The World Health Organization said Friday it is embarking on a plan to coordinate studies in more than 20 countries to “better understand the natural history of the disease” following an outbreak of the Andes strain of the hantavirus linked to the cruise ship MV Hondius. 

While stressing that the risks to the public remain low, officials also warned that more infections could still emerge during a six-week long incubation period.

Speaking at a press briefing, WHO Director-General Tedros Adhanom Ghebreyesus said the agency’s “current priorities are to continue to better understand the epidemiology of the Andes virus, including how this outbreak began and spread,” adding that WHO is “working with more than 20 countries to coordinate studies to better understand the natural history of the disease.”

More needs to be understood about potential human-to-human modes of transmission of this particular species of hantavirus, he and other WHO officials at the briefing acknowledged. While hantavirus is usually transmitted by rodents, the Andes species can be transmitted between people. But key questions remain regarding modes of virus transmission and the length of time that an infected person could remain infectious to others, even after testing negative for the virus. 

So far, the outbreak aboard the ship that emerged as it traveled to Antartica and then across the Atlantic, seems to have been contained, Tedros said, noting that “The response to the Hantavirus outbreak is a recent prime example of what can happen when the world comes together to confront a disease threat.”

Ten cases to date – but more could emerge during six-week incubation

As of Friday, a total of 10 cases, including three deaths, have been reported to WHO,  including “eight people who were laboratory-confirmed for Ande’s virus infection, and two probable,” the Director Genera reported

The operation to repatriate the ship’s remaining passengers who disembarked Monday at the port of Tenerife, in the Canary Islands, has been completed, with “more than 120 people now being cared for – all in their home countries or quarantined in host countries en route to their final destination.” 

Some 26 crew members and captain are still on board, but “there are no symptomatic persons on board as of today” Tedros observed. The ship is sailing to the Netherlands where the crew is due to disembark on Monday. 

More cases may be still reported in coming days as passengers are quarantined and tested in specialized facilities or at home, Tedros warned, but he added, “This does not mean the outbreak is expanding. It shows that the control measures are working, that laboratory testing is ongoing, and that people are being cared for with support from their governments.”

He and other WHO officials at the briefing stressed that the risk from this outbreak to the global population is low, even as investigations continue into possible human-to-human transmission aboard the vessel as well as prior to its early April departure from the port of Ushuaia, Argentina, on what was supposed to be a routine a sightseeing cruise hopping from Antartic glaciers to a string of tropical islands off the coast of West Africa.

Outbreak likely began with infection before the ship left Argentinian port

Maria Van Kerkhove, WHO Director for Epidemic and Pandemic Management, said there was “some evidence” of human-to-human transmission in the closed confines of the ship  “particularly between a husband and wife, between the ship’s doctor and a patient.”

She said WHO’s “working hypothesis is that the outbreak began with infection prior to the disembarkment of the ship.”

Van Kerkhove said all passengers and crew were being treated as “high risk” contacts because “we simply don’t have all of the answers yet.” WHO has recommended 42-day quarantines for everyone aboard the ship because “people could be infected and not know it.”

She also confirmed that the third death linked to the outbreak was “an older woman who did die on board on the second of May,” and that testing in the Netherlands later confirmed she was positive for the virus.

Genome sequences of the virus from infected patients have been analyzed in labs in South Africa, Institut Pasteur in Dakar, Senegal and at the Geneva University Hospital, Van Kerkhove said, adding that the United States Centres for Disease Control and Transmission (CDC) has also been involved. None have identified significant mutations in the virus of the sort that occurred in the SARS virus, kicking off the COVID pandemic: 

“I am not a virologist, but what they are telling me is, and what they have said is, that they haven’t identified any changes to suggest a change in the virus to make it more transmissible, more severe, or anything like that,” Van Kerkhove said.

“But what we do hope, actually, is to have more samples coming from rodents, so that we can look at the sequences within the rodents themselves, and do a deeper analysis understanding the circulation of this virus, particularly in South America, disentangle  how circulation happens, and how we can prevent spillover and outbreaks from happening in the future.” 

No WHO hantavirus emergency committee so far

Since the outbreak has so far been contained, and no dangerous virus mutation has been identified, WHO has not called for an emergency meeting of hantavirus experts, said Abdirahman Mahamud, Director Health Emergency Response Operations. Convening an emergency committee would be a required step to any WHO declaration of a global public health emergency, 

“We will do regular updates and risk assessments, should something change, should the DG need to trigger the mechanisms that he has to convene an emergency committee,” Van Kerkhove added. 

Even so, two noted global experts, Ellen Johnson Sirleaf and Helen Clark, co-chairs of The Independent Panel for Pandemic Preparedness and Response, which in 2021 evaluated the global response to COVID-19, last week called for review of how the outbreak had been handled in its preliminary stages aboard the ship.

“A review should determine whether a more precautionary approach could have been applied pursuant to the guidelines in the WHO Handbook for Managing Public Health Events on Board Ships,” said the two women in a statement, adding that the hantavirus outbreak has “tested the international system” demonstrating both its strengths and gaps. 

New Ebola virus outbreak in the Democratic Republic of Congo

Separately, Tedros announced a new Ebola outbreak in the northeastern Ituri province of Democratic Republic of the Congo, with 13 confirmed cases so far. It is the country’s 17th recorded Ebola outbreak since 1976.

Tedros said WHO had released $500,000 from WHO contingency fund for emergencies to immediately support the response,” including “risk communication and community engagement, strengthening disease surveillance, active case finding and contact tracing.”

WHO Africa Regional Director Mohamed Yakub Janabi said the outbreak area was “a very densely populated area” with “population movement linked to mining and cross-border trade,” which “naturally increases the transmission rate.”

WHO officials said they were still awaiting confirmation of the Ebola strain but noted that vaccine protocols and emergency response systems were already being prepared.

See related hantavirus coverage here:

https://healthpolicy-watch.news/review-of-global-outbreak-response-as-all-passengers-leave-hantavirus-hit-ship/

Image Credits: Franklin Braeckman/Oceanwide Expeditions , BBC, El Pais/OpenStreetMap.