Field evaluation of the efficacy and persistence of insect repellents DEET, IR3535, and KBR 3023 against Anopheles gambiae complex and other Afrotropical vector mosquitoes

Abstract

Synthetic insect repellents, IR3535 and KBR 3023 (also known as picaridin, or by the trade name Bayrepel, were tested in Burkina Faso against mosquito vectors of disease to compare their relative efficacy and persistence profiles to those of the 'gold standard' DEET. Collection of >49000 mosquitoes (approximately 95% belonging to the Anopheles gambiae complex) showed that after an exposure of 10h, KBR 3023 produced the highest protection against anophelines, followed by DEET, then IR3535. The response of aedines was more variable. By fitting a logistic plane model we estimated 95% effective dosages (ED95) for An. gambiae s.l., as well as a decay constant characterizing the exponential loss of repellent from the skin, with time. The ED95 values for DEET, IR3535, and KBR 3023 were 94.3, 212.4, and 81.8 microg/cm2 respectively. The decay constants were estimated at -0.241, -0.240, and -0.170 h(-1) respectively. The corresponding estimates of half-life were 2.9, 2.9, and 4.1h. Immunoenzymatic detection of the circumsporozoite protein (CSP) of Plasmodium falciparum in 842 An. gambiae s.l. showed that CSP-positive mosquitoes were equally frequent in treated and control subjects, indicating that the repellents could produce a reduction in the number of malaria infectious bites.

The burden of imported malaria in Gauteng Province

“…The majority of our patients attended public health care facilities, reflecting the appreciable burden of disease among population groups unable to afford private health care, which dispels the notion of imported malaria being confined to affluent recreational travellers. South African guidelines and community education messages encompass the basic principles of malaria prevention, namely: awareness of risk, prevention of bites through application of N,N-diethyl-3-methylbenzamide (DEET)-containing mosquito repellants, 8,9 and chemoprophylaxis when appropriate. The latter intervention is expensive and not readily available from public sector health facilities.…”

Prevention of Malaria in Long-term Travelers

“…Because picaridin has a longer halflife after application on skin, it may be particularly useful in areas with high vector densities. 33 However, the available products in the United States do not contain the optimal effective concentration and are not currently recommended for prevention of malaria. Long-term travelers also need to be aware of the biting habits of the local Anopheles populations, although this information is not readily available before travel.…”

Field evaluation of the efficacy of proprietary repellent formulations with IR3535® and Picaridin against Aedes aegypti

“…There is a number of further publications, which show the efficacy of IR3535 ® against a variety of arthropods (Buescher et al 1982;Costantini et al 2004;Marchio 1996;Milutinovic et al 2000Milutinovic et al , 2002Peters et al 2002;WHOPES 2000), including a recent one, which showed the efficacy of IR3535 ® against Phlebotomus (Naucke et al 2006). …”