Prevention and Control

The goal of any prevention or control program is to reduce contact between humans and kissing bugs in order to prevent discomfort from bites and the more serious problem of Chagas disease. Control of Chagas disease involves the use of insecticides, improving housing conditions, and treating blood used for transfusions to kill the trypanosome. Residual insecticides sprayed on houses or applied to walls in paints are effective in controlling triatomines. However, long-term control requires careful surveillance and selective applications of insecticides. Some simple surveillance techniques, such as placing pieces of colored paper on the inside walls of houses, have been very successful in assessing the presence of triatomines. Their fecal patterns on the paper provide an indicator of triatomine activity. Houses treated with insecticides subsequentiy may be colonized by peridomestic or sylvatic species.

Defecation by Triatoma infestans and R. prolixus soon after feeding is dependent upon full engorgement by the bugs which, in turn, appears to be related to the density of the bug population in a given habitat; the greatest chance of engorgement is at low-density populations. Presumably, high bug densities with constant host resources lead to smaller blood meal sizes and a slower rate of defecation. Therefore, the chance of inhabitants becoming infected with Trypanosoma cruzi tends to be greatest in newly colonized houses where the bug population is rising or in houses being repopulated after vector control has been instituted.

Long-term control of triatomine bugs is best achieved in houses in which rough walls have been covered with plaster, thatch roofs have been replaced with tin or tile, and mud floors have been replaced with concrete. Such changes in construction, as well as the removal of wall hangings, firewood, and accumulated debris or vegetation, which serve as hiding places for triatomines, help to reduce the size of bug populations.

The drugs available for the treatment of acute Chagas disease, such as nifurtimox and benznidazole, are reasonably effective in preventing the development of chronic disease. However, they are associated with a high frequency of side effects, and neither is known to affect the course of chronic Chagas disease once it develops. Gentian violet effectively decontaminates donor blood, but routine screening and treatment of the blood supply is necessary to prevent transmission of T. cruzi via blood donors in endemic areas.

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