Ontario expands hantavirus testing to 10 asymptomatic contacts from cruise outbreak; low-risk cases may exit isolation if negative

Ontario's Ministry of Health announced expanded testing protocols for contacts of the MV Hondius hantavirus outbreak, reversing earlier guidance against asymptomatic testing. Ten people—three deemed high-risk and seven low-risk—are now being tested despite showing no symptoms. High-risk contacts (two cruise passengers and one individual on the same flight as a deceased case) must remain in strict isolation regardless of test results. Low-risk contacts (air passengers without close proximity exposure) may exit their recommended 45-day isolation if they test negative, though daily public health monitoring will continue. This shift reflects ongoing debate among global health officials about the utility of testing asymptomatic individuals given hantavirus's long incubation period. Canada's chief public health officer previously cautioned that negative tests might create false reassurance and reduce isolation compliance. The cruise ship, with some crew remaining, is en route to the Netherlands. WHO reports 10 confirmed international cases with three deaths.