Experts race to draft protocols to contain first ship-borne hantavirus outbreak

LONDON - As the cruise ship hit by a hantavirus outbreak sails towards Tenerife, World Health Organization officials are racing to draw up step-by-step guidance for what should happen next for the nearly 150 passengers when they finally reach land on Sunday.

The hantavirus outbreak – which has killed three people among at least eight suspected or confirmed infections - is the first ever recorded on a cruise ship, so some new protocols are needed.

Half-a-dozen current and former WHO officials and hantavirus experts said the outbreak could be managed by adapting standard public health steps, like isolating sick passengers or those who may have been in contact with them. None of the passengers on the ship now have symptoms, the ship's operator has said.

TIPS FROM ARGENTINA

Officials are also seeking tips from Argentina, where a previous outbreak of the Andes virus, the same strain as on the ship, was snuffed out in 2019.

“If we follow public health measures and the lessons we learned from Argentina ... we can break this chain of transmission. This doesn't need to be a large epidemic,” Abdi Rahman Mahamud, director of the WHO's alert and response coordination department, said.

He said the focus was on isolation for sick people, and monitoring and quarantining for other passengers, subject to national government decisions.

Passengers are being split into high-risk and low-risk contacts based on their interactions with sick travellers, the WHO said. Contact-tracing is also key for any who have left the ship already.

The Andes hantavirus is known to spread through close and prolonged contact, and chiefly when a patient is already symptomatic. That information is based largely on the one outbreak where the Andes virus spread between people in Argentina in 2018-19, in which 34 people were infected and 11 died.

“We essentially learned that once you implement basic measures of social distancing, that are essentially very simple – stay home when you are not feeling well – that diminished the circulation and the outbreak burned out,” said Gustavo Palacios, a professor at Icahn School of Medicine at Mount Sinai, in the United States, who is originally from Argentina and a co-author of a key paper on that outbreak.

He and others have been advising WHO on the outbreak since May 2, he said, adding he hoped more attention would now be paid to the risks of hantaviruses, which can have fatality rates of up to 50%.

SOME PLANS IN PLACE

Some governments are already making plans: the UK government said on Friday morning it would repatriate its citizens on a flight under strict infection control measures, and then passengers would be asked to isolate for 45 days, with testing as required.

Krutika Kuppalli, associate professor of medicine at the University of Texas Southwestern Medical Center in the U.S., who formerly worked on mpox protocols at the WHO, said measures could be taken from previous outbreaks.

“It’s the same principle as for measles, or Ebola. Contact tracing doesn’t change,” she said.

The WHO said late on Thursday it was still finalizing guidelines.

- Jennifer Rigby; Editing by Andrew Heavens/Reuters