Chagas disease in a domestic transmission cycle in Southern Texas, USA - Dispatches

Emerging Infectious Diseases, Jan, 2003 by Charles B. Beard, Greg Pye, Frank J. Steurer, Ray Rodriguez, Richard Campman, A. Townsend Peterson, Janine Ramsey, Robert A. Wirtz, Laura E. Robinson

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Conclusions

Triatoma gerstaeckeri is considered a sylvatic species, most frequently associated with pack rat (Neotoma spp.) burrows (4). Although individual triatomine insects occasionally invade domestic dwellings throughout the southwestern United States and Mexico (4,5,14), this species has not been reported to colonize these habitats. In this investigation, colonization appears to have occurred, based on the observation of large numbers of bugs, including ones in immature stages. In the Chagas disease-endemic regions of South and Central America, the primary risk for insect transmission to humans is related to the efficiency with which local vector species can invade and colonize homes, resulting in a domestic transmission cycle for what is otherwise exclusively a zoonotic disease in the southern United States. In disease-endemic countries, higher house infestation rates generally result in a higher risk of transmission. At the first site in south Texas, six dogs either died or tested positive for T. cruzi, and 24 of 31 bugs contained hindgut trypanosomes. These observations demonstrate the existence of a domestic transmission cycle for an insect species that is typically considered a zoonotic vector. Whether this observation represents an isolated case or actually occurs more frequently but remains unrecognized, indicating an emerging public health problem, remains to be determined. The serologic results in stray dogs are very similar to those reported in previous studies from the region, suggesting that the disease is stably maintained in this reservoir host (15,16). The distributional predictions based on GARP models indicate a potentially broad distribution for this species and suggest additional areas of risk beyond those previously reported (14), should this problem become of greater public health concern.

References

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(6.) Camargo M. 1969. Cross-reactivity in fluorescence tests for Trypanosoma and Leishmania antibodies. Am J Trop Med Hyg 1969; 18:500-5.