These results illustrate Zika virus risk at the global level and provide maps to target the prevention and control measures especially in areas with higher risk, in countries with less sanitation and poorer resources. Many countries without previous vector reports could become active transmission zones in the future, so vector surveillance should be implemented or reinforced in these areas.

Chagas disease, caused by the protozoan Trypanosoma cruzi and transmitted by triatomine insect vectors, affects about 10 million people worldwide (Schmunis 2000) and is the third most important global parasitic disease after malaria and schistosomiasis (World Bank 1993). Because of effective vector control campaigns, the number of acute cases has decreased markedly and has been reduced to nearly zero in previously highly endemic areas of Uruguay, Chile and Brazil (Schofield et al. 2006).The Chagas disease vector Triatoma infestans (Klug 1834) was historically considered an e�clusively do-) was historically considered an e�clusively domestic insect, but it has now been reported in sylvan environments (Noireau et al. 2005, Noireau 2009). The first sylvatic population of T. infestans was reported in Cochabamba, Bolivia, inhabiting rock piles associated with wild guinea pigs (Torrico 1946). Other reports have shown T. infestans in Argentina (Mazza & Schreiber 1938, Mazza 1943, Ceballos et al. 2009), Paraguay (Velasquez & González 1959 and Brazil (Barretto et al. 1963) under rocks or trunks of fallen trees, in hollow trees, under bark, in shelters or burrows of marsupials and rodents and in bird nests occupied by owls, parrots or small rodents (Noireau et al. 1997). Wild T. infestans has been found in an e�tended geographical region throughout Chaco and three Andean departments of Bolivia: Cochabamba, La Paz and Potosí (Noireau et al. 1999, Cortez et al. 2007. T. infestans was considered to be eradicable due to its strictly domestic behavior and its non-autochthonous status outside of its apparent centre of origin in the Andean valleys of Bolivia. This theory has been challenged by empirical evidence of wild individuals collected by vector control programs and researchers over several decades (Gürtler 2009). Sylvatic triatomines may occasionally invade human residences, acting as founders of new colonies (Fitzpatrick et al. 2008). Hence, it is necessary to study the ecology and behavior of their populations to understand the domiciliation process and generate new strategies for their control (Beard et al. 2002, Guhl et al. 2009, Moncayo & Silveira 2009).In Chile, parasite transmission from vectors to humans occurs mainly in rural and suburban areas encompassing the northern desert and semiarid and Mediterranean environments, between latitudes 18°30'S and 34°36'S. The triatomine insects T. infestans, Mepraia spinolai (Porter 1934) and Mepraia gajardoi are the vector species that have been reported in that area (Spinola 1852, Neghme 1982, Lent et al. 1994, Frias et al. 1998.In 1991, several countries of South America, including Chile, established the Southern Cone Initiative for control of Chagas disease (INCOSUR-Chagas), which provided united strategy, control actions and an information system used to evaluate local control programs (Silveira 2002). The specific aims of the initiative were the following: (i) the elimination of T. infestans from dwellings and their surroundings in endemic areas, (ii) the reduction an...

The finding of T infestans in a wild habitat is noticeable. This is the first report of such phenomenon in Chile. The high infection rates with T cruzi, explains the maintenance of Chagas disease wild cycle in Chile.

Background Mepraia gajardoi and Mepraia spinolai are endemic triatomine vector species of Trypanosoma cruzi, a parasite that causes Chagas disease. These vectors inhabit arid, semiarid and Mediterranean areas of Chile. Mepraia gajardoi occurs from 18° to 25°S, and M. spinolai from 26° to 34°S. Even though both species are involved in T. cruzi transmission in the Pacific side of the Southern Cone of South America, no study has modelled their distributions at a regional scale. Therefore, the aim of this study is to estimate the potential geographical distribution of M. spinolai and M. gajardoi under current and future climate scenarios. Methods We used the Maxent algorithm to model the ecological niche of M. spinolai and M. gajardoi, estimating their potential distributions from current climate information and projecting their distributions to future climatic conditions under representative concentration pathways (RCP) 2.6, 4.5, 6.0 and 8.5 scenarios. Future predictions of suitability were constructed considering both higher and lower public health risk situations. Results The current potential distributions of both species were broader than their known ranges. For both species, climate change projections for 2070 in RCP 2.6, 4.5, 6.0 and 8.5 scenarios showed different results depending on the methodology used. The higher risk situation showed new suitable areas, but the lower risk situation modelled a net reduction in the future potential distribution areas of M. spinolai and M. gajardoi. Conclusions The suitable areas for both species may be greater than currently known, generating new challenges in terms of vector control and prevention. Under future climate conditions, these species could modify their potential geographical range. Preventive measures to avoid accidental human vectorial transmission by wild vectors of T. cruzi become critical considering the uncertainty of future suitable areas projected in this study.

