Ottawa Public Health (OPH) has received reports of 13 human cases of West Nile virus (WNV) illness in Ottawa residents as of September 18. The previous highest number of WNV cases in Ottawa was 8 in 2012. With temperatures well above average for this time of year, mosquitoes carrying WNV continue to bite humans. OPH is advising residents to protect themselves against mosquito bites. Mosquitoes most likely to transmit WNV (Culex pipiens, the northern house mosquito) are found in urban areas in and around homes. Testing has shown mosquitoes carrying WNV in all the urban areas of Ottawa. These mosquitoes will pose a risk on warm days until there have been several hard frosts.
Most people infected with WNV will not develop any symptoms if infected with WNV, but about 20 per cent may experience flu-like symptoms including fever, headache, muscle aches, and, possibly, a rash. The risk for more serious illness—occurring in less than 1 per cent of infections in which WNV invades the central nervous system—increases with increasing age, with older adults and the elderly as well as people with weakened immune systems being at higher risk.
In Ontario this year, as of September 16, there have been 98 human cases. In 2016, there were two human cases in Ottawa, and 55 human cases in Ontario.
OPH urges residents to in protect themselves and their families from mosquito bites by:
- Applying a Health Canada-approved mosquito repellent containing DEET or icaridin to exposed skin and clothing
- Protecting yourself especially between dusk and dawn, periods when mosquitoes are most active, and at any time in or near shady, bushy or wooded areas
- Wearing light-coloured, tightly woven, loose-fitting clothing such as long pants, a long-sleeved shirt, shoes and socks to protect exposed skin
- Making sure all windows and doors in your home have screens that are in good condition
- Reducing standing water sites around your home (bird baths, toys, flower pot saucers, swimming pool covers, old tires, wheelbarrows, buckets, cans, etc.)
- Ensuring all openings to rain barrels are covered with screen mesh at all times
OPH has a proactive plan to deal with WNV that includes weekly surveillance and, when necessary, mosquito larvicidal treatment of natural and man-made standing water sites located on City property, such as ditches and storm water management ponds. As part of this plan, OPH also has regular applications of larvicide in City-owned roadside storm sewer catch-basins to reduce the mosquito population.
For additional information on West Nile Virus, visit OttawaPublicHealth.ca or call Ottawa Public Health Information at 613-580-6744 (TTY: 613-580-9656). You can also connect with us on Facebook and Twitter (@ottawahealth).