Routine mosquito-borne disease surveillance conducted by the Saginaw County Mosquito Abatement Commission (SCMAC) has detected the first evidence of both West Nile virus (WNV) and Jamestown Canyon virus (JCV) in mosquitoes this year. The WNV detection was found in Culex mosquitoes, while JCV was found in Aedes mosquitoes both collected within Saginaw County in May. These are the first detections of mosquito-borne virus activity found in Saginaw County this 2019 season. These early detections of mosquito-borne virus, while very low within mosquito populations, remind us that mosquitoes can be more than just a nuisance, and precautions should be taken to avoid mosquito bites.
Mosquito-borne virus monitoring will continue through the end of September via testing certain mosquito samples for five viruses associated with Michigan’s mosquito population; viruses include West Nile, Jamestown Canyon, La Crosse encephalitis, St. Louis encephalitis, and Eastern Equine encephalitis. West Nile virus surveillance also includes the testing of reported dead crows and blue jays. Any areas in the county with elevated levels of mosquito-borne virus activity will receive extensive control efforts to reduce adult and larval mosquito populations. Citizens are encouraged to take appropriate measures to avoid mosquitoes and are strongly encouraged to contact the Commission’s office at (989) 755-5751 if they notice a crow or blue jay that has been dead for less than 24 hours.
West Nile virus is found annually in Saginaw County since its introduction in 2002, and is known to be primarily transmitted by Culex mosquitoes. Jamestown Canyon virus, a re-emerging mosquito transmitted virus, can be found in many mosquito species, known to bite people. Mosquito-borne viruses are transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird or mammal host. Human infections are rarely diagnosed as the majority of infections result in no symptoms (asymptomatic). When symptoms present they include sudden onset of flu-like illness with fever. Severe cases, although rare, may develop neurologic symptoms such as meningitis or encephalitis requiring hospitalization. The best way to prevent mosquito-borne disease is to protect yourself and family from mosquito bites:
• Avoid being outdoors when mosquitoes are most active, especially between dusk and dawn.
• When outdoors wear shoes and socks, light colored long pants, and a long-sleeved shirt. Apply an insect repellent that contains DEET, picaridin, or IR3535 according to label instructions. Consult a physician before using repellents on infants. Only use products that are registered by the Environmental Protection Agency.
• Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut, especially at night.
• Eliminate all sources of standing water that can support mosquito breeding, including water in bird baths, neglected swimming pools, wading pools, old tires and any other object holding water. Contact SCMAC to report standing water in roadside ditches, flooded yards, fields or similar locations that may produce mosquitoes.