ABSTRACT
BACKGROUND Dogs are the main peridomiciliary reservoir of Leishmania infantum thus the correct diagnosis of infection is essential for the control of the transmission and treatment as well. However, the diagnosis is based on serological assays that are not fully effective. OBJECTIVE We aimed to establish an effective serological assay for the diagnosis of L. infantum infected dogs using Leishmania-derived recombinant antigens. METHODS Leishmania derived rK39-, rK28-, rKR95-based enzyme-linked immunosorbent assay (ELISA) was standardized using symptomatic and asymptomatic L. infantum-infected dogs. Then 2,530 samples from inquiry in endemic areas for VL were evaluated and the results compared with recommended assays by the Brazilian Ministry of Health (MH algorithm). Further samples from a cohort of 30 dogs were searched. FINDINGS For rK39-, rK28- and rKR95-ELISA the sensitivity was around 97% and specificity 100%. The positivity of these three ELISA in the inquiry samples was 27-28%, around 10% higher than the assays currently in use. When cohort samples were searched, we observed likely false-negative results (> 65%) with supposedly negative samples that turned positive six months later with the assays in use (MH algorithm). MAIN CONCLUSIONS For the diagnosis of L. infantum-infected dogs, rK39-based ELISA showed better diagnostic performance than other assays in use in Brazil and worldwide.
Subject(s)
Animals , Dogs , Enzyme-Linked Immunosorbent Assay/standards , Enzyme-Linked Immunosorbent Assay/veterinary , Antibodies, Protozoan/blood , Leishmania infantum/immunology , Dog Diseases/diagnosis , Leishmaniasis, Visceral/diagnosis , Recombinant Proteins/immunology , Brazil , Enzyme-Linked Immunosorbent Assay/methods , Serologic Tests , Sensitivity and Specificity , Leishmania infantum/isolation & purification , Leishmaniasis, Visceral/blood , Leishmaniasis, Visceral/veterinary , Antigens, Protozoan/biosynthesisABSTRACT
Abstract Efforts to control a zoonotic disease such as visceral leishmaniasis (VL) caused by Leishmania infantum can be successful if they rely on comprehensive data on animal infection. In Bahia state, Brazil, human VL is endemic, yet some areas have no epidemiological data on canine L. infantum infection and canine leishmaniasis (CanL) to date. We aimed to perform an epidemiological study describing the spatial distribution and characterizing canine L. infantum infection in two districts of the municipality of Muritiba, where human cases have occurred. Brazilian official serodiagnostic protocol (ELISA and immunochromatographic tests), PCR and clinical examination were performed in 351 owned dogs. A seroprevalence of 15.7% (55/351) was found, and L. infantum identified in 88.8% (32/36) of PCR tested samples. Spatial distribution of positive dogs indicated infection in both urban and rural districts. There was no association between seropositivity and sex or breed, but dogs older than 2 years were 3.8 times more likely to be seropositive (95% CI 1.57 - 9.18) than younger dogs. Among seropositive dogs, 80% (44/55) had clinical manifestations of CanL: 75% (33/44) presented dermatopathy, 50% (22/44) emaciation, and 29.5% (13/44) ophthalmopathy. This is the first report on canine seroprevalence and natural L. infantum infection in Muritiba, Bahia.
Resumo O sucesso dos esforços para controlar uma doença zoonótica como a leishmaniose visceral (LV), causada por Leishmania infantum, depende de dados abrangentes sobre a infecção animal. Na Bahia, Brasil, embora a LV humana seja endêmica, diversos municípios, como Muritiba, ainda não dispõem de dados epidemiológicos sobre infecção por L. infantum e leishmaniose canina (LCan). Objetivou-se realizar um estudo epidemiológico para descrever a distribuição espacial e caracterizar a infecção canina por L. infantum em dois distritos de Muritiba, onde notificam-se casos humanos. Foi aplicado o protocolo sorodiagnóstico oficial brasileiro (ELISA e imunocromatografia), PCR e exame clínico em 351 cães domiciliados. Encontrou-se uma soroprevalência de 15,7% (55/351) e positividade de 88,8% (32/36) na PCR para L. infantum. A distribuição espacial dos cães positivos indicou infecção em ambos os distritos, urbano e rural. Não houve associação entre soropositividade e sexo ou raça, mas cães com idade acima de 2 anos foram 3,8 vezes mais soropositivos (IC 95% 1,57 - 9,18). Dentre os cães soropositivos, 80% (44/55) apresentavam manifestações clínicas de LCan: 75% (33/44) apresentavam dermatopatia; 50% (22/44) emagrecimento e 29,5% (13/44) oftalmopatia. Este é o primeiro estudo a determinar a soroprevalência e confirmar a circulação natural de L. infantum e LCan em cães de Muritiba.