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.

House Infestation Dynamics and Feeding Sources of Triatoma dimidiata in Central Veracruz, Mexico

“…6 Indeed, our data indicate a higher abundance of bugs inside the domiciles in the municipality of Tezonapa compared with Tierra Blanca, suggesting a higher risk in the former, which coincides very well with the higher seroprevalence observed in Tezonapa and the lower seroprevalence in Tierra Blanca. 6 These discrepancies between the two municipalities may be related to differences in ecological conditions as suggested before, 6 because villages in Tezonapa valley are surrounded by dry soil of open fields for agriculture, with large and numerous patches of evergreen tropical forest, whereas in the coastal plain of Tierra Blanca the soil is humid and almost exclusively covered by fields and pasture. Alternatively, there might be differences in housing structure and conditions between the municipalities that could also contribute to differences in triatomine infestation.…”

“…6 We thus evaluated here the dynamics of house infestation by T. dimidiata in central Veracruz, as well as its feeding sources, to provide key data on T. cruzi transmission dynamics and potential vector control interventions.…”

“…However, we also recently identified an area of very high seroprevalence against Trypanosoma cruzi in central Veracruz, in an area that may have been overlooked in previous works, suggesting that more extensive studies are needed to fully characterize the extent of Chagas disease in the region and its transmission dynamics to humans. 6 The only vector species reported so far in Veracruz is Triatoma dimidiata, which showed relatively low infestation and infection indexes (10.9% and 9.0%, respectively), but a high colonization index (50.0%). 5 These data confirmed an important entomological risk of T. cruzi transmission in most parts of the state.…”

“…23 The abundant feeding on humans inside the domiciles also confirms the high risk of T. cruzi transmission, in agreement with the elevated seroprevalence observed in the area. 6 On the other hand, the feeding on several domestic animals suggests that these may play a role as risk factors for house infestation and T. cruzi transmission. Further studies on the determinants for house infestation should help clarify this point.…”

High Frequency of Human Blood in Triatoma dimidiata Captured Inside Dwellings in a Rural Community in the Yucatan Peninsula, Mexico, but Low Antibody Seroprevalence and Electrocardiographic Findings Compatible with Chagas Disease in Humans

“…16,25 Exceptionally high seroprevalence is observed in some areas of Veracruz, where it can reach up to 16.8%. 26 For the Yucatan peninsula, there is no available update on the seroprevalence surveys in rural communities, although seroprevalence in urban blood donors indicates low human infection between 0.7% in the Yucatan State and 0.5% in Campeche State. 27,28 There are several possible explanations for this low transmission of T. cruzi despite the high infestation index reached in some months of the year, high contact with triatomines's bite, and relatively moderate natural infection of triatomines.…”