The Reminder is making its archives back to 2003 available on our website. Please note that, due to technical limitations, archive articles are presented without the usual formatting.
Based on mosquito surveillance, the time of year and the life cycle of the Culex tarsalis mosquito, the current risk of becoming infected with West Nile virus in Manitoba is considered low and is expected to decrease. While it is anticipated that additional human cases of WNV will be identified in Manitoba this season, it is expected that exposure to the virus in most newly identified cases will likely have occurred in late July or early August. Current mosquito surveillance in southern Manitoba indicates that the activity of Culex tarsalis, the main mosquito species that carries West Nile virus in Manitoba, remained low in all regional health authorities during the week of Aug. 15 to 21. The average trap counts for Culex tarsalis in regional health authorities gathered during the week of Aug. 15 to 21 were: Assiniboine, 11; Brandon, one; Central, three; Interlake, two; North Eastman, zero; Parkland, one; South Eastman, 10; and Winnipeg, 32. In 2004, infected mosquitoes have been found in the following communities: Brandon, Souris, Deloraine, Killarney, Winkler, Winnipeg, West St. Paul and East St. Paul. The infection rate of trapped mosquitoes remains low, less than one per 1,000 mosquitoes. At this time of year and during the rest of this season it is expected that newly hatched Culex tarsalis mosquitoes will not blood feed, posing little risk of WNV transmission. A total of one human case of West Nile virus infection has been identified so far this year in Manitoba. The individual has been reported to Health Canada as a probable case of West Nile neurological syndrome. Usually, people infected by West Nile virus have no symptoms and do not become ill. Of those who do become ill, most will develop West Nile fever, an illness with symptoms such as fever, headache, fatigue and body aches. Less frequently, the virus can cause more serious illness (West Nile neurological syndrome) including encephalitis, an inflammation of the brain. Encephalitis can have serious complications. These complications may include weakness, paralysis, confusion, coma and death and are more likely to occur among older adults and people with chronic diseases and weakened immune systems. There is no vaccine or specific treatment for West Nile virus. Milder symptoms of West Nile fever usually improve without medical care. Anyone experiencing severe symptoms (such as persistent high fever, muscle weakness, headache) should seek medical attention promptly for diagnosis and care. Although mosquito counts have been low, some infected mosquitoes in southern Manitoba may be active, particularly in warmer weather. Personal protection should be considered at any time when mosquito activity is noticed, especially for people over the age of 50 or with chronic medical conditions or weakened immune systems. Birds from the NOR-MAN Regional Health Authority, the Burntwood Regional Health Authority and the Churchill Regional Health Authority will continue to be considered for WNV testing to establish the presence of WNV in those areas. No further birds are required for testing from southern Manitoba.