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Zika virus (ZIKV) is an arbovirus transmitted mainly by Aedes aegypti mosquitoes. Recent scientific evidence on Culex quinquefasciatus has suggested its potential as a vector for ZIKV, which may change the current risk zones. We aimed to quantify the world population potentially exposed to ZIKV in a spatially explicit way, considering the primary vector (A. aegypti) and the potential vector (C. quinquefasciatus). Our model combined species distribution modelling of mosquito species with spatially explicit human population data to estimate ZIKV exposure risk. We estimated the potential global distribution of C. quinquefasciatus and estimated its potential interaction zones with A. aegypti. Then we evaluated the risk zones for ZIKV considering both vectors. Finally, we quantified and compared the people under risk associated with each vector by risk level, country and continent. We found that C. quinquefasciatus had a more temperate distribution until 42° in both hemispheres, while the risk involving A. aegypti is concentrated mainly in tropical latitudes until 35° in both hemispheres. Globally, 4.2 billion people are under risk associated with ZIKV. Around 2.6 billon people are under very high risk associated with C. quinquefasciatus and 1 billion people associated with A. aegypti. Several countries could be exposed to ZIKV, which emphasises the need to clarify the competence of C. quinquefasciatus as a potential vector as soon as possible. The models presented here represent a tool for risk management, public health planning, mosquito control and preventive actions, especially to focus efforts on the most affected areas.

Background Trypanosoma cruzi is a protozoan parasite that is transmitted by triatomine vectors to mammals. It is classified in six discrete typing units (DTUs). In Chile, domestic vectorial transmission has been interrupted; however, the parasite is maintained in non-domestic foci. The aim of this study was to describe T . cruzi infection and DTU composition in mammals and triatomines from several non-domestic populations of North-Central Chile and to evaluate their spatio-temporal variations. Methodology/Principal findings A total of 710 small mammals and 1140 triatomines captured in six localities during two study periods (summer/winter) of the same year were analyzed by conventional PCR to detect kDNA of T . cruzi . Positive samples were DNA blotted and hybridized with specific probes for detection of DTUs TcI, TcII, TcV, and TcVI. Infection status was modeled, and cluster analysis was performed in each locality. We detected 30.1% of overall infection in small mammals and 34.1% in triatomines, with higher rates in synanthropic mammals and in M . spinolai . We identified infecting DTUs in 45 mammals and 110 triatomines, present more commonly as single infections; the most frequent DTU detected was TcI. Differences in infection rates among species, localities and study periods were detected in small mammals, and between triatomine species; temporally, infection presented opposite patterns between mammals and triatomines. Infection clustering was frequent in vectors, and one locality exhibited half of the 21 clusters found. Conclusions/Significance We determined T . cruzi infection in natural host and vector populations simultaneously in a spatially widespread manner during two study periods. All captured species presented T . cruzi infection, showing spatial and temporal variations. Trypanosoma cruzi distribution can be clustered in space and time. These clusters may represent different spatial and temporal risks of transmission.

BackgroundChagas disease is caused by the protozoan Trypanosoma cruzi, which is transmitted to mammal hosts by triatomine insect vectors. The goal of this study was to model the spatial distribution of triatomine species in an endemic area.MethodsVector’s locations were obtained with a rural householders’ survey. This information was combined with environmental data obtained from remote sensors, land use maps and topographic SRTM data, using the machine learning algorithm Random Forests to model species distribution. We analysed the combination of variables on three scales: 10 km, 5 km and 2.5 km cell size grids.ResultsThe best estimation, explaining 46.2% of the triatomines spatial distribution, was obtained for 5 km of spatial resolution. Presence probability distribution increases from central Chile towards the north, tending to cover the central-coastal region and avoiding areas of the Andes range.ConclusionsThe methodology presented here was useful to model the distribution of triatomines in an endemic area; it is best explained using 5 km of spatial resolution, and their presence increases in the northern part of the study area. This study’s methodology can be replicated in other countries with Chagas disease or other vectorial transmitted diseases, and be used to locate high risk areas and to optimize resource allocation, for prevention and control of vectorial diseases.