St. Tammany Parish Mosquito Abatement (STPMAD) has collected mosquitoes that have tested positive for infection with West Nile virus (WNV) for the first time this year. The Louisiana Animal Disease Diagnostic Laboratory (LADDL), at the LSU School of Veterinary Medicine reported that this is the first WNV infected pool of mosquitoes in the state for 2019. The infected mosquitoes were collected from traps in the Covington neighborhood of Tammany Hills over the last two weeks. The presence of WNV in mosquitoes indicates an elevated risk to people in the area. Residents in the Covington area can expect to see increased mosquito abatement efforts, including daytime larval inspections and treatments, helicopter larviciding and nighttime mosquito spraying with trucks and airplanes.
Beginning May 21st, St. Tammany Parish Mosquito Abatement began using a helicopter to distribute larvicide aerially over the Tammany Hills neighborhood. The preliminary results have found that the larvicide is working well in container environments, however, the impacts on larval mosquitoes in roadside septic ditches is still being assessed. In 2018, 20% of West Nile virus infected mosquito pools came from traps located within this neighborhood. Tammany Hills has a high density of individual onsite-septic systems, and in many cases effluent from non-functioning systems is being piped directly into the roadside ditches creating the ideal habitat for the Culex quinquefasciatus.
St. Tammany Parish Mosquito Abatement collects mosquitoes from over ninety sites across the parish from February through November. Collected mosquitoes are identified to species, counted, and submitted in groups or sample pools for virus testing to the LADDL, at the LSU School of Veterinary Medicine. 1 of the 89 sample pools submitted last week tested positive for WNV. In 2019 to date, STPMAD has tested over 1631 samples.
West Nile virus is a mosquito-transmitted pathogen that primarily infects birds. Occasionally bird-biting mosquitoes may bite people and transmit WNV to a human. The primary vector of WNV in South Louisiana is the southern house mosquito, Culex quinquefasciatus, which feeds on birds about 80% of all blood meals and rears its larvae in organically rich water. St. Tammany Parish has over 400 miles of septic roadside ditches that receive treatment to control larvae of the southern house mosquito every five days during the summer.
We ask residents to do their part to reduce their risk of contracting WNV by making certain their septic systems are in proper working order, including having them pumped out if necessary, and checking to make certain aerators are operable. Also, controlling the vegetation in the ditches helps to allow the larval control treatments to reach the water surfaces. Finally, avoiding or minimizing exposure to biting mosquitoes by: 1) wearing CDC recommended mosquito repellent such as those containing DEET, picaridin, or oil of lemon eucalyptus; 2) avoiding peak biting times such as one hour prior to and after dusk and dawn; and 3) wearing long sleeve shirts and pants.