Utilizing Historical Mosquito Surveillance Data To Investigate The Efficacy Of Municipal Fogging In Controlling Mosquito Population Density

Background: Mosquito borne diseases are the cause of many different disease syndromes and deaths in animals, both wild and domesticated, and humans of all ages and ethnicities. Though El Paso, TX is located in an arid region, mosquito populations are still rapidly growing in urban and agricultural communities and so are the mosquito borne illnesses. The most common vectors associated with mosquito borne illnesses in El Paso County are Culex quinquefasciatus, Culex tarsalis, and Aedes aegypti. Vector management is often the primary option to prevent and control outbreaks of mosquito borne illnesses and very often utilize fogging as the primary method to do so. Objective: The goal of the study was to investigate the effectivity of mosquito fogging completed by El Paso Vector Control in reducing mosquito population densities in agro-urban environments and preventing mosquito borne diseases. Effectivity was estimated by determining the statistically significant differences in mosquito population density after fogging treatment compared to historical data for the same sampled environments when not fogged. Methods: Collaboration with the department of El Paso, TX environmental services vector control program and the biosciences Mosquito Ecology and Surveillance Laboratory (MESL) at the University of Texas at El Paso was done via data compilation from both sources for mosquito surveillance results. Historical mosquito surveillance data from the years 2015 and 2016 were retrieved from the MESL mosquito collection sites selected due to the relative proximity of a standing water reservoirs, ditches, canalsâ?¦etc. Vector Control geographic informational system activity map was used to identify fogging times near these locations during 2015-2016. Historical mosquito surveillance data was statistically compared against fogging status to assess if there was a significant decrease in mosquito population density that could prevent mosquito borne disease outbreaks. Results: During 2015, usual fogging procedures, which was sporadic, showed no significant difference in overall mean vector abundance within agro-urban or flood prone areas, yet in 2016 there was a significant decrease (Kruskal Wallis p=.001) in mean vector abundance in these same areas after fogging treatments per routine mosquito surveillance site. Mean mosquito count from environments that was not fogged was 57.5% higher compared to mosquito trap results that were collected within 1 week of fogging. This may be a result of increased frequency (52.6% increase of fogging compared to 2015) in neighborhoods where fogging was done near the location where traps were placed to collect mosquitoes. Along with an increase in fogging, it was also found that if the frequency of fogging was more consistent with shorter time intervals between each treatment session and therefor concentrated during the season peak mosquito abundance (August and September), more sites showed a decline in overall mosquito count not only when fogged but overall. Paradoxically though, if fogging was done minimally and sporadically, mosquito populations were found to be higher than counts when fogging had not taken place at all. According to Poisson regression analysis, overall there was a 17% decrease in female mosquito count per fogging session compared to a 39.5% increase per times the area was not fogged. Conclusion: This study suggests that data from mosquito surveillance programs that routinely collect mosquito pools for virus testing in areas being fogged by city vector control programs be used as an indicator of the effectivity of vector control procedures, on virus prevalence and/or possible virus transmission in the area as it can provide information on the practical application and real world effect of such procedures. Results of the analysis were converted into a geographical informational system and submitted to El Paso Vector Control along with a regression analysis and report for future mosquito control reference. Keywords: Vector Control, Mosquito Borne Illness, Effectivity, El Paso TX, GIS, Mosquito Surveillanc