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Risk factors for seroconversion by Leishmania infantum in a cohort of dogs from an endemic area of Brazil.

Coura-Vital W, Reis AB, Fausto MA, Leal GG, Marques MJ, Veloso VM, Carneiro M - PLoS ONE (2013)

Bottom Line: A molecular diagnostic method (PCR-restriction fragment length polymorphism) and a structured questionnaire were also used.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.

View Article: PubMed Central - PubMed

Affiliation: Pós-Graduação em Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil ; Núcleo de Pesquisas em Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil ; Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.

ABSTRACT
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.

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Related in: MedlinePlus

Baseline survey; evaluations I, II, and III; and losses to follow-up, Belo Horizonte, Minas Gerais.
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pone-0071833-g001: Baseline survey; evaluations I, II, and III; and losses to follow-up, Belo Horizonte, Minas Gerais.

Mentions: The first follow-up study was initiated 10 months after the baseline survey (April 2009, designated evaluation I) during the VLCSP canine survey census, and a total of 455 dogs were enrolled. Households with seronegative/PCR– dogs were selected by proximity to households with seronegative/PCR+ dogs. The canines were selected from 333 owners, who were interviewed with a precoded questionnaire to identify risk factors related to seroconversion. All dogs were clinically examined, and blood was collected by venipuncture. Evaluation II was conducted 16 months after the baseline survey (October 2009), and 369 dogs were included. Evaluation III was carried out 26 months after the baseline survey (August 2010), and 280 dogs were tested (Figure 1). All the dogs included in evaluations II and III were subjected to the same procedures used for evaluation I.


Risk factors for seroconversion by Leishmania infantum in a cohort of dogs from an endemic area of Brazil.

Coura-Vital W, Reis AB, Fausto MA, Leal GG, Marques MJ, Veloso VM, Carneiro M - PLoS ONE (2013)

Baseline survey; evaluations I, II, and III; and losses to follow-up, Belo Horizonte, Minas Gerais.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3750039&req=5

pone-0071833-g001: Baseline survey; evaluations I, II, and III; and losses to follow-up, Belo Horizonte, Minas Gerais.
Mentions: The first follow-up study was initiated 10 months after the baseline survey (April 2009, designated evaluation I) during the VLCSP canine survey census, and a total of 455 dogs were enrolled. Households with seronegative/PCR– dogs were selected by proximity to households with seronegative/PCR+ dogs. The canines were selected from 333 owners, who were interviewed with a precoded questionnaire to identify risk factors related to seroconversion. All dogs were clinically examined, and blood was collected by venipuncture. Evaluation II was conducted 16 months after the baseline survey (October 2009), and 369 dogs were included. Evaluation III was carried out 26 months after the baseline survey (August 2010), and 280 dogs were tested (Figure 1). All the dogs included in evaluations II and III were subjected to the same procedures used for evaluation I.

Bottom Line: A molecular diagnostic method (PCR-restriction fragment length polymorphism) and a structured questionnaire were also used.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.

View Article: PubMed Central - PubMed

Affiliation: Pós-Graduação em Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil ; Núcleo de Pesquisas em Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil ; Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus