A systematic review and meta-analysis of the factors associated with Leishmania infantum infection in dogs in Brazil.

The risk factors associated with canine visceral leishmaniosis (CVL) in Brazil are unclear and controversial. The objectives of this systematic review and meta-analysis were to identify the best evidence available in this field and to determine the gaps in existing knowledge. Literature searches were carried out using four databases, the reference lists within articles, and references provided by experts in the field. Theoretical discussions or separate and independent meta-analyses of p-values or of effect sizes were used to pool information about each variable. Thirty-six articles were selected for detailed review, including 31 cross-sectional, two ecological and three cohort studies. The variables showing significant association with CVL were short hair, purebred, peri-domestic restricted (as compared with domestic-restricted dogs), and presence of green areas adjacent to home. The occurrence of CVL was also associated with the presence of domestic fowl in the home environment, with free dogs (as compared with restrained dogs), with male gender and with dogs >1 or 2 years of age, although these associations were not statistically significant. Due to the small number of publications, consistent results could not be obtained concerning the role of other factors. Most studies did not describe the criteria of eligibility and the process of selection of participants in sufficient detail and employed only one diagnostic test as proof of infection. Few studies controlled for confounding variables. No statistical evidence of publication bias was detected, but a great deal of information contained in the primary articles was lost because the results were not adequately described. The results of this review contribute to a better understanding of CVL and should assist in optimizing the development and implementation of control policies. Continuous actions, prioritizing dogs at higher risk and areas with higher abundance of green vegetation, together with policies to promote responsible dog ownership are mandatory. Problems concerning study design and data analysis described in the present study need to be taken into consideration in future studies. These must follow clear procedures to select participants and utilize standardized, valid and reliable diagnostic methods. The development of multivariate models and the use of the STROBE statement for description of the results should also be encouraged. Further research should investigate the patterns identified and prioritize CVL-related factors that have not been fully recognized or elucidated. Finally, ecological and cohort studies of CVL and investigations in other countries of Latin America are urgently required.

Study of sand flies (Diptera: Psychodidae) in visceral and cutaneous leishmaniasis areas in the central-western state of Minas Gerais, Brazil.

The transmission of Leishmania involves several species of sand flies that are closely associated with various parasites and reservoirs, with differing transmission cycles in Brazil. A study on the phlebotomine species composition has been conducted in the municipality of Divinópolis, Minas Gerais, Brazil, an endemic area for cutaneous leishmaniasis (CL), which has intense occurrence of visceral leishmaniasis (VL) cases. In order to study the sand flies populations and their seasonality, CDC light traps (HP model) were distributed in 15 houses which presented at least one case of CL or VL and in five urban parks (green areas). Collections were carried out three nights monthly from September 2010 to August 2011. A total of 1064 phlebotomine specimens were collected belonging to two genera and seventeen species: Brumptomyia brumpti, Lutzomyia bacula, Lutzomyia cortelezzii, Lutzomyia lenti, Lutzomyia sallesi, Lutzomyia longipalpis, Lutzomyia migonei, Lutzomyia intermedia, Lutzomyia neivai, Lutzomyia whitmani, Lutzomyia christenseni, Lutzomyia monticola, Lutzomyia pessoai, Lutzomyia aragaoi, Lutzomyia brasiliensis, Lutzomyia lutziana, and Lutzomyia sordellii. L. longipalpis, the main vector of Leishmania infantum in Brazil, was the most frequent species, accounting for 76.9% of the total, followed by L. lenti with 8.3%, this species is not a proven vector. Green and urban areas had different sand flies species composition, whereas the high abundance of L. longipalpis in urban areas and the presence of various vector species in both green and urban areas were also observed. Our data point out to the requirement of control measures against phlebotomine sand flies in the municipality of Divinópolis and adoption of strategies aiming entomological surveillance.