Hantavirus shows no sign of mutating to become more contagious

The respiratory virus that caused a deadly outbreak on a cruise ship is showing no sign of mutating to become more contagious, even though more cases among former passengers may arise in coming weeks, said experts from the European Center for Disease Prevention and Control.

The hantavirus’s genome has been sequenced and it’s similar to the one that caused outbreaks in South America in the past, said Andreas Hoefer, the center’s expert on microbiology and molecular epidemiology. That’s likely where the first passenger was infected before getting on the Hondius expedition vessel and spreading the pathogen, according to the EU’s public health agency.

“At the moment there is no data to suggest this virus is behaving any differently in transmissibility or severity,” Hoefer said Wednesday at a briefing. “All sequences to date are virtually identical.”

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Passengers were repatriated to their home countries earlier this week under a patchwork of measures that reflect uncertainty over how the Andes strain of hantavirus spreads. Health officials stress that the risk to the broader public remains low, but exactly how contagious the virus is and whether people are infectious before developing symptoms remains unclear.

An ECDC expert who joined the ship in Cape Verde found that distancing and other precautions were already in place on board but that passengers had had the kind of “close, prolonged contact” that could lead to infection, said Gianfranco Spiteri, who heads the agency’s global epidemic intelligence and health security operations.

Asked whether patients might be contagious before they develop symptoms, Spiteri said the virus could be found in the blood of patients two days earlier. That means “there might be some risk” of an earlier transmission, he said, leading the agency to recommend that contact tracing include people who were exposed to an infected person two days before their symptoms began.

The ECDC, along with the World Health Organization, is working to trace contacts and monitor passengers across many countries as they assess how the virus spread on board and whether additional infections occur.

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Italy on Wednesday said that a 25-year-old man who was placed in isolation had tested negative for hantavirus, easing concerns about transmission on a flight that briefly hosted an infected Dutch woman.

A former Hondius passenger in France is still in intensive care. She has been receiving life support using an artificial lung, a procedure known as extracorporeal membrane oxygenation, according to Xavier Lescure, an infectious-disease doctor at Bichat hospital, where she is being treated.

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