Manitoba Health

¹ The West Nile virus dead corvid pick up program is not in effect in 2007. Dead corvids are no longer needed as an early indicator of West Nile virus in Manitoba or to determine geographic distribution. Larval sampling, mosquito sampling and testing in addition to other factors (temperature, etc.) will be used to guide the assessment of risk of West Nile virus exposure.

² Other animals and birds that have tested positive for WNV in 2007 include: one blue jay, one magpie, one seagull, and one snowy owl.

³ Updated in 2005 after receiving a late report on a Manitoba resident with WNV who was investigated in Saskatchewan in 2003.

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Culex tarsalis Mosquito Trap Catch by Regional Health Authority 2007*

* As of January 17, 2008.
(Routine mosquito trapping was discontinued the week ending September 22, 2007.)

Permanent mosquito traps are set up in 37 community areas in southern Manitoba to monitor Culex tarsalis mosquitoes, the mosquitoes that are most likely to transmit West Nile virus to humans in Manitoba. The above table will represent the average number of Culex tarsalis mosquitoes per trap catch for the week by Regional Health Authority (RHA) and  provides a relative measure of the activity levels of Culex tarsalis from one RHA to another and over time. This measure is an indicator as to whether Culex tarsalis mosquito populations are rising or falling or staying steady. It should be noted that these RHA averages provide an approximate indication of the number of Culex tarsalis in the RHA, counts in specific locations within the RHA will vary depending on local conditions, temperature, precipitation, etc.

Note:  Normally, two Centers for Disease Control (CDC) mosquito traps baited with carbon dioxide are run for two nights each week in each Manitoba community except Winnipeg and Brandon (where proportionately more traps are used because of larger community size). 

The average number of Culex tarsalis per trap catch (a trap catch – may also be called a “collection”- represents the mosquitoes collected by one trap during one night from approximately one hour before sunset until approximately one hour after sunrise) is calculated by dividing the total number of Culex tarsalis collected for the whole week in a given RHA by the number of collections.

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Positive Mosquito Collections (Adult) by RHA 2007

* As of January 17, 2008.
(Routine mosquito trapping was discontinued the week ending September 22, 2007.)

Mosquito samples from the following communities have tested positive for WNV in 2007: Altona, Beausejour, Boissevain, Brandon, Carberry, Carman, Dauphin, Deloraine, East St. Paul, Gimli, Headingley, Killarney, Minnedosa, Morden, Morris, Niverville, Oakbank, Peguis First Nation, Portage la Prairie, Roblin, Russell, St. Andrews, Ste. Anne, Sandy Bay First Nation, Selkirk, Sioux Valley First Nation, Souris, Steinbach, Stonewall, Stony Mountain, Virden, West St. Paul, Winkler, Winnipeg, and Winnipeg Beach.

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WNV Human Cases by Regional Health Authority 2007*

Represents the Regional Health Authority of residence of the patient.

West Nile Related Deaths:  In 2007, there were four human deaths related to a West Nile virus infection in Manitoba. All four were male individuals.  Three were in their sixties or older and one was in his forties. One was a resident of Assiniboine health region, one of Central health region, one of Interlake health region, and one of Winnipeg health region.

* As of February 14, 2008.

Note: For the above table and the two following tables, 2007 human case classifications include both final and preliminary classifications and may be subject to change as further information becomes available.

The most likely locations of exposure have been determined for at least one human case in each of the following municipalities: RM of Alexander, RM of Bifrost, RM of De Salaberry, RM of East St. Paul, RM of Lac du Bonnet, Town of Morden, Town of Morris, RM of North Norfolk, RM of Park, RM of Portage la Prairie, RM of St. Clements, RM of Ste. Rose, RM of Stanley, City of Steinbach, RM of Tache, City of Winkler, City of Winnipeg, Town of Winnipeg Beach.

Further information on most likely locations of exposure will be added as it becomes available. The risk of WNV, however, exists throughout all of southern Manitoba and is not limited to the communities listed. WNV has been identified in this or previous years within the boundaries of all regional health authorities except for NOR-MAN, Burntwood, and Churchill.

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Severity of WNV Disease By Age 2007*

Average Age - Asymptomatic West Nile Virus: 47
Average Age - West Nile Virus Non Neurological Syndrome : 48
Average Age - West Nile Virus Neurological Syndrome: 56

* As of February 14, 2008.

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WNV Disease by Gender 2007*

* As of February 14, 2008.

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Additional information and maps are available at the Public Health Agency of Canada website.

For WNV health concerns, contact your doctor or call:

Health Links - Info Santé
204-788-8200 (Winnipeg) or toll-free 1-888-315-9257