Cruise ship hantavirus outbreak declared over by WHO

A hantavirus outbreak linked to a cruise ship has been contained and no longer poses a public health risk, according to the World Health Organization (WHO). Thirteen people were infected and three died.

The outbreak was linked to the M/V Hondius, a Netherlands-flagged cruise ship, after WHO was notified on May 2 of a cluster of severe acute respiratory illness on board. All confirmed cases were among people who had traveled on the ship.

As of Thursday, 13 cases had been reported globally, including 12 laboratory-confirmed infections with Andes hantavirus and one probable case. Three of the patients died, giving the outbreak a case fatality rate of 23%.

Ten of the patients were hospitalized. WHO said eight have recovered and been discharged, while two remain hospitalized, one in South Africa and one in France.

The outbreak included nine male patients and four female patients. The median age was 65, and the three patients who died were 69, 70 and 79 years old.

WHO said Thursday that all identified contacts have completed a 42-day follow-up period without any additional secondary cases, confirming that transmission has been interrupted. The agency said no further related transmission is expected.

Health authorities identified and monitored contacts in 33 countries and overseas territories, including passengers and crew, contacts linked to a case in Tristan da Cunha, people on two international flights, health care workers and airport crew.

A total of 317 high-risk contacts completed quarantine and monitoring, while 336 low-risk contacts completed self-monitoring.

The exact source of the outbreak has not been determined. WHO said currently available information suggests the first infections were likely acquired on land before embarkation, followed by limited human-to-human transmission aboard the ship.

Andes hantavirus is endemic in parts of South America and is usually linked to exposure to infected rodents or contaminated surfaces. Unlike most hantaviruses, Andes virus can sometimes spread between people, but WHO said such transmission remains limited and typically requires close and prolonged exposure.

WHO said the confined setting of the cruise ship likely helped the virus spread during the voyage, but there was no evidence of sustained transmission or transmission dynamics similar to highly contagious airborne diseases such as measles.

Investigations are continuing to determine the source and circumstances of the outbreak, including genomic sequencing of Andes virus samples from surveillance cases in Chile and Argentina.