Identification of a hyperendemic area for Trypanosoma cruzi infection in central Veracruz, Mexico

Abstract

The state of Veracruz, Mexico, is a well-recognized endemic region for Chagas disease, but the geographic distribution of the disease and its magnitude are still poorly documented. We evaluated the seroprevalence of Trypanosoma cruzi infection in the sanitary jurisdictions of Cordoba and Cosamaloapan in central Veracruz. A total of 654 serum samples from 19 rural localities were tested by using four tests: two enzyme-linked immunosorbent assays, an indirect immunofluorescent, and Western blotting. Overall, 110 (16.8%) of 654 samples were positive for T. cruzi by >/= 2 tests (95% confidence interval = 14.2-19.9%). The municipality of Tezonapa in the jurisdiction of Cordoba was identified as a potential hyperendemic region with seroprevalence rates </= 45% in young children. No cases were detected in the jurisdiction of Cosamaloapan. Further studies should help clarify T. cruzi transmission dynamics in Tezonapa. The magnitude of T. cruzi infection rate in this region calls for the urgent implementation of extensive epidemiologic surveillance and control programs.

Figure 1.

Mexico (bottom left), the state of Veracruz (center), and the study area (inset). White area corresponds to the state of Veracruz, light gray to the state of Oaxaca, and dark gray to the state of Puebla, with lines delimitating the respective municipalities, including Amatlan, Tezonapa, and Tierra Blanca. Black circles indicate the position of the indicated villages.

Figure 2.

Geographic distribution of Trypanosoma cruzi infection in central Veracruz, Mexico. Circles are proportional to the number of serum samples analyzed in each village as indicated on the bottom right scale. Red areas in the pie charts represent the proportion of T. cruzi-seropositive patients, which is also indicated for villages with seropositive patients. Background image shows a satellite image of the area with blues lines indicating rivers and yellow lines indicating boundaries of the municipalities. This figure appears in color at www.ajtmh.org.

Figure 3.

Distribution of Trypanosoma cruzi infection in Tezonapa, Mexico by age groups. The population was stratified according to the indicated age groups and infection rates are shown as mean ± 95% confidence interval. Numbers on the top of the error bars refer to the number of samples for each group. Seroprevalence rates were significantly associated with age (r² = 0.915, P = 0.004, by second-order polynomial regression), as indicated by the regression line and its 95% confidence area (dotted lines).