2009 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
2009 Positive Surveillance Indicators*
| Surveillance Indicator | 2009 | 2008 | 2007 | 2006 |
| Corvids 1 | __ | __ | __ | __ |
| Mosquito Collections (Adult) | 2 |
41 |
948 | 171 |
| Horse Cases | 0 |
0 |
8 | 1 |
| Human Cases (Total) 2 | 2 | 12 | 587 | 51 |
| Surveillance Indicator | 2005 | 2004 | 2003 | 2002 |
| Corvids 1 | 12 | 16 | 134 | 86 |
| Mosquito Collections (Adult) | 193 | 57 | 290 | 15 |
| Horse Cases | 4 | 0 | 47 | 236 |
| Human Cases (Total) 2 | 58 | 3 | 143 | 0 |
* As of November 5, 2009.
1 The West Nile virus dead corvid pick up program is not in effect in 2009. 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.
2Additional information on these cases including classification, age, gender, regional health authority of residence and likeliest area of exposure is available here.
Culex tarsalis Mosquito Trap Catch by Regional Health Authority*
| Average Adult Culex tarsalis Mosquitoes per Weekly Trap Catch | |||||
| Regional Health Authority | May 17 - |
May 24 - |
May 31 - June 6 |
||
| Assiniboine | 0 | 0 | <1 | ||
| Brandon | 0 | 0 | 0 | ||
| Central | 0 | 0 | <1 | ||
| Interlake | 0 | 0 | 0 | ||
| North Eastman | 0 | 0 | 0 | ||
| Parkland | 0 | 0 | 0 | ||
| South Eastman | 0 | <1 | 0 | ||
| Winnipeg | 0 | 0 | <1 | ||
| Manitoba | 0 | <1 | <1 | ||
| Regional Health Authority | June 7 - |
June 14 - June 20 |
June 21 - June 27 |
||
| Assiniboine | 0 | 0 | 1 | ||
| Brandon | 0 | 0 | <1 | ||
| Central | 0 | 0 | 2 | ||
| Interlake | 0 | 0 | 2 | ||
| North Eastman | 0 | 0 | 1 | ||
| Parkland | 0 | 0 | <1 | ||
| South Eastman | 0 | 0 | 1 | ||
| Winnipeg | <1 | <1 | 2 | ||
| Manitoba | <1 | <1 | 1 | ||
| Regional Health Authority | June 28 - |
July 5 - |
July 12 - |
||
| Assiniboine | 2 | 2 | 10 | ||
| Brandon | <1 | 1 | <1 | ||
| Central | <1 | 6 | 9 | ||
| Interlake | <1 | <1 | 3 | ||
| North Eastman | 0 | <1 | <1 | ||
| Parkland | 1 | 0 | <1 | ||
| South Eastman | <1 | <1 | 3 | ||
| Winnipeg | <1 | <1 | 4 | ||
| Manitoba | <1 | 2 | 5 | ||
| Regional Health Authority | July 19 - |
July 26 - August 1 |
August 2 - August 8 |
||
| Assiniboine | 7 | 24 | 28 | ||
| Brandon | 1 | <1 | <1 | ||
| Central | 13 | 11 | 3 | ||
| Interlake | 1 | 3 | <1 | ||
| North Eastman | 2 | 2 | <1 | ||
| Parkland | 0 | 2 | <1 | ||
| South Eastman | 2 | 4 | 1 | ||
| Winnipeg | 2 | 4 | 4 | ||
| Manitoba | 5 | 9 | 8 | ||
| Regional Health Authority | August 9 - August 15 |
August 16 - August 22 |
August 23 - August 29 |
||
| Assiniboine | 11 | 24 | <1 | ||
| Brandon | <1 | <1 | <1 | ||
| Central | 1 | 11 | 3 | ||
| Interlake | 1 | 2 | 2 | ||
| North Eastman | 1 | <1 | 1 | ||
| Parkland | 0 | <1 | 0 | ||
| South Eastman | 1 | 6 | 9 | ||
| Winnipeg | 6 | 9 | 12 | ||
| Manitoba | 5 | 10 | 4 | ||
| Regional Health Authority | August 30 - September 5 |
September 6 - September 12 | |||
| Assiniboine | <1 | <1 | |||
| Brandon | 0 | 0 | |||
| Central | <1 | <1 | |||
| Interlake | 0 | 2 | |||
| North Eastman | 0 | 3 | |||
| Parkland | 0 | 0 | |||
| South Eastman | <1 | <1 | |||
| Winnipeg | <1 | 4 | |||
| Manitoba | <1 | 1 | |||
* As of September 22, 2009.
