2006 Surveillance for West Nile virus in Manitoba
- Positive Surveillance Indicators
- Culex tarsalis Mosquito Trap Catch by Regional Health Authority
- Positive Mosquito Collections (Adult) by RHA
- WNV Patients by Regional Health Authority
- Severity of WNV Disease by Age
- WNV Disease by Gender
Positive Surveillance Indicators*
| Surveillance Indicator | 2006* | 2005 | 2004 | 2003 | 2002 |
| Corvids ** | __ | 12 | 16 | 134 | 86 |
| Mosquito Collections (Adult) | 171 | 193 | 57 | 290 | 15 |
| Horse Cases | 1 | 4 | 0 | 47 | 236 |
| Human Cases (Classified) | 51 | 58 | 3 | 143*** | 0 |
* As of December 7, 2006.
** The West Nile virus dead corvid pick up program was not n effect in 2006. 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.
*** Updated in 2005 after receiving a late report on a Manitoba resident with WNV who was investigated in Saskatchewan in 2003.
Culex tarsalis Mosquito Trap Catch by Regional Health Authority 2006*
| Average Adult Culex tarsalis Mosquitoes per Weekly Trap Catch | |||||
| Regional Health Authority | June 4-10 | June 11-17 | June 18-24 | ||
| Assiniboine | <1 | <1 | <1 | ||
| Brandon | <1 | <1 | <1 | ||
| Central | 5 | 3 | 2 | ||
| Interlake | 10 | 2 | 3 | ||
| North Eastman | 4 | <1 | 3 | ||
| Parkland | 0 | <1 | <1 | ||
| South Eastman | 6 | 1 | 2 | ||
| Winnipeg | 13 | 2 | 1 | ||
| Regional Health Authority | June 25-July 1 | July 2-July 8 | July 9-July 15 | ||
| Assiniboine | 2 | 6 | 4 | ||
| Brandon | <1 | 2 | 8 | ||
| Central | 11 | 15 | 8 | ||
| Interlake | 14 | 33 | 24 | ||
| North Eastman | 5 | 14 | 9 | ||
| Parkland | <1 | <1 | 0 | ||
| South Eastman | 4 | 13 | 13 | ||
| Winnipeg | 18 | 21 | 19 | ||
| Regional Health Authority | July 16-July 22 | July 23-July 29 | July 30-Aug 5 | ||
| Assiniboine | 8 | 22 | 136 | ||
| Brandon | 10 | 31 | 42 | ||
| Central | 9 | 15 | 15 | ||
| Interlake | 37 | 70 | 43 | ||
| North Eastman | 20 | 17 | 11 | ||
| Parkland | 0 | <1 | 1 | ||
| South Eastman | 11 | 15 | 5 | ||
| Winnipeg | 50 | 83 | 98 | ||
| Regional Health Authority | Aug 6-Aug 12 | Aug 13-Aug 19 | Aug 20-Aug 26 | ||
| Assiniboine | 36 | 25 | 13 | ||
| Brandon | 47 | 4 | 5 | ||
| Central | 11 | 7 | 2 | ||
| Interlake | 32 | 7 | 1 | ||
| North Eastman | 9 | 7 | 1 | ||
| Parkland | 1 | 0 | 0 | ||
| South Eastman | 6 | 3 | 1 | ||
| Winnipeg | 64 | 12 | 4 | ||
| Regional Health Authority | Aug 27-Sept 2 | Sept 3 -Sept 9 | Sept 10 -Sept 16 | ||
| Assiniboine | 2 | <1 | <1 | ||
| Brandon | 2 | <1 | <1 | ||
| Central | <1 | <1 | <1 | ||
| Interlake | <1 | 0 | <1 | ||
| North Eastman | <1 | <1 | 0 | ||
| Parkland | 0 | 0 | <1 | ||
| South Eastman | <1 | 0 | 0 | ||
| Winnipeg | 2 | <1 | <1 | ||
* As of December 7, 2006. (Routine mosquito trapping ended the week of September 10, 2006.)
