Ecological aspects of South American trypanosomiasis: XIX - the domiciliation development of local triatominae populations in the Panstrongylus megistus endemic center

Abstract

The results of observations made on triatominae bug domiciliation, after house cleaning using chemicals are reported. The work was carried out in a region beloging to the Tropical Atlantic System of Eastern Brazil considered to be as the dispersal center of the Panstrongyius megistus. The observations were made during the period March 1976 to October 1978, in areas where the original bug domiciliation found before house treatment, was composed by Triatoma infestans and Panstrongylus megistus populations. After desinsectization, surveillance research and the final survey showed the development of a new but reduced and slower domiciliation process, restricted to peridomiciliary dwellings and to the P.megistus species. The dwelling infection rates were well below those initially found. After house cleaning, these values varied from 0.8 to 2.7%, as compared with 23.4% in the initial survey. This situation continued for at least two years and four months, suggesting strongly that the surveillance activities and the selective desinsectization procedure, if necessary, should be started towards the end of the third year after the general house cleaning. It is suggested that in the meantime efforts should be made to induce the local human population to co-operate in reporting new intradomiciliary triatominae foci. Participation of domiciliated or semidomiciliated vertebrates in the transferation mechanisms of trypanosomiasis infection to the home was shown to exist. These were mainly rats (Rattus) and opossums (Didelphis), of ubiquitous behaviour. In this new domiciliation process, the role of P. megistus was practically exclusive, and the appearance of Rhodnius neglectus only sporadic. The failure of T. infestans to reappear must have been due to the low mobility of the local human population. The results of the participation of P. megistus in the reinfestation showed that this latter rapidly reach the level observed for this species in the testimony area, but with no tendency to further increase.