Prepared By:
Amandeep Hans, Health Promotion Specialist, Environmental Health Department
Date:
May 2019
Subject:
Vector-Borne Diseases
Background
The Environmental Health Department conducts annual monitoring and testing of tick and mosquito populations in Windsor and Essex County (WEC) as part of the WECHU’s Zoonotic and Vector-borne Diseases Program.
Mosquito Surveillance and Testing
Adult mosquito surveillance is an important component of the Zoonotic and Vector-borne Diseases Program. Surveillance runs from May to early October every year and may extend depending on the weather and temperatures. Species-specific traps are deployed in various locations throughout WEC to capture mosquitoes for testing and identification to determine the presence of West Nile and Zika Virus in our communities. In 2018, the Environmental Health Department collected samples from almost 1000 mosquito traps, identifying and testing over 80,000 mosquitoes by the end of the season. Invasive mosquito species Aedes aegypti (Yellow Fever Mosquito) and Aedes albopictus (Asian Tiger Mosquito) are also monitored each year through our Enhanced Mosquito Surveillance Program. These species are known carriers of diseases such as Zika, Malaria, Dengue, and Chikungunya. There were over 1000 invasive mosquitoes identified and tested in 2018, which is a 200% increase from the previous year. Due to the increased numbers of Asian Tiger Mosquitoes noted during trapping, the Public Health Agency of Canada (PHAC) has determined the City of Windsor and Essex County to be endemic for these mosquitoes.
Mosquito Control
The mosquito control program involves applying larvicide to catch basins and standing water sites such as ditches and lagoons that hold water. All municipalities in WEC have standing water by-laws in place. Last year over 133,000 treatments of larvicide were applied to roadside catch basins and standing water sites. Targeted treatment was also conducted for identified “hot spots” during the summer season. A “hot spot” would be a location where,
- Invasive mosquito species have been identified,
- Positive samples for West Nile Virus found or,
- Clusters of human cases of West Nile Virus have been confirmed.
Human Cases
The WECHU follows up on all human cases of West Nile Virus. Cases are investigated to assess if additional mosquito control activities are required. If a cluster of cases is identified, the Environmental Health Department will increase mosquito control and surveillance activities. To date there have been no human cases of Zika Virus identified in WEC.
Ticks and Lyme Disease
The WECHU’s role is to measure and evaluate the risk of tick-borne disease in our area through both passive and active tick surveillance activities. Our surveillance data in the last 3 years indicates an increase in black-legged ticks (Ixodes scapularis) in WEC. The black-legged tick is the main vector for Borrelia burgdorferi, the bacteria that causes Lyme disease.
Passive surveillance involves residents submitting ticks to the health unit for identification and subsequent testing if the ticks are identified as blacklegged. Last year, 339 ticks were submitted to the WECHU, 31 were identified as blacklegged ticks and two of these ticks tested positive for Borrelia burgdorferi.
Active surveillance involves active field surveillance from Environmental Health staff. Active surveillance is usually conducted in the spring and fall seasons in parks and on trails that are frequented by the community. Black- legged ticks that are identified in both the spring and fall would indicate that the area is potentially endemic. There were 12 blacklegged ticks identified when active surveillance was conducted at the Ojibway Prairie Nature Reserve and Chrysler Greenway in 2018
Tick Control
There is no formalized tick control program for our local parks and trails. Ticks are transported around by birds, deer and other wildlife and are not very mobile. Education is provided to the general public on tick removal and signs and symptoms for Lyme Disease.
Human Cases
In 2018, there were nine cases of Lyme disease in WEC. All laboratory confirmed cases are interviewed to determine where they may have encountered black-legged ticks. Any local parks or trails that are noted during the investigation would prompt active surveillance.
Current Initiatives
In addition to continued surveillance and monitoring efforts, the WECHU will be launching a Fight the Bite public awareness campaign in June 2019. The awareness campaign will focus on prevention of mosquito breeding sites as well as personal protection. Targeted promotion and messaging will be used to reach priority populations and inform the public of hot spots identified through previous monitoring efforts.
Consultation
The following individuals were contributed to this report:
- Kristy McBeth, Director, Health Protection
- Phil Wong, Manager, Environmental Health Department
- Saamir Pasha, Epidemiologist, Epidemiology and Evaluation Department
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Approved by:
Theresa Marentette