The transmission of 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 univers ity 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. c ruzi infection, particularly in the north of the province. This situation b rings about a high risk of appearance of congenital cases and represents an opportunity to test the most adequate strategies for detection. By applyin g systematically microhematocrit, hemoculture and PCR methods, to umbilical chord blood, an increase in the early detection of congenitally infected b abies is being achieved. In 1992-94, very high seroprevalence rates of infe ction were found among indians of the Chaco region of Salta. The overall ra te was 37%, but there were 5 localities where more than 54% of the populati on was infected. These numbers indicate that, in vast areas of the provinci al territory, fight against vector bugs must not merely consist of surveila nce activities, but rather of renewed spraying attacks. The fight must incl ude control of pregnant women and blood banks. An economic analysis of the economic return, calculated only for spraying activities and for the Depart ment of Anta (Salta), indicated a net present value of over 7 million dolla rs and an internal rate of return exceeding 60%.