West Nile Virus
West Nile Virus Surveillance Results
Results are tabulated from weekly tests of mosquito traps and suspected and confirmed cases of West Nile Virus in horses and people.
2013 West Nile Virus Surveillance Results
Cumulative total is the total since testing began this season.
Human Cases of West Nile Virus
During West Nile Virus (WNV) season, it is important to provide risk information to the public as soon as possible so that the public can be more aware about ongoing disease occurrence in the province and take precautions to reduce mosquito exposure during outdoor activities.
The Saskatchewan West Nile Virus risk index is primarily based on a composite of heat degree days and mosquito trap results including speciation and positive viral pools. Positive horse cases and positive human cases may provide further insight; however by the time humans develop symptoms, usually the risk has peaked.
Only about 20 percent of people infected with WNV will develop mild symptoms, and less than one percent (one in 150) will develop severe symptoms such as high fever, convulsions, numbness and/or paralysis, according to the Centre for Disease Control in the United States. The risk of severe symptoms such as neuroinvasive disease has been associated with the individual's underlying health conditions such as a weakened immune system and/or chronic diseases.
Table 1 shows the number of specimens submitted by physicians across the province that produced positive lab test results, indicating suspected human cases of WNV. Some of these positive tests may be false positive or infections from the previous year. This table shows how many patient specimens were positive for the WNV initial test by eco-region on a weekly basis.
*Table 1. 2013 Positive Lab Tests* for Suspected West Nile Virus - Human Infections in Saskatchewan
*Includes positive lab tests plus any updates from the follow up tests on discrete clients after the first confirmed WNV human infection. Revised numbers from previous weeks' results reflect the removal of false positives.
Table 2 indicates the number of reported West Nile Neurological Syndrome (WNNS), hospitalized severe West Nile Non-Neurological Syndrome (WN Non-NS) and Asymptomatic Blood Donors. The table is updated as more information becomes available. These categories align with national surveillance categories.
* One death is reported in which WNV may have had a contributing cause.
† Human cases can also be identified when blood donor screening tests indicate infection in a healthy person referred as an asymptomatic infection. These individuals are notified that they have been infected with WNV, and are advised to consult a health professional if they experience symptoms or are concerned.
About the WNV Human Surveillance System
Saskatchewan's public health surveillance system is not designed to detect infected people who display no symptoms or who have mild symptoms that do not require medical attention. Severe cases, such as individuals with neurological disease or with symptoms serious enough to be hospitalized, are likely to be tested for WNV and reported to public health.
When health care providers identify a patient with possible severe West Nile virus symptoms, blood samples are sent to the Saskatchewan Disease Control Laboratory for testing. Positive results are reported as suspected cases, and when subsequent testing and diagnosis confirms a serious case, they are reported to the province's Chief Medical Health Officer. These numbers are reported to the public.
If an individual has symptoms that require medical attention and hospitalization, it may take from a few days to several weeks for all their test results to become available. New cases that are reported typically result from WNV infected mosquito exposure/bite that occurred in the current or previous season.
During extended periods of warm weather, take personal protective precautions against mosquitoes in both urban and rural areas.
For estimated West Nile Virus risk levels in Saskatchewan, see Related Links, below.
Weekly risk ratings for contracting West Nile Virus in Saskatchewan, updated during warm weather risk periods.
Click on your health region, or see the list of communities to determine your health region.
Weekly reports describing some details of factors affecting the potential for infection with West Nile Virus, and tracking human cases and other signs indicating risk.
Information about the disease, prevention, mosquito control programs, risk levels and surveillance results.