CM. Chagas Disease in Mérida State-Venezuela: Presence of Triatomine Bug Species and Potential Risk of Trypanosoma cruzi Transmission without Indoor Colonization.

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ABSTRACT

We investigated the role of visitor triatomine-bugs inside houses, without indoor colonization, as well as its potential role in Trypanosoma cruzi transmission to humans, and the epidemiological significance for Chagas disease occurrence in the study area. The research was carried out during the period 2012-2018 in different localities of Mérida state in the Andean region of western Venezuela, where Chagas disease is endemic. The approach consisted of sampling Triatomine-bugs, species identification, individual dissection, and detection of T. cruzi-infection. In addition, we included individuals involved in Chagas disease’s specific cases, micro epidemic outbreaks, or living in risky localities. Human samples consisted of peripheral blood examination using a combination of parasitologic, serologic, and molecular (PCR) tests. Adult-specimens of T. cruzi-infected Rhodnius prolixus, Rhodnius pictipes, Panstrongylus geniculatus, and Eratyrus mucronatus were collected from well-structured houses located in rural and urban areas of Mérida-Venezuela. Although most infected-bugs were captured indoors, showing metacyclic-heavy load in rectal ampules, no-sign of domestic colonization was evidenced at any time. The use of different techniques to examine the human blood samples indicated 47.6% positives for parasitological methods, and all the infected people showed anti-T. cruzi antibodies by serological tests and the PCR assay corroborated infection of 42,8% of the patients. In conclusion, T. cruzi-infected, intruder specimens, that reached homes from peridomestic or sylvatic environments were responsible for Chagas disease outbreaks. Our results contradict previous assertions that T. cruzi-transmission is only relevant in existing domiciliated vectors. The potential epidemiological significance of T. cruzi-infected visiting bugs on the occurrence of Chagas disease outbreaks, without indoor colonization, makes it mandatory to design new strategies to fight visiting-triatomine vectors and predict, prevent and control Chagas disease in indoor-bug free houses

Key Words: Chagas disease; T. cruzi-infected visiting bugs; Bug-free house; Transmission

Rafael Rangel-Aldao, Editor

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