Dataset Information

Risk Profiles for Leishmania infantum Infection in Brazil.

ABSTRACT: The aim of this study was to characterize risk profiles for Leishmania infantum infection in a population living in an area endemic for visceral leishmaniasis. A cohort study was conducted between January 2004 and December 2006 with the participation of 430 individuals living in the city of Teresina, northeast Brazil, who were initially negative for the Montenegro test. Data analysis was performed using the classification and regression tree method. The cumulative incidence (CI) of Montenegro's test conversion was 35% at 18-month follow-up. Eight different risk profiles for L. infantum infection were identified. The profile with the highest risk (CI = 75%) comprised individuals with less than 4 years of education who had never lived outside Teresina. The profile with the lowest risk (CI = 5%) included highly educated subjects who had owned a dog for 5 years or more and lived in areas that received some type of intervention. These results show that there is a high degree of complexity involved in the risk for L. infantum infection and point out the need of developing new studies to perform a comprehensive analysis focused on investigating the interrelation between risk factors rather than their isolated roles on the determination of infection levels in urban areas.

SUBMITTER: Alves EB

PROVIDER: S-EPMC4889744 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Risk Profiles for Leishmania infantum Infection in Brazil.

Alves Erika Barretto EB Costa Carlos Henrique Nery CH de Carvalho Fernando Aécio Amorim FA Pires E Cruz Maria do Socorro Mdo S Werneck Guilherme Loureiro GL

The American journal of tropical medicine and hygiene 20160425 6

The aim of this study was to characterize risk profiles for Leishmania infantum infection in a population living in an area endemic for visceral leishmaniasis. A cohort study was conducted between January 2004 and December 2006 with the participation of 430 individuals living in the city of Teresina, northeast Brazil, who were initially negative for the Montenegro test. Data analysis was performed using the classification and regression tree method. The cumulative incidence (CI) of Montenegro's ...[more]

PMID: 27114290

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Project description:BackgroundThe sand fly Nyssomyia neivai is one of the most abundant species in Southern Brazil. It is frequently found in areas that are foci of visceral leishmaniasis in the state of Santa Catarina, caused by Leishmania infantum. In this region, the main vector of L. infantum, Lutzomyia longipalpis, has not been detected. In the absence of L. longipalpis, this study aimed to identify the sand fly fauna and diagnose any potential Leishmania spp. infection in sand flies and in dogs in a region of Southern Brazil that experienced a recent canine visceral leishmaniasis outbreak.MethodsThis report includes a survey of the sand fly fauna at the Zoonosis Control Center of the Municipality of Tubarão (Santa Catarina, Brazil). Molecular tests were conducted to investigate Leishmania spp. natural infection in sand flies using polymerase chain reaction (PCR). In positive females, in addition to morphological identification, molecular analysis through DNA barcoding was performed to determine the sand fly species. Additionally, the dogs were tested for the presence of Leishmania spp. using a non-invasive technique for the collection of biological material, to be assessed by PCR.ResultsA total of 3419 sand flies, belonging to five genera, were collected. Nyssomyia neivai was the most abundant species (85.8%), followed by Migonemyia migonei (13.3%), Pintomyia fischeri (0.8%), Evandromyia edwardsi (< 0.1%), and species of the genus Brumptomyia. (0.1%). Out of the 509 non-engorged females analyzed by PCR, two (0.4%) carried L. infantum DNA. The naturally infected females were identified as Ny. neivai, in both morphological and molecular analysis. In addition, two out of 47 conjunctival swabs from dogs tested positive for L. infantum, yielding an infection rate of 4.2%.ConclusionsThese results confirm the presence of Ny. neivai naturally infected with L. infantum in an area where dogs were also infected by the parasite, suggesting its potential role as a vector in Southern Brazil.

Project description:Visceral leishmaniasis (VL) has recently emerged in various urban and peri-urban areas of Brazil and other countries. Understanding the urbanization of VL requires identification of risk factors associated with human and canine infection. To determine the predictors of risk for canine VL, a survey was conducted of 1,443 dogs, from which a cohort was selected (n = 455) and evaluated for approximately 26 months. Serology was conducted with two enzyme-linked immunosorbent assays (ELISA): one conducted in the Laboratory of Zoonosis of the Belo Horizonte Health Department (LZOON) and the other in the Laboratory of Immunopathology of the Federal University of Ouro Preto (LIMP). A molecular diagnostic method (PCR-restriction fragment length polymorphism) and a structured questionnaire were also used. To identify the factors associated with seroconversion, two time-dependent Cox regression models were performed with different sensitivities (model 1, seroconversion by ELISA/LZOON; model 2, seroconversion by ELISA/LIMP). The overall incidences of seroconversion were 6.5/1000 dogs-months and 11.2/1000 dogs-months for ELISA/LZOON and ELISA/LIMP, respectively. Increased risk of seroconversion was associated with short fur (model 1: hazard ratio [HR] 1.9), the presence of dry leaves (model 1: HR 2.8) or manure (model 1: HR 3.5) in the backyard, dogs sleeping predominantly in the backyard (model 2: HR 2.1), the presence of symptoms (model 2: HR 2.0), and positive molecular results during follow-up (model 2: HR 1.5). Decreased risk was associated with insecticide spraying in the house (model 2: HR 0.5). These results indicate that more-vulnerable domiciles, certain dog behaviors, lack of vector control measures, and positive molecular results were associated with the occurrence of canine VL. Furthermore, it is important to emphasize that PCR-positive dogs should be monitored, owing to the possibility of seroconversion. Identifying risk factors for seroconversion in dogs is crucial for developing adequate strategies for VL prevention and control.

Dataset Information

Risk Profiles for Leishmania infantum Infection in Brazil.

Publications

Risk Profiles for Leishmania infantum Infection in Brazil.

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