Ontario now testing 10 asymptomatic people for hantavirus; low-risk cases to stop isolating if negative

Seven more people are being asked to isolate in Ontario, which brings the total number of monitored cases for hantavirus to ten in the province.

TORONTO — Ontario’s ministry of health says it is now testing 10 asymptomatic people with connections to a hantavirus-stricken cruise, a shift from government remarks made earlier this week.

The province says the three “high-risk” travellers — two who were on the cruise and one who was on the same flight as a person who has since died of hantavirus — will stay in strict isolation regardless of their result.

However, a ministry spokesperson says the seven “low-risk” contacts can stop their recommended 45-day isolation if they test negative, while daily public health monitoring will continue.

Public health officials have described “low-risk” contacts as air passengers who were on the same flight as someone with hantavirus, but weren’t in close proximity to them.

The effectiveness of testing asymptomatic people for hantavirus has been raised several times over the past week. Health officials around the world are grappling with this question, given the long incubation period of the virus.

Earlier this week, Sylvia Jones, Ontario’s health minister, said the guidance from the province’s top doctor was that it wasn’t appropriate at the time.

Dr. Joss Reimer, Canada’s chief public health officer, suggested testing asymptomatic people might give a false sense of security.

“If somebody is perhaps testing negative, but later could go on to develop hantavirus, I don’t want that individual to be taking their isolation requirements less seriously. So that’s the balance that we’re trying to strike in getting as much information as we can and is useful without giving people a false reassurance that might lead to unnecessary exposures,” Reimer said.

The World Health Organization says its international hantavirus case count is 10, as the previous tally had an inconclusive test in the U.S. that’s since been confirmed as negative. Three people have died.

• READ ALSO: Travel industry insiders aren’t worried about the future of cruises, even with outbreaks

- With files from Nicole Ireland

This report by The Canadian Press was first published May 15, 2026.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

Hannah Alberga, The Canadian Press