Chagas disease in the subandean valleys of northwest Argentina: epidemiological role of two triatomine species and cavies.

CECERE MC; CARDINAL MV; LEPORACE MARINA; FERNANDEZ M.PILAR; ARRABAL JP; MORENO CLAUDIO; GURTLER RICARDO E

Congreso; X Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2014

Wild and synanthropic rodent species are implicated in the transmission of Trypanosoma cruzi in several regions where TcI is the most prevalent Discrete Typing Unit (DTU) detected. In Argentina, several rodent species of Sigmodontinae were infected with Tc while species of Caviinae (include ?cuises? or guinea pigs) have received less attention. Regarding Triatoma eratyrusiformis (Te), its epidemiological relevance has not been assessed although it has a wider geographic distribution in western Argentina associated with edentate and rodents. As part of a wider research project on Chagas disease vector control, the present study sought to understand the role of cavies and two peridomestic triatomine species in a well-defined rural area of Tafi del Valle (Tucumán). The occurrence of T. cruzi infection in Microcavia australis and its reservoir host competence were assessed by xenodiagnosis and by polymerase chain reaction amplification of the hyper-variable region of kinetoplast DNA minicircles of T. cruzi (kDNA-PCR) from blood samples. For assessing host-vector contact across different ecotopes, bloodmeal contents in Te and Triatoma infestans (Ti) were tested with a direct ELISA assay against human, dog, cat, chicken, pig, goat, cavy, rabbit and murid rodent (rat or mouse) antisera. Bug infection by T. cruzi was evaluated by optical microscopy or kDNA-PCR. The DTUs of T. cruzi infection in cavies, domestic animals and triatomine bugs were identified from fecal or rectal ampoule samples. Cavies presented a very high prevalence of infection (46.3%) and TcI was the only DTU identified. The infectiousness to Ti of cavies positive by xenodiagnosis or kDNA-PCR was very high (mean, 55.8%; 95% CI = 48.4-63.1%) and exceeded 80% in 44% of the individuals. The host-feeding patterns were spatially structured according to habitat type and correlated closely with the main resident host(s). The main bloodmeal sources for Te collected from fences and corrals was cavy (95%) followed by rat and pig. Ti fed on chicken (57%), goat, human, rabbit and less frequently on dog, cavy and pig. In domiciles, the main bloodmeal sources of Ti were humans (60%) followed by chickens and dogs. Most Te and Ti had unmixed blood meals (85-88%). T. cruzi infecction in bugs was greater in peridomiciles (53%, 79/149) than in domiciles (43%, 13/30). In peridomiciles, bug infection reached 81%in Te and 18% in Ti. TcVI was identified in one Te captured in a corral and in one cat, and TcI in another Te from fences and in Ti from corral, piled material, and fence. The novel finding of T. cruzi-infected M. australis cavies thriving in bug-infested habitats close to human dwellings represents a new scenario of TcI transmission in Argentina. Chemical control and environmental management measures directed to peridomestic habitats, especially to the dry-shrub fences, may be needed for improved vector control of Ti and other secondary vectors.