228 - Evaluation of truck-based adulticiding in Harris County, Texas on Culex quinquefasciatus abundance and infection with West Nile virus

Since its introduction in 2002, West Nile virus (WNV) has been reported annually in Harris County, Texas. To mitigate transmission, the Harris County Public Health Mosquito and Vector Control Division (HCPH MVCD) routinely conducts truck-based adulticiding. Previous studies in Harris County have investigated insecticide resistance in mosquitoes, compared resistance to different insecticide classes, and evaluated different forms of vector surveillance. However, long-term efficacy of adulticiding on vector populations has not been evaluated. This study utilized a time series analysis to characterize the monthly and weekly influence of adulticiding on Culex quinquefasciatus Say abundance and WNV infection over an 18-year period.  Our models were unable to
determine a consistent relationship between adulticiding and Culex abundance among the different surveillance traps and temporal scales of analysis (week and month). The models suggest a long-term negative association between adulticiding and Culex infection with WNV such that infection is lower 9-12 weeks following adulticide treatment. Further studies should continue to investigate the efficacy of truck and aerial adulticiding for the management of WNV using improved study designs for building the evidence base for assessing vector control interventions.