09/19/2012 03:02 EDT | Updated 11/19/2012 05:12 EST

The rise in West Nile virus cases in Ontario appears to be slowing

TORONTO - New West Nile virus figures for Ontario suggest this season's outbreak may be beginning to slow down.

The figures, compiled by Public Health Ontario, show cases increased by just under 20 per cent last week.

The week before cases rose by 36 per cent, and the week before that they jumped by 41 per cent.

Ontario remains far ahead of other provinces this year in terms of West Nile cases.

Quebec has reported 39 cases, Manitoba has recorded 33, Alberta has had seven and Saskatchewan has found six.

To date this year Ontario has had 189 confirmed and probable cases, more than any other year except 2002, which is the worst year on record for the province.

In 2002 there were 394 human cases in Ontario. It was the first year the West Nile virus triggered human disease in Canada.

Cases in the United States — which is having its worst West Nile year ever — are still on the rise. The U.S. Centers for Disease Control are reporting 3,142 cases in total so far this year, 1,630 of them involving the severe form of the disease.

The U.S. has also reported 429 West Nile virus deaths so far in 2012. To date there have been no reported deaths in Canada in 2012.

Manitoba health department suggests the risk of infection in that province has fallen substantially, but isn't yet nil.

"There will continue to be a minimal level of risk until the weather becomes colder or we have our first hard frost," the department says on its website.

This week's Ontario report shows that the highest risk of getting infected with West Nile virus this year has been in Windsor-Essex County, where there have been nearly five cases for every 100,000 people in the region.

Halton Region — an area west of Toronto that includes the cities of Oakville and Burlington — has the second highest rate for the province, 3.55 cases per 100,000 people.

Other high risk parts of the province this year have been: Toronto, with a case rate of 2.87 per 100,000; Hamilton, with 2.81 cases per 100,000; and Haldimand-Norfolk, north of Lake Erie, with a rate of 2.71 cases per 100,000.