title: Risk factors for seroconversion by Leishmania infantum in a cohort of dogs from an endemic area of 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.
authors.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.
authors.forename: Wendel
authors.initials: W
authors.lastname: Coura-Vital
authors.forename: Alexandre Barbosa
authors.initials: AB
authors.lastname: Reis
authors.forename: Maria Arlene
authors.initials: MA
authors.lastname: Fausto
authors.forename: Gleisiane Gomes de Almeida
authors.initials: GG
authors.lastname: Leal
authors.forename: Marcos José
authors.initials: MJ
authors.lastname: Marques
authors.forename: Vanja Maria
authors.initials: VM
authors.lastname: Veloso
authors.forename: Mariângela
authors.initials: M
authors.lastname: Carneiro
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D001938:Brazil / Q000453:epidemiology; D016054:DNA, Protozoan / Q000235:genetics; D004283:Dog Diseases / Q000097:blood / Q000453:epidemiology* / Q000469:parasitology; D004285:Dogs; D019353:Endemic Diseases / Q000706:statistics & numerical data / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015994:Incidence; D018314:Leishmania infantum / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D007898:Leishmaniasis, Visceral / Q000097:blood / Q000469:parasitology / Q000662:veterinary*; D008297:Male; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015995:Prevalence; D016016:Proportional Hazards Models; D012307:Risk Factors; D015047:Zoonoses / Q000453:epidemiology / Q000469:parasitology
chemical_list: D000913:Antibodies, Protozoan; D016054:DNA, Protozoan