New West Nile virus counts for Ontario show the province has already had the worst year for the illness since 2002.
The weekly report from Public Health Ontario says the province's case count jumped another 36 per cent last week, to 158 confirmed and probable cases as of Sept. 8.
The only year Ontario had more cases was in 2002, the first year West Nile virus cases were reported in Canada. That year there were 394 human cases.
About a third of this year's Ontario cases have occurred in Toronto.
Four other provinces have reported West Nile cases this year: Alberta (five), Saskatchewan (two), Manitoba (29) and Quebec (20).
But so far this year there have been no reported deaths due to the disease in Canada.