[The impact of curtains impregnated with deltamethrin on the vectors and morbidity of malaria: results in Ankazobe, on the plateaus of Madagascar].

To evaluate the efficacy of deltamethrin impregnated curtains on malaria morbidity in a low transmission area, we studied volunteer families in the village of Ankazobe in the Madagascar Highlands from February 1993 to June 1994. After randomization, we provided 46 houses having 244 inhabitants with impregnated curtains (I) and 45 others having 257 inhabitants with nonimpregnated curtains (NI) as controls. We first estimated the number of mosquito bites in the protected versus nonprotected households. Every month, we captured mosquitos on humans in 6 houses per night for 4 nights. For the I group compared to the NI group, the number of bites by the Anopheles funestus vector per human per night was reduced by 64% in 1993 and 39% in 1994. We also analyzed the malaria morbidity. Malaria morbidity was defined as patients having both temperatures greater than 37.5 degrees C and Plasmodium falciparum parasitemia greater than 1500/microliter with clinical symptoms. From February to July 1993, we observed no significant difference in morbidity: there were 103 cases of malaria among 244 inhabitants of the I group and 117 cases among 257 inhabitants of the NI group. However, during the period of highest transmission from March to May in 1993, there were significantly fewer cases in the I group (68) than in the NI group (94). From January to June 1994, the difference was clear: only 35 malaria cases were observed among the 208 inhabitants of the I group as compared to 65 cases among the 223 inhabitants of the NI group (Chi square = 9.17, p = 0.0024). Inhabitants of the I group could have been contaminated before the curtains were set up. After treatment of the cases and use of curtains during the second year, we observed a reduction in the number of mosquito bites and malaria cases. The small size of the trial made the interpretation of the data difficult. Nonetheless, the results tentatively support the use of impregnated curtains as an antimalaria tool in an integrated control program.