Research
A low-cost repellent for malaria vectors in the Americas: results of two field trials in Guatemala and Peru
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* Corresponding author: Samuel T Darling darlingi@telus.net
1 Ifakara Health Research and Development Center, Ifakara, Tanzania
2 Puerta del Cielo Foundation, Canada/ Guatemala
3 Ministerio de Salud, Iquitos, Peru
4 Universidad del Valle, Guatemala City, Guatemala
5 Rothamsted Research, Harpenden, UK
Malaria Journal 2007, 6:101 doi:10.1186/1475-2875-6-101
Published: 1 August 2007Abstract
Background
The cost of mosquito repellents in Latin America has discouraged their wider use among the poor. To address this problem, a low-cost repellent was developed that reduces the level of expensive repellent actives by combining them with inexpensive fixatives that appear to slow repellent evaporation. The chosen actives were a mixture of para-menthane-diol (PMD) and lemongrass oil (LG).
Methods
To test the efficacy of the repellent, field trials were staged in Guatemala and Peru. Repellent efficacy was determined by human-landing catches on volunteers who wore the experimental repellents, control, or 15% DEET. The studies were conducted using a balanced Latin Square design with volunteers, treatments, and locations rotated each night.
Results
In Guatemala, collections were performed for two hours, commencing three hours after repellent application. The repellent provided >98% protection for five hours after application, with a biting pressure of >100 landings per person/hour. The 15% DEET control provided lower protection at 92% (p < 0.0001). In Peru, collections were performed for four hours, commencing two hours after repellent application. The PMD/LG repellent provided 95% protection for six hours after application with a biting pressure of >46 landings per person/hour. The 20% DEET control provided significantly lower protection at 64% (p < 0.0001).
Conclusion
In both locations, the PMD/LG repellent provided excellent protection up to six hours after application against a wide range of disease vectors including Anopheles darlingi. The addition of fixatives to the repellent extended its longevity while enhancing efficacy and significantly reducing its cost to malaria-endemic communities.