countries of residence or are already there. Those with symptoms are in various hospitals in South Africa, the Netherlands and Switzerland. A German woman who was a suspected case has tested negative.

Spain flies passengers home from hantavirus-hit ship

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Four other German nationals landed in Frankfurt on Monday, with asymptomatic patients being sent either to hospital or into self-isolation after medical checks, depending on circumstances.

14 Spanish nationals flew to Madrid on Sunday and will be isolated at a hospital in the capital. Turkish, Belgian, Greek, British and Argentinian passengers are traveling to medical facilities after socially-distant flights on Sunday. The last evacuation flight was expected to leave for the Netherlands on Monday afternoon.

Five French nationals, who had been aboard the Hondius, will be placed in "strict isolation until further notice" after one developed symptoms on the plane home, Prime Minister Sebastian Lecornu said. One of the 17 American passengers returned a "weak positive" test in Cape Verde, according to the US Department of Health and Human Services, who will do further tests. 

What is the plan to stop the spread of Hantavirus?

The WHO recommends that "high-risk contacts" of confirmed cases quarantine for "42 days following last exposure." Those who had less contact with an ill patient should only "undertake passive self-monitoring and seek medical evaluation if symptoms occur."

While countries will generally follow such guidelines, isolation circumstances are specific to each person. Those in good health and without symptoms may be sent home to isolate after medical checks, while others will be kept under supervision for longer. Infectious diseases expert Rimoin told DW that as with any virus, keeping tabs on the movement of people and their interactions is important.

"We're talking about multiple jurisdictions, multiple organizations, people having traveled globally, so international coordination and collaboration is going to be key to get all the information, understand it and prevent cases like this from happening in the future," she said.

How have past hantavirus outbreaks been handled?

The most notable recent outbreak of the Andes strain was in Argentina, in 2018-19. Three people who came into contact with infected rodents spread hantavirus to 34 others. In total, 11 people died.

Contact tracing and isolation were established relatively quickly after the discovery of the virus, with the first transmission traced to a birthday party.

Kai Kupferschmidt, a molecular biologist and science journalist, told DW that while transmission in social events may remind the world of COVID-19, the hantavirus poses no such threat and could serve as a useful test case.

"It was interesting to see that there were problems getting the boat to dock anywhere and for countries to work together. But overall, so far, I'm quite relieved that the science does seem to be winning out in terms of how people are responding," Kupferschmidt said. 

How the MV Hondius hantavirus outbreak is tracked worldwide

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Edited by Cai Nebe