Canine visceral leishmaniasis in an urban setting of Southeastern Brazil: an ecological study involving spatial analysis

Abstract

Background: The physical characteristics of the environment influence the composition, distribution and behavior of the vectors and mammalian hosts involved in the transmission of visceral leishmaniasis (VL), thereby affecting the epidemiology of the disease. In Brazil, urbanization of human VL is a recent phenomenon and represents an issue of particular concern to local health authorities. The present study aimed to establish the degree of spatial dependency between canine and human VL in the municipality of Divinópolis, Minas Gerais, Brazil, and to identify priority risk areas in which stricter control measures should be implemented. Methods: The selected canine population comprised 3,652 dogs distributed within 11 strata and 1,247 urban blocks. Serum samples were collected between March 2013 and February 2014. Serodiagnosis of dogs was performed using the enzyme-linked immunosorbent assay and the indirect fluorescent-antibody test. The blocks sampled for canine VL and the addresses of the 16 confirmed cases of human VL notified in Divinópolis during the period 2007-2013 were georeferenced. Spatial analysis of the data was performed using Kernel density estimation, Ripley's bivariate K-function and directional distribution methods. Results: The overall prevalence of seropositive animals was 4.63% (range 3.95 -5.31) (n =169) and varied in different strata between 0.9 (range 0.0 -1.91) and 8.73% (range 5.65 -11.81). A positive spatial dependency was detected between human and canine VL in which the occurrence of human cases of the disease tended to concentrate in locations that were close to areas with a higher incidence of canine VL. The priority risk area could be clearly distinguished from Kernel density estimation and standard deviational ellipse plots in which the human VL ellipse was totally enclosed within the canine VL ellipse. Conclusions: The results presented herein will enable the Municipal Health Office of Divinópolis to devise a more effective management plan for human VL in which specific strategies would be applied to areas presenting different levels of risk. This spatial evaluation of leishmaniasis model could be applied in other urban areas of Brazil.

Transcriptomic responses of Biomphalaria pfeifferi to Schistosoma mansoni: Investigation of a neglected African snail that supports more S. mansoni transmission than any other snail species

“…pfeifferi-S . mansoni system studied here is noteworthy for the high degree of susceptibility shown by the snail to infection [ 15 , 16 ]. Compatibility with S .…”

“…Details of recruitment and participation of human subjects for fecal collection are described in Mutuku et al . [ 15 ]. This project was undertaken with approval of Kenya’s National Commission for Science, Technology, and Innovation (permit number NACOSTI/P/15/9609/4270), National Environment Management Authority (NEMA/AGR/46/2014) and an export permit has been granted by the Kenya Wildlife Service (0004754).…”

“…Snails sized 6-9mm in shell diameter were placed into 24-well culture plates and exposed to natural light to check for the shedding of digenetic trematode cercariae, including cercariae of S . mansoni [ 15 ]. Snails found to be shedding cercariae of other digenetic trematode species were excluded from this study.…”

“…Biomphalaria pfeifferi confirmed to be uninfected were exposed to S . mansoni using standard methods to hatch the parasite eggs [ 15 ]. Snails were individually exposed to 20 miracidia for 6 hours in 24-well culture plates and then returned to aquaria.…”

Leishmania infantum INFECTION IN DOGS FROM THE SOUTHERN REGION OF MINAS GERAIS STATE, BRAZIL

“…In 1989, the death of a two-year-old child from VL was reported in Belo Horizonte , the capital of the state 15 , and in the same study, the presence of infected dogs and of the vector L. longipalpis was verified in various districts of the city. Other cases were described in Governador Valadares 16 , Montes Claros 17 and Divinópolis 18 , municipalities in the northern region of the state, and in Juiz de Fora 19 and Lavras 20 , located in the southern region of the state. Currently, the region of Belo Horizonte , the state capital, has the highest incidence of VL and the higher risk of disease transmission 21 , 22 .…”