[The transmission de Chagas disease in Salta and the detection of congenital cases].

Data on the prevalence of Trypanosoma cruzi infection is presented for the province of Salta, Argentina. Special emphasis is given to the detection of congenital transmission and to the economic benefits of preventing Chagas' disease. Seroepidemiological data obtained from 20 year old army draftees revealed a reduction, from 22.7 to 11.11% between 1964 and 1985. In university students, a rate of 0.96% was found in 1998. Surveys carried out during 1996 showed that more than 15% of the pregnant women analyzed carried T. cruzi infection, particularly in the north of the province. This situation brings about a high risk of appearance of congenital cases and represents an opportunity to test the most adequate strategies for detection. By applying systematically microhematocrit, hemoculture and PCR methods, to umbilical chord blood, an increase in the early detection of congenitally infected babies is being achieved. In 1992-94, very high seroprevalence rates of infection were found among indians of the Chaco region of Salta. The overall rate was 37%, but there were 5 localities where more than 54% of the population was infected. These numbers indicate that, in vast areas of the provincial territory, fight against vector bugs must not merely consist of surveilance activities, but rather of renewed spraying attacks. The fight must include control of pregnant women and blood banks. An economic analysis of the economic return, calculated only for spraying activities and for the Department of Anta (Salta), indicated a net present value of over 7 million dollars and an internal rate of return exceeding 60%.