Chagas disease in northern Chile: Detection of Trypanosoma cruzi in children, dogs and triatomine bugs.

Chagas disease is an anthropozoonotic disease caused by the protozoan Trypanosoma cruzi, transmitted by triatomine vectors. In Chile, there are four species of triatomine bugs that are potential vectors of T. cruzi, being Triatoma infestans the main vector in endemic areas of the country. The "Programa Nacional de Control Vectorial de la Enfermedad de Chagas de Chile" has significantly reduced the rates of home infestation to less than 1% and has interrupted vectorial transmission since 1999. The objective of this study was to evaluate the impact of vectorial control and the continuity of the interruption of vectorial transmission in northern Chile (provincia de El Loa, región de Antofagasta). The study comprised fingerstick blood samples of 2104 children, attending local school, venous blood samples of 65 dogs, associated to houses with T. infestans unique findings and vector infestation, and intestine samples of 284 T. infestans specimens, from the provincia de El Loa, during 2014-2016 period. The samples were analyzed by enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence and/or polymerase chain reaction (PCR) techniques. A total of 5 children (0.24%), 7 dogs (10.8%), and 6 specimens of T. infestans (2.1%) resulted positive to T. cruzi infection. This study showed that the risk of transmission of Chagas disease is low in the north of Chile (provincia de El Loa), detected a low positive rate of chagasic children and of infected triatomine bugs, and showed the existence of T. cruzi transmission in dogs, which are used as natural sentinels for the detection of T. cruzi infection, being especially useful during surveillance program in human population characterized by low seroprevalence.

Modeling the Potential Distribution of the Malaria Vector Anopheles (Ano.) pseudopunctipennis Theobald (Diptera: Culicidae) in Arid Regions of Northern Chile.

The extreme north of Chile presents a subtropical climate permissive of the establishment of potential disease vectors. Anopheles (Ano.) pseudopunctipennis is distributed from the south of the United States to the north of Argentina and Chile, and is one of the main vectors of malaria in Latin America. Malaria was eradicated from Chile in 1945. Nevertheless, the vector persists in river ravines of the Arica and Tarapacá regions. The principal effect of climate change in the north of Chile is temperature increase. Precipitation prediction is not accurate for this region because records were erratic during the last century. The objective of this study was to estimate the current and the projected distribution pattern of this species in Chile, given the potential impact due to climate change. We compiled distributional data for An. (Ano.) pseudopunctipennis and constructed species distribution models to predict the spatial distribution of this species using the MaxEnt algorithm with current and RCP 4.5 and 8.5 scenarios, using environmental and topographic layers. Our models estimated that the current expected range of An. (Ano.) pseudopunctipennis extends continuously from Arica to the north of Antofagasta region. Furthermore, the RCP 4.5 and 8.5 projected scenarios suggested that the range of distribution of An. (Ano.) pseudopunctipennis may increase in longitude, latitude, and altitude limits, enhancing the local extension area by 38 and 101%, respectively, and local presence probability (>0.7), from the northern limit in Arica y Parinacota region (18°S) to the northern Antofagasta region (23°S). This study contributes to geographic and ecologic knowledge about this species in Chile, as it represents the first local study of An. (Ano.) pseudopunctipennis. The information generated in this study can be used to inform decision making regarding vector control and surveillance programs of Latin America. These kinds of studies are very relevant to generate human, animal, and environmental health knowledge contributing to the "One Health" concept.