62 - Evaluation of the efficacy of 20% IR3535® with a sustained‑release formulation and 25%DEET insect repellents against mosquitoes in a field setting in Ghana

Abstract: Background
Personal protection with topical skin repellents has been advocated for use against vector-borne dis‑

eases. This study compared the efficacies of a 20% ­ IR3535® lotion with Staytec technology formulation and 25% DEET

lotion in repelling mosquitoes in two rural communities in Ghana.

Methods
Mosquito biting densities were established at baseline and during the intervention using human landing

collections (HLC). These were carried out overnight from 21:00–06:00 Greenwich Mean Time (GMT). Prior to the HLC,

the exposed legs were treated with either a lotion of the 20% ­ IR3535® or 25% DEET (as test) at a rate of 1 g/600 ­ cm2,

and 70% ethanol (as control). The sampling (HLC) was performed using the Latin square design. Mosquito species

were identified morphologically using some identification keys and molecularly using polymerase chain reaction (PCR). Evaluations

were carried out to determine the knock down resistant (kdr) allele frequencies. The presence of Plasmodium falcipa-

rum circumsporozoite proteins was identified using immunological method.

Results
The major malaria vector observed in the study area was Anopheles gambiae sensu lato (s.l.) with high frequencies

of kdr-west mutation in the population. The 20% ­ IR3535® and 25% DEET treatments reduced mosquito bites by 98%

and 95%, respectively, compared with the control (P < 0.01). The collectors were protected by the 20% ­ IR3535®

and 25% DEET for about 92% and 89% of the time, respectively. There was also a sustained protection of the two

repellents for 9 h. This protection prevented infectious bites in the treatment group compared with the control.

Conclusions
The 20% ­ IR3535® with Staytec technology can provide significant protection against Anopheles

and other mosquito bites and will be useful for complementing other vector control interventions.

Keywords IR3535®, Repellent, DEET, Anopheles gambiae s.l., Repellency, Ghana