NOTE: Routine mosquito trapping was discontinued the week ending September 12, 2009.
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.
Positive Mosquito Collections (Adult) by RHA*
| Positive Mosquito Collections (Adult) by RHA 2009 | |
| Assiniboine | 1 |
| Brandon | 0 |
| Central | 0 |
| Interlake | 0 |
| North Eastman | 0 |
| Parkland | 0 |
| South Eastman | 0 |
| Winnipeg | 1 |
| Total | 2 |
Mosquito samples from the following communities have tested positive for WNV in 2009: Boissevain and West St. Paul.
* As of September 22, 2009
NOTE: Routine mosquito trapping was discontinued the week ending September 12, 2009.
WNV Human Cases by Regional Health Authority*
Represents the Regional Health Authority of residence of the patient.
| Regional Health Authority |
Asymptomatic | West Nile Virus Non-Neurological Syndrome | West
Nile Virus Neurological Syndrome |
Unclassified Positive Test Results |
TOTAL |
| Assiniboine | 0 |
1 |
0 |
0 |
1 |
| Brandon | 0 |
1 |
0 |
0 |
1 |
| Central | 0 |
0 |
0 |
0 |
0 |
| Interlake | 0 |
0 |
0 |
0 |
0 |
| NorMan | 0 |
0 |
0 |
0 |
0 |
| North Eastman | 0 |
0 |
0 |
0 |
0 |
| Parkland | 0 |
0 |
0 |
0 |
0 |
| South Eastman | 0 |
0 |
0 |
0 |
0 |
| Winnipeg | 0 |
0 |
0 |
0 |
0 |
| Total | 0 |
2 |
0 |
0 |
2 |
| Out of Province | 0 |
0 |
0 |
0 |
0 |
The most likely locations of exposure have been determined for at least one human case in each of the following municipalities: Brandon and RM of North Cypress.
* As of November 5, 2009
Note: 2009 human case classifications include both final and preliminary classifications and may be subject to change as further information becomes available.
Severity of WNV Disease By Age*
| Age in Years | Asymptomatic | West Nile Virus Non-Neurological Syndrome | West
Nile Virus Neurological Syndrome |
Unclassified Positive Test Results |
Total |
| 0 - 9 | 0 |
0 |
0 |
0 |
0 |
| 10 - 19 | 0 |
0 |
0 |
0 |
0 |
| 20 - 29 | 0 |
0 |
0 |
0 |
0 |
| 30 - 39 | 0 |
0 |
0 |
0 |
0 |
| 40 - 49 | 0 |
0 |
0 |
0 |
0 |
| 50 - 59 | 0 |
1 |
0 |
0 |
1 |
| 60 - 69 | 0 |
0 |
0 |
0 |
0 |
| Over 70 | 0 |
1 |
0 |
0 |
1 |
| Total | 0 |
2 |
0 |
0 |
2 |
* As of November 5, 2009
Note: 2009 human case classifications include both final and preliminary classifications and may be subject to change as further information becomes available.
WNV Disease by Gender *
| Gender | Asymptomatic | West Nile Virus Non-Neurological Syndrome | West Nile Virus Neurological Syndrome |
Unclassified Positive Test Results |
Total |
| Male | 0 |
2 |
0 |
0 |
2 |
| Female | 0 |
0 |
0 |
0 |
0 |
| Total | 0 |
2 |
0 |
0 |
2 |
* As of November 5, 2009.
Note: 2009 human case classifications include both final and preliminary classifications and may be subject to change as further information becomes available.
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
