2004 Surveillance for West Nile virus in Manitoba
- Surveillance Indicators 2004
- WNV Patients by Regional Health
Authority 2004
- Severity of WNv Disease by Age 2004
- WNV Disease by Gender 2004
- Corvid Surveillance by Regional
Health Authority 2004
- Culex tarsalis Mosquito Trap Catch
by Regional Health Authority 2004
Positive Surveillance Indicators 2004
| Surveillance Indicator | 2004* | 2003 | 2002 |
| Corvids | 16 | 134 | 86 |
| Mosquito Collections (Adult) | 57 | 290 | 15 |
| Horse Cases | 0 | 47 | 236 |
| Human Cases | 3 | 143** | 0 |
* As of September 16, 2004
** Updated in 2005 after receiving a late report on a Manitoba resident with WNV who was investigated in Saskatchewan in 2003.
WNV Patients by Regional Health Authority 2004*
Represents the Regional Health Authority of residence of the patient.
| Regional Health Authority | Asymptomatic |
West Nile Virus Non-Neurological Syndrome |
West
Nile Virus |
Under |
TOTAL |
| Assiniboine | 0 | 2 |
0 | 0 | 2 |
| Brandon | 0 | 0 | 0 | 0 | 0 |
| Central | 0 | 0 | 0 | 0 | 0 |
| Interlake | 0 | 0 | 0 | 0 | 0 |
| N. Eastman | 0 | 0 | 0 | 0 | 0 |
| Parkland | 0 | 0 | 0 | 0 | 0 |
| S. Eastman | 0 | 0 | 0 | 0 | 0 |
| Winnipeg | 0 | 0 | 1 |
0 | 1 |
| TOTAL | 0 |
2 |
1 |
0 | 3 |
* As of September 16, 2004
Severity of WNV Disease By Age (Ave. Age 51; Age Range 14–92) 2004*
| Age in Years | Asymptomatic | West Nile Virus Non-Neurological Syndrome | West
Nile Virus Neurological Syndrome |
Under Investigation |
Total |
| Less than 30 | 0 | 1 | 0 | 0 | 1 |
| 30 - 39 | 0 | 0 | 0 | 0 | 0 |
| 40 - 49 | 0 | 1 | 0 | 0 | 1 |
| 50 - 59 | 0 | 0 | 0 | 0 | 0 |
| 60 - 69 | 0 | 0 | 1 | 0 | 1 |
| Over 70 | 0 | 0 | 0 | 0 | 0 |
| Totals | 0 | 2 | 1 | 0 | 3 |
*As of September 16, 2004
WNV Disease by Gender 2004*
| Gender | Asymptomatic | West Nile Virus Non-Neurological Syndrome | West
Nile Virus Neurological Syndrome |
Under Investigation |
Total |
| Male | 0 | 1 | 1 | 0 | 2 |
| Female | 0 | 1 | 0 | 0 | 1 |
| Total | 0 | 2 | 1 | 0 | 3 |
*As of September 16, 2004
Corvid Surveillance by Regional Health Authority 2004*
Regional Health Authority |
Number
of birds |
Number
of birds |
| Winnipeg | 142 | 7 |
| Parkland | 16 | 1 |
| Interlake | 37 | 2 |
| Assiniboine | 24 | 1 |
| Central | 30 | 1 |
| North Eastman | 41 |
1 |
South Eastman |
20 |
3 |
| Brandon | 20 | 0 |
| Nor-Man | 12 |
0 |
| Burntwood | 10 |
0 |
| Churchill | 0 |
0 |
Total |
352 |
16 |
* As of September 16, 2004
Birds from the crow family (corvids) are very susceptible to WNV. Many die soon after becoming infected. Testing dead crows and other corvids provides an early indication of the presence of infected mosquitoes in an area.
Culex tarsalis Mosquito Trap Catch by Regional Health Authority 2004*
| Average Adult Culex tarsalis Trap Catch Summary by RHA | |||
| Culex tarsalis | Sept
5 - Sept 11 |
Aug.
29 - Sept 4 |
August
22 - August 28 |
| Assiniboine | ** | 0 | 1 |
| Brandon | ** | 1 | 1 |
| Central | 0 | 0 | 3 |
| Interlake | 0 | 0 | 0 |
| North Eastman | 0 | 0 | 0 |
| Parkland | 0 | 0 | 0 |
| South Eastman | 0 | 0 | 1 |
| Winnipeg | 2 | 1 | 1 |
| Culex tarsalis | August 15 - August 21 | August 8 - August 14 | August 1 - August 7 |
| Assiniboine | 11 | 17 | 284 |
| Brandon | 1 | 4 | 84 |
| Central | 3 | 2 | 39 |
| Interlake | 2 | 1 | 10 |
| North Eastman | 0 | 1 | 4 |
| Parkland | 1 | 8 | 11 |
| South Eastman | 10 | 2 | 36 |
| Winnipeg | 32 | 32 | 68 |
| Culex tarsalis | July
25 - July 31 |
July
18 - July 24 |
July 11 - July 17 |
| Assiniboine | 215 | 292 | 93 |
| Brandon | 237 | 21 | 35 |
| Central | 186 | 27 | 30 |
| Interlake | 8 | 10 | 1 |
| North Eastman | 127 | 16 | 5 |
| Parkland | 62 | 6 | 2 |
| South Eastman | 289 | 70 | 20 |
| Winnipeg | 115 | 39 | 192 |
| Culex tarsalis | July
4 - July 10 |
June
27 - July 3 |
June
20 - June 26 |
| Assiniboine | ** | 1 | 0 |
| Brandon | ** | 0 | 0 |
| Central | 5 | 3 | 0 |
| Interlake | 1 | 1 | 0 |
| North Eastman | 0 | 0 | 0 |
| Parkland | ** | 0 | 0 |
| South Eastman | 4 | 1 | 0 |
| Winnipeg | 0 | 0 | 1 |
* As of September 16, 2004. Final averages subject to
change based on incoming data.
** Trapping not underway during
this period
Permanent mosquito traps will be set up in 30 sites 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 represents 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 or three Centers for Disease Control (CDC) mosquito traps baited with carbon dioxide are run for one or 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.
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
