Epidemiología de la enfermedad de Chagas en Chile: seguimiento serológico de 1.906 habitantes de un área rural endémica de la IV región, 1991-1993 / Epidemiology of Chagas' disease in Chile: serological follow-up of 1.906 inhabitants from an endemic rural area in IV región, 1991-1993

ABSTRACT

The IV region (29º 30' -32º 13' south lat.) is located in the center of the geographical area of distribution of Chagas' disease in Chile. Triatoma infestans is the main and almost exclusive vector of trypanpsoma cruzi in this country. The mean prevalence rate of T. cruzi human infection in urban and periurban sections of IV region is 24,7 percent. To assess the impact of anti-T. infestans activities, by means of health education and sprayings of dwellings with insecticides, carried out in the IV Region since 1980, during january-february (summer) a serological follow-up to residents from 46 rural chagasic localities was performed. An indirect hemagglutination test and an indirect immunofluorescence test were done to each of the surveyed persons. In 1991, 303 (15.9 percent) out of 1,906 examined people resulted serologically positive. In 1992, previous discarding the positive individuals found in 1991. 1,334 persons were examined resulting positive 9 (0.7 percent). In 1993, 1,398 persons were surveyed and 26 (1.9 percent) were positive. It is neteworthy that none of these 35 positive persons had been surveyed in 1991, being difficult to assert if any was positive before. Two infants, daughters of positive mothers, serologically positive at the beginning, changed to negative in the following survey, indicatins that it was passive transfer of maternal specific antibodies. According to the results of this study, it is concluded that dwelling spraying with persistent-activity insecticides against T. infestans and health education are good tools in the control of T. cruzi human infection, particularly when the involved community participates