Anti-triatomine saliva immunoassays for the evaluation of impregnated netting trials against Chagas disease transmission

Abstract

Insecticide-impregnated nets can kill triatomine bugs, but it remains unclear whether they can protect against Chagas disease transmission. In a field trial in Quequeña, Peru, sentinel guinea pigs placed in intervention enclosures covered by deltamethrin-treated nets showed significantly lower antibody responses to saliva of Triatoma infestans compared with animals placed in pre-existing control enclosures. Our results strongly suggest that insecticide-treated nets prevent triatomine bites and can thereby protect against infection with Trypanosoma cruzi. Anti-salivary immunoassays are powerful new tools to evaluate intervention strategies against Chagas disease.

Fig. 1

Photograph of a newly constructed guinea pig corral with an impregnated net and an original corral. Groups of sentinel guinea pigs were either placed in newly constructed guinea pig corrals which were covered with deltamethrin-impregnated nets, or pre-existing guinea pig pens (pictured behind the newly constructed pen).

Fig. 2

Triatoma infestans infestation of guinea pig corrals in 10 households of Quequeñe, Peru. Households were sprayed with insecticides by the Arequipa Regional Ministry of Health in December 2006 and trained personal searched the entire households for triatomines for 1 h. All adult insects and second through the fifth instars were examined for the presence of Trypanosoma cruzi from all captured T. infestans (gray bars) in the guinea pig corrals. The black and white bars indicate the total numbers of T. cruzi-infected and non-infected bugs, respectively.

Fig. 3

Antibody responses of sentinel guinea pigs to salivary proteins of Triatoma infestans. Sentinel guinea pigs were either placed in original corrals (A, squares) or corrals with deltamethrin-impregnated nets (B, circles) of 10 households in the town of, Peru, in June 2006. Three months later the antibody response of guinea pigs to T. infestans saliva was measured by ELISA. The final O.D._492nm was determined by calculating the mean O.D._492nm of the duplicate wells of each guinea pig serum and subtracting the O.D._492nm of the mean O.D._492nm of the negative control sera per household.