Vector control strategies against indigenous species is not easy, due to their capacity to reinvade treated premises from sylvatic ecotopes. Between August 1996 and December 1997 we conducted a study on reinfestation of houses after spraying in a county

Reports of triatomine infestation in urban areas have increased. We analysed the spatial distribution of infestation by triatomines in the urban area of Diamantina, in the state of Minas Gerais, Brazil. Triatomines were obtained by community-based entomological surveillance. Spatial patterns of infestation were analysed by Ripley’s K function and Kernel density estimator. Normalised difference vegetation index (NDVI) and land cover derived from satellite imagery were compared between infested and uninfested areas. A total of 140 adults of four species were captured (100 Triatoma vitticeps, 25Panstrongylus geniculatus, 8 Panstrongylus megistus, and 7 Triatoma arthurneivai specimens). In total, 87.9% were captured within domiciles. Infection by trypanosomes was observed in 19.6% of 107 examined insects. The spatial distributions ofT. vitticeps, P. geniculatus, T. arthurneivai, and trypanosome-positive triatomines were clustered, occurring mainly in peripheral areas. NDVI values were statistically higher in areas infested by T. vitticeps and P. geniculatus. Buildings infested by these species were located closer to open fields, whereas infestations of P. megistus andT. arthurneivai were closer to bare soil. Human occupation and modification of natural areas may be involved in triatomine invasion, exposing the population to these vectors.

This study aimed to analyse the spatial distribution of human (2007-2013) and canine (2013) visceral leishmaniasis (VL) in the city of Araçuaí, Minas Gerais, Brazil, and identify the socio-environmental factors related to their occurrence. The spatial distribution of human and canine cases was analysed by kernel density estimation (KDE) and the K function. The KDE values were analysed for correlation between human and canine LV and for normalised difference vegetation index (NDVI). Socio-environmental aspects of household structures and surroundings were evaluated. The spatial distribution of human and canine VL cases exhibited a significant aggregated pattern in distances greater than 350 and 75 m, respectively. The higher occurrence of human and canine infection occurred in the central area of the city. A positive correlation between the densities of human and canine cases was observed, as well as a negative correlation between NDVI and densities of human and canine cases. Socio-environmental analysis revealed that the large amount of animals, organic material from trees and deficiencies in environmental sanitation are possibly contributing to the continuation of the transmission cycle of Leishmania infantum in Araçuaí. These results can contribute to the planning by competent agencies to reduce the incidence of infection in the city.

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The thermopreference of resting P. megistus (Burmeister, 1834) adults was studied in a temperature gradient. We also determined the thermopreference for oviposition and ecdysis. Thermopreference of resting individuals depended on the feeding state of the insects. Results demonstrated an initial resting preference of approximately 290 degrees C, which gradually changed to 26-27 degrees C with increasing starvation. A daily variation in thermopreference was also observed with this species. The insects showed a daily maximum preference at the beginning of the dark phase, and a minimum preference during the first half of the light phase. Ecdysis took place all along the gradient, but exhibited a maximum frequency at 30 degrees C. Most eggs were found between 25 and 29 degrees C. Results are discussed in relation to the ecology of P. megistus as compared with other related species, and the existence of mechanisms of behavioral thermoregulation in the group.

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Triatoma sordida Stal, 1859 is a predominantly peridomiciliary species that is now the most common triatomine in Brazil (L Diotaiuti et al. 1995 Bol Of Sanit Panam 118: 211-219). Its original habitat was probably the Brazilian "cerrado" (OP Forattini 1980 Rev Saúde Públ 14: 265-99) where it occurs mainly under dead or dry bark of trees (MP Barretto 1979, Epidemiologia, p. 425-449. In Z Brener & Z Andrade, Trypanosoma cruzi e Doença de Chagas, Guanabara Koogan, Rio de Janeiro, L Diotaiuti et al. 1993 Rev Inst Med Trop São Paulo 35: 237-245). Due to growing the destruction of its original habitat in the last years, as a consequence of new colonization projects and expansion of cultivated areas, resulting in uncontrolled environment interventions, the population densities of this species have risen considerably in environments modified by human activity (OP Forattini et al. 1974 Rev Saúde Públ 8: 265-282), including peridomiciliary ecotopes (Diotaiuti et al. 1995 loc. cit.). Knowledge of the ecology of T. sordida in the peridomicile is an important prerequisite for its control. In order to determine the factors involved in peridomiciliary infestation by this species, a survey of triatomine following spraying with deltamethrin was carried out at domiciliary units (DUs) of Agrovila 12 farm in Serra do Ramalho county, Bahia, Brazil, according to methods already described (L Diotaiuti et al. 1998 Rev Panam Salud Púb 3: 21-25). This area had not been treated with insecticides for four years prior to the study. From the 378 DUs studied, 196 were positive (51.9%), with intradomiciliary infestation corresponding to 6% and the peridomiciliary to 99%. A total of 1,937 insects were captured and the infestation index was reevaluated at 4, 8 and 12 months after spraying (Figure). During the pre-intervention survey 48.3% of the peridomiciliary ecotopes studied were found to be infested, particularly those with wood as the main construction material (constituting 92.1% of the ecotopes in the survey), where 95.2% of the insects were captured, followed by those using adobe (6.2%), where 3.8% of the insects were captured and finally those composed of several building materials (1.8%), where 1.1% of the insects were captured. These ecotopes comprised chicken houses (46.7%), pigsties (9.3%), fences (33.9%), bathrooms (0.9%) and miscellaneous others (9.3%); the proportions of insects collected in each ecotope was 69.3, 5.4, 19.4, 0.7 and 5.2% respectively (Table I). A total of 2,934 domestic animals were present in the peridomicile at the time of the survey, of which 78.7% were chickens, 12.5% pigs, 5.2% dogs, 3.1% cats and 0.5% ungulates (goats or oxen). These animals were present in 82.4, 46.6, 51.5, 28.9 and 1.5% respectively of the DUs studied. The blood-meal sources identified by the precipitin test were: birds 56.4%, horses 7.2%, rodents 6.7%, human 2.2%, dogs 1.7%, opossum 0.9%, cats 0.1% and ungulates (goats or oxen) 0.1%. It was not possible to identify the source of 29.2% of insect blood-meals due to insufficient quant...