The Canadian Cooperative Wildlife Health Centre (CCWHC), supported by Health Canada, carries out Ontario's WNv testing on birds. The purpose of bird surveillance is to establish where WNv is present. This information helps the medical officer of health for each local health unit in their efforts to prevent and control WNv illness.

Species tested are crows, blue jays and ravens (in northern Ontario). The selection of these species is based upon their susceptibility to WNv and the fact that they not infrequently die of the disease, making them available for WNv determination. Public health units begin submitting birds to the CCWHC in the spring. Regional submission start dates are determined by the typical arrival time of birds in each area as established by the experience of the naturalists of the CCWHC.

Once WNv is demonstrated to exist in the bird population within a local health unit, it is assumed that WNv infection exists throughout the bird flocks in that jurisdiction. Further bird testing is therefore no longer deemed necessary and the CCWHC reserves the option to re-allot testing submissions to other areas that have not demonstrated WNv in their bird populations.

WNv bird surveillance is not intended as an ongoing monitoring of the status of bird health with respect to WNv. It is important to note that the absence of positive bird findings after the 'latest' date does not imply that WNv is no longer in the local bird population.

The CCWHC provides the most current data on WNv infections in sentinel birds. Enquiries regarding avian surveillance in Ontario may be directed to the Public Health Branch or to the CCWHC.

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