Efectividad de repelentes comerciales disponibles contra el mosquito Aedes aegypti (L ) en Yucatán, México / Effectiveness of commercial repellents against Aedes aegypti (L ) in Yucatan, México

Resumen: Objetivo: Determinar la eficacia de repelentes comerciales disponibles en Yucatán contra el mosquito Aedes aegypti, vector del dengue, Chikungunya y Zika. Material y métodos: Se determinó el tiempo de protección con base en el protocolo WHO/CTD/WHOPES/IC y la NOM-032-SSA2-2014. Resultados: Sólo el repelente con DEET (N, N-dietil-3-metilbenzamida) al 25% cumplió con la protección recomendada. La eficacia fue directamente proporcional a la concentración del DEET; aquéllos con componentes botánicos fueron poco o nada protectores. Conclusiones: Los resultados muestran que los repelentes con DEET proveen protección contra Ae. Aegypti; los repelentes botánicos, incluyendo las pulseras impregnadas, ofrecen nula protección.

Abstract: Objective: We assessed the efficacy of commercial repellents available in Yucatan against Aedes aegypti, vector of dengue, Chikungunya and Zika. Materials and methods: Protection time was determined based on WHO/CTD/ WHOPES/IC y la NOM-032-SSA2-20I4. Results: Products with DEET (N, N-diethyl-3-methylbenzamide) at 25% met the recommended protection. Efficacy was directly proportional to the concentration of DEET; botanicals repellents resulted no protective. Conclusions: Repellents with DEET provided more protection against Ae. aegypti and botanical repellents, including impregnated wristbands, provided no protection.

Efficacy of Advanced Odomos repellent cream (N, N-diethyl-benzamide) against mosquito vectors.

Background & objectives: Repellents are commonly used personal protection measures to avoid mosquito bites. In the present study, Advanced Odomos cream (12% N, N-diethyl-benzamide) was tested for its efficacy against mosquitoes in comparison to DEET (N,N-diethyl-3-methyl benzamide). Methods: Bioassays were conducted to assess the repellency of Advanced Odomos and DEET creams against Anopheles stephensi and Aedes aegypti. Their efficacy was tested on human volunteers applied with different concentrations of test creams ranging from 1 to 12 mg/cm2 and by exposing them to mosquitoes at hourly intervals. Field evaluation was also carried out to test the duration of protection of the test creams against Anopheles and Aedes mosquitoes during whole night and day time collections, respectively on human volunteers. Mosquito collections were done using torch light and aspirator. Results: Complete (100%) protection was achieved at 10 mg/cm2 cream formulation of Advanced Odomos (1.2 mg a.i/cm2) dose against An. stephensi and 12 mg/cm2 (1.44 mg a.i./cm2) against Ae. aegypti on human baits. There was no statistically significant differences in per cent protection against mosquito bites between Advanced o0 domos and DEET cream (P>0.05) in respective doses. Complete protection up to 11 h was observed against Anopheles mosquitoes during whole night collections and up to 6 h against Ae. aegypti in day time collections. No adverse reactions such as itching, irritation, vomiting, nausea, etc. were reported by the volunteers. Interpretation & conclusions: Advanced odomos cream applied at 10 mg/cm2 concentration provided 100% protection from Anopheles mosquitoes up to 11 h whereas about 6 h protection was recorded against Ae. aegypti. The laboratory and field trials indicate that for longer protection against Anopheles mosquitoes 10 mg/cm2 will be appropriate and in case of Ae. aegypti more than 10 mg/cm2 application is required for complete protection. In conclusion, the Advanced Odomos cream was comparable to the known repellent cream DEET for prolonged protection against malaria and dengue vectors.

Efficacy of repellent products against caged and free flying Anopheles stephensi mosquitoes.

The efficacy of 9 repellents (8 commercial repellents and one product under development) was evaluated on the skin at dosages of 0.65 and 1.7 mg of product/cm2, the latter dosage being the industrial standard for deet based repellents. The repellents were applied to the arm or lower leg of a human subject and tested against Anopheles stephensi in a cage or flying freely in a mosquito-proof room. In the cage tests, a product with 20% p-menthane-3, 8-diol (PMD) active ingredient provided complete repellency for 7-8 hours, while with 10% PMD had complete repellency for only 30 minutes. The natural oils of clove (Syzygium aromaticum) (10% active ingredient) plus makaen (Zanthoxylum limonella) (10% active ingredient) gave protection for 4-5 hours. In the case of free flying mosquitoes, products with 20% and 30% PMD gave complete protection for 11-12 hours at a dosage of 1.7 mg/cm2 or 6 hours at half the dosage, while the product with 10% PMD afforded protection for less than 2 hours. At the higher dosage rate 40% citronella and hydroxyethyl isobutyl piperidine carboxylate, a new synthetic compound, provided complete repellency for 7 hours. Fifty percent deet (N,N-diethyl-3-methylbenzamide) was effective for 30 hours if left undisturbed on the skin.