Comparative evaluation of several methods for Canine Visceral Leishmaniasis diagnosis

Abstract

The aim of the present study was to evaluate the serological methods using ELISA with recombinant-rK39 (ELISA-rK-39) and soluble extract-SE (ELISA-SE) antigens, the indirect fluorescence antibody test (IFAT) in comparison to an immunochromatography rapid diagnostic test (RDT-rK39) and with a direct parasitological exam (PA) for Canine Visceral Leishmaniasis (CVL) diagnosis. The results showed that 89% (60/67) of the dogs were positive for at least one serological diagnostic test. ELISA-SE was the test that detected anti-Leishmania antibodies in the serum of the highest number of dogs (71.6%) followed by ELISA-rK39 (65.7%), IFAT (65.7%) and RDT-rK39 (55.2%). PA detected the lowest numbers (40.3%) of positive dogs. In relation to the total of examined dogs, the Kappa indexes (p ≤ 0.05) showed a good agreement between ELISA-SE and IFAT (88.1%; k = 0.7237), and it was also observed in the comparison of RDT-rK39 with ELISA-SE (83.6%, k= 0.6561), IFAT (83.5%, k= 0.6605) and PA (85.0%, k= 0.7074). A bad agreement was detected in any association of ELISA-rk39 with the other tests in either symptomatic or asymptomatic animals. ELISA as well as RDT using recombinant antigenic protein (rK39) were the methods that detected the lowest prevalence rates (33.3%) of CVL in asymptomatic dogs. In conclusion, only one test does not adequately identify dogs with CVL and it is necessary the association of two or more diagnostic tests. Because of the good agreement indexes of RDT-rK39 when evaluated with ELISA-SE, IFAT and PA it was suggested as a complementary method to be used in association with either ELISA-SE or IFAT, particularly in the symptomatic dogs. Furthermore, new studies are recommended in order to improve the sensitivity of tests mainly for asymptomatic dogs.Keywords: CVL, diagnosis, dogs, Leishmania infantum, rK39, RDT. ResumoO objetivo do presente estudo foi avaliar os métodos sorológicos usando ELISA (Ensaio Imunoenzimático Indireto) com o antígeno recombinante rK39 (ELISA-rK39) e o antígeno extrato solúvel bruto (ELISA-ES) e a RIFI (Reação de Imunofluorescência Indireta) em comparação com o método imunocromatográfico rápido (RDT-rK39) e o parasitológico direto (PA), para o diagnóstico da Leishmaniose Visceral Canina (LVC) em cães de Ilha Solteira, São Paulo, Brasil. Os resultados mostraram que 89% (60/67) dos cães foram positivos por pelo menos um teste diagnóstico sorológico (RIFI, ELISA-ES, ELISA-rk39 ou RDT-rK39) e somente 40,3% (27/67) foram positivos pelo PA. O ELISA-ES foi o teste que detectou anticorpos anti-Leishmania em maior número de cães (71,6%) seguido por ELISArK39, RIFI (65,7%) e por 2%). No total de cães analisados (assintomáticos e sintomáticos), o índice Kappa de concordância (p ≤ 0,05) foi considerado de boa concordância entre ELISA-ES e IFAT (88,1%; k= 0,7237) e entre RDT-rK39 com ELISA-ES (83,6%, k= 0,6561), RIFI (83,5%, k= 0,6605) e PA (85,0%, k= 0,7074). O índice de concordância ruim foi observado em qualquer associação de ELISA-rk39 com todos os outros testes nos animais sintomáticos ...

Detection of Leishmania spp. using parasitological, serological and molecular assays in asymptomatic and sick cats from an endemic area of visceral leishmaniosis in Brazil

“…However, we observed that ELISA-rK39 was more effective in the detection of clinically normal cats, which contrasts in studies performed in dogs. Despite of the effectiveness in the detection of infection in dogs with clinical signs, there was poor efficacy in the use of recombinant protein in asymptomatic animals [38,46]. Thus, we observed the effectiveness of the use of recombinant proteins for the early diagnosis of infection in cats, as the clinical status of these animals is poorly known regarding Leishmania infection.…”

“…The present study was the first report of Leishmania infection in domestic cats from an area that is considered endemic for VL, with several reported cases of the disease in dogs and wild animals [37,38]. The animals of this study were from an animal rights association that shelters abandoned dogs and cats.…”

Molecular detection of Leishmania infantum DNA according to clinical stages of leishmaniasis in dog

“…infection in dogs at several clinical stages and our results showed variation in sensitivity between the primer sets used. The sensitivity of each technique may vary over the course of evolution of the disease and between individuals; therefore, a combination of serological and molecular tests may be necessary to correct the diagnosis (ASSIS et al, 2010;NUNES et al, 2007;QUEIROZ et al, 2010;SILVA et al, 2014). In addition, it has been recommended that the diagnosis of this disease should be based on clinical signs and on the epidemiological characteristics of the region, which may contribute towards correctly identifying truly positive animals (SILVA et al, 2014).…”

Occurrence of Lutzomyia longipalpis (Phlebotominae) and canