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IN THIS ISSUE
 WNv Surveillance in Ontario
This issue is the first of the Ontario WNv Bulletin for this year. Its purpose is to provide some background information and a summation of the results of the various surveillance activities in Ontario from the year 2000. Additionally, the issue will update on other findings elsewhere in Canada and in the U.S. This issue will also outline the changes Ontario has made to its 2001 Surveillance Programs since 2000.
Update of Year 2000 WNv Activities in Ontario
Sentinel Chicken Surveillance
On October 13, 2000, the sentinel chicken component of the WNv Surveillance Program closed for the season, at which point none of the chickens had become infected with WNv. It was during the 2000 mosquito season that sentinel chickens were used to determine whether they would be equally successful in the early detection of WNv. Approximately 600 sentinel chickens were used to monitor for evidence of WNv during the 2000 season in strategic locations spanning from Saskatchewan to Atlantic Canada. American evidence last year indicated that sentinel chicken surveillance did not detect WNv prior to dead bird or human surveillance. WNv was not detected in any sentinel chickens tested in Canada. As a result of these findings, Ontario is not conducting sentinel chicken surveillance for 2001. However, sentinel chicken surveillance for Western Equine Encephalitis is in place to also assess for WNv in the provinces of Manitoba and Saskatchewan. Therefore, the focus for early detection of WNv activity is for the public to report, and public health workers to submit dead corvids for WNv testing. Human Encephalitis Surveillance
Active surveillance for human meningo-encephalitis from sentinel hospitals ceased at the end of October 2000. As October 20, 2000, 174 individuals, ranging from 2 months to 92 years of age, were deemed suspect cases for WNv. Both community physicians and sentinel hospital physicians reported these cases through enhanced passive surveillance and active surveillance. At the end of the 2000 surveillance season, no human cases of WNv infection had been confirmed in Ontario. Mosquito Surveillance
As of October 14, 2000, the mosquito component of the surveillance for the season was discontinued. Dead Bird Surveillance
The Ontario Region Laboratory of the Canadian Cooperative Wildlife Health Centre (CCWHC) in Guelph ceased to accept dead bird submissions for WNv testing for the 2000 season as of October 6, 2000. For the 2000 surveillance season, the CCWHC received a total of 1531 dead bird submissions for WNv. During the 20 weeks of observation, the number of dead birds submitted was 64 per week (range of 2 to 462). None of the 1531 dead birds were found to be positive for WNv. The CCWHC has reported that as of February 1, 2001, the virus had not been found in any of the 2,288 birds in Canada examined since the introduction of the dead bird surveillance program. Some tests are still underway on samples from birds that were not tested for the virus initially.
WNv Activities in Ontario for the Year 2001
Sentinel Chicken Surveillance
The testing and monitoring of sentinel chickens for the purpose of predicting areas in which WNv exists, is no longer conducted.
Human Encephalitis Surveillance
Similar to the activities implemented in 2000, Health Canada has asked that key health care providers, including family and emergency room physicians, infectious disease specialists and neurologists, monitor their patients for symptoms of WNv in 2001. These health care professionals are being asked to promptly report any probable and confirmed cases of viral encephalitis to local/provincial public health authorities. REMINDER
Mosquito Surveillance
Mosquito surveillance will be implemented in areas from which a dead bird has tested positive for WNv.
Dead Bird Surveillance
The 2001 Dead Bird Surveillance season has begun, with a total of 463 reported dead bird sightings and/or submissions as of June 5, 2001. Of these 463 birds, 238 were submitted to the lab in Guelph for WNV testing, while 140 of those submitted to Guelph were sent to the lab in Winnipeg. Attached are two maps, which contain the number of birds submitted for testing in both Ontario and in Eastern Canada (Saskatchewan and East). These maps will be provided weekly to health units and reported in each issue of the WNv Bulletin.
The following table lists the bird species in the U.S. from which WNv was confirmed. Table 1. North American Bird Species in which WNv was identified in 19991
From the National Wildlife Health Center, U.S. Geological Survey, Madison WI, October 1999. * Indicates the bird was in captivity. Source : CCWHC Web site. (May 23, 2001)
Figure 2. Types of Ontario Dead Birds Sighted/Tested in 2001 Season as of June 5, 2001 
Figure 3. Number of Dead Bird Sightings in/Submissions by Ontario Health Units as of June 5, 2001(n=463) NOTE : These are health unit submissions to the lab in Guelph, not to the lab in Winnipeg.
Other News
Worldwide Geographic Distribution
According to the CDC, WNv has been described worldwide in Africa, Europe, the Middle East, west and central Asia, Oceania (subtype Kunjin), and most recently, North America.
Health & Medical Breakthroughs
The U.S. government has enlisted the help of Acambis, a small Cambridge-based British biotechnology firm, to help fight WNv by producing a vaccine suitable for use in both humans and animals. They are gearing up for human trials of their experimental vaccine, as they are currently in the final stages of animal testing. Although representatives from Acambis are hopeful, they indicate that the vaccine is still "3 or 4 years from reaching the market, even if it successfully completes clinical trials."(Reuters) The similarity between the Yellow fever and West Nile viruses allowed Acambis to utilize the Yellow Fever vaccine, which has been touted as the safest anti-viral vaccine, as a backbone for the experimental WNv vaccine. Since there is currently no cure for WNv, this is the closest scientists have come to battling the disease from a therapeutic standpoint. North American Geographic Distribution
Although WNv has not been documented in Canada, American officials have documented the virus in 2000 in Connecticut, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, the District of Columbia, and North Carolina. To date, there are 17 states with active WNv surveillance programs, with positive specimens already testing positive for WNv. U.S. :
Human cases : During the year 2000, a total of 21 human cases tested positive for the WNv infection in the U.S.: 14 in New York State, 6 in New Jersey, and an additional 1 case in Connecticut. These cases included the 2 deaths attributed to the virus: one in the state of New York and one in the state of New Jersey. As of June 4, 2001, there have been no reported human cases of WNv in the U.S.. Birds :
Table 2. The number of dead birds that tested positive in the U.S. as of June 1, 2001.
Source : Reported to CDC Atlanta, USA via Arbo-NET as of Noon MST, June 1, 2001.
Maps
Acknowledgements
The contribution of the following agencies and individuals in the publication of this year's issues of the WNv Bulletin is greatly appreciated :
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Comments, questions and suggestions about surveillance results in this bulletin should be directed to : Danielle Stein, Acting WNv Surveillance Coordinator, Disease Control Service, Tel: 416 327-7452, E-mail : danielle.stein@moh.gov.on.ca Dr. Dean Middleton, Veterinary Consultant, Disease Control Service, Tel: 416-327-7422, E-mail : dean.middleton@moh.gov.on.ca | |
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