The first CARERC pilot award was granted in late 2012 to Dr. Stephanie L. Richards (PD/PI) and Dr. Jo Anne G. Balanay (Co-PI) of East Carolina University for their intervention project, Effectiveness of insecticide-treated clothing to prevent tick and mosquito exposure in foresters and loggers in western North Carolina.
Insect bites are a common occupational hazard for outdoor workers, and the extent to which exposures are linked to vector borne disease is not fully understood. Ticks and mosquitoes are known to transmit pathogens that cause diseases such as Rocky Mountain spotted fever (tick), Lyme Disease (tick), West Nile fever (mosquito), and Eastern equine encephalitis (mosquito). While spray-on and/or lotion-based repellants can be applied directly to skin and/or clothing, repellant/insecticide-treated clothing is also available. The primary goal of this study was to assess risk and initiate further development of means to reduce infectious disease exposures among forestry workers in Central Appalachia.
Exposure risk was characterized, in part, based on count and relative abundance of species known to blood feed on and transmit pathogens to humans. Ticks and mosquitoes were collected at study sites, identified as to species, and frozen for future pathogen analysis. Participants received instructions about reporting exposure and were asked to submit personal work uniforms to be professionally treated with insecticide/repellant. The study was approved under ECU Institutional Review Board (IRB) protocol UMCIRB 12-001780 effective 2012 Oct 3.
As of August 2013, nearly three dozen foresters had been enrolled (KY, N=2; NC, N=12; TN, N=3; VA, N=14; WV, N=3). A total of 332 mosquitoes representing three genera and eight species were collected by researchers in May and June 2013. The most commonly collected mosquito species were Aedes vexans (56%) and Culex restuans (20%). A total of 454 ticks were collected by foresters during the study period from May to June 2013. The majority of ticks collected were Amblyomma americanum (91.5%), followed by Dermacentor variabilis (6.7%), Rhipicephalus sanguineus (< 1%), and Ixodes scapularis (1%).
A non-time weighted tick bite rate (number of participants receiving at least one tick bite/the total number of participants in each group) showed that 85% of control group participants received tick bites compared to 48% of participants in the treatment group, and this rate was significantly higher in the control compared to the treatment group (Fisher’s exact P = 0.030). Findings suggest the treated clothing reduced the frequency of tick exposure; however, the treated clothing did not provide 100% protection under the conditions of this study.
The researchers entered their next phase of study with a second and more recent pilot award, “Environmental impacts on effectiveness of permethrin-treated clothing used by foresters to prevent mosquito bites,” 09/30/13 – 09/29/14, funded by the Southeast Center for Agricultural Health and Injury Prevention under CDC/NIOSH Cooperative Agreement 5U54OH007547-13. The new pilot study will (1) Evaluate the effects of environmental exposure on the ability of permethrin-treated fabrics to induce mosquito knockdown and/or mortality; (2) Assess the extent to which environmental conditions (e.g., light, temperature, humidity, number of washes) impact the concentration of permethrin in treated clothing.
For more information contact:
Stephanie L. Richards, MSEH, PhD
Environmental Health Sciences Program
Department of Health Education and Promotion
College of Health and Human Performance
East Carolina University
3403 Carol Belk Building
Greenville, NC 27858