This means any confirmed or suspected cases must be reported to the public-health authorities. The first case of HPS was recognized in British Columbia in 1994. Since then, cases have been identified retrospectively with the earliest case dating back to 1989 in Alberta. The geographical distribution of HPS is similar in both Canada and the USA, in that it is the the less densely populated western regions that are most affected. Most of the victims were likely exposed to the Sin Nombre Virus during farming and domestic activities in rural areas.
Infection can occur whenever exposed to deer mouse feces, urine, or saliva.
Below is a chart from the Health Canada website on Hantavirus Pulmonary Syndrome. The chart is depicting potential exposure to hantavirus prior to onset of illness in Canadian cases. The number of cases fluctuates in any given year and this is believed to be attributable to fluctuations in the rodent population. Mice have increased breeding capacity during years with mild winters, resulting in larger populations and increased exposure of humans to hantavirus. Canadian HPS cases have occurred in every month of the year except for March, but there seems to be a larger number of cases occurring in the spring and late fall.