Permanent mosquito traps are set up in 36 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.
Positive Mosquito Collections (Adult) by RHA 2006
| Positive Mosquito Collections (Adult) by RHA 2006 | |
| Assiniboine | 34 |
| Brandon | 7 |
| Central | 7 |
| Interlake | 40 |
| North Eastman | 9 |
| Parkland | 0 |
| South Eastman | 4 |
| Winnipeg | 70 |
| Total | 171 |
* As of December 7, 2006.
Mosquito samples from the following communities have tested positive for WNV in 2006: Altona, Beausejour, Boissevain, Brandon, Carberry, Carman, Deloraine, East St. Paul, Gimli, Headingley, Killarney, Niverville, Oakbank, Portage la Prairie, St. Andrews, Selkirk, Sioux Valley First Nation, Steinbach, Stony Mountain, West St. Paul, Winkler, and Winnipeg.
WNV Human Cases by Regional Health Authority 2006*
Represents the Regional Health Authority of residence of the patient.
Regional Health Authority |
Asymptomatic |
West Nile Virus Non-Neurological Syndrome |
West
Nile Virus |
Under Investigation |
TOTAL |
| Assiniboine | 0 | 6 | 0 | 0 | 6 |
| Brandon | 0 | 0 | 0 | 0 | 0 |
| Burntwood | 0 | 1 | 0 | 0 | 1 |
| Central | 0 | 9 | 2 | 0 | 11 |
| Interlake | 1 | 5 | 5 | 0 | 11 |
| N. Eastman | 0 | 1 | 1 | 0 | 2 |
| Parkland | 0 | 0 | 0 | 0 | 0 |
| S. Eastman | 0 | 1 | 2 | 0 | 3 |
| Winnipeg | 0 | 10 | 7 | 0 | 17 |
| Total | 1 | 33 | 17 | 0 | 51 |
* As of December 7, 2006.
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 Armstrong, RM of Brokenhead, RM of Cartier, RM of Clanwilliam, RM of Coldwell, RM of De Salaberry, RM of East St. Paul, RM of Louise, RM of MacDonald, Town of Morden, RM of North Cypress, RM of Pilot Mound, RM of Portage la Prairie, RM of Rockwood, RM of St. Andrews, RM of Ste. Anne, RM of St. Clements, City of Selkirk, RM of Stanley, Town of Stonewall, RM of Turtle Mountain, RM of Victoria Beach, City of Winnipeg, RM of Woodlands.
Further information on 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.
Severity of WNV Disease By Age 2006*
| Age in Years | Asymptomatic | West Nile Virus Non-Neurological Syndrome | West
Nile Virus Neurological Syndrome |
Under Investigation | Total |
| 0 - 9 | 0 | 0 | 0 | 0 | 0 |
| 10 - 19 | 0 | 1 | 0 | 0 | 1 |
| 20 - 29 | 1 | 1 | 1 | 0 | 3 |
| 30 - 39 | 0 | 4 | 1 | 0 | 5 |
| 40 - 49 | 0 | 9 | 6 | 0 | 15 |
| 50 - 59 | 0 | 10 | 4 | 0 | 14 |
| 60 - 69 | 0 | 4 | 1 | 0 | 5 |
| Over 70 | 0 | 4 | 4 | 0 | 8 |
| Total | 1 | 33 | 17 | 0 | 51 |
Average Age - West Nile Virus Neurological
Average Age - West Nile Virus Non-Neurological
Syndrome: 51
* As of December 7, 2006.
WNV Disease by Gender 2006*
| Gender | Asymptomatic | West Nile Virus Non-Neurological Syndrome | West Nile Virus Neurological Syndrome |
Under Investigation |
Total |
| Male | 0 | 24 | 9 | 0 | 33 |
| Female | 1 | 9 | 8 | 0 | 18 |
| Total | 1 | 33 | 17 | 0 | 51 |
* As of December 7, 2006.
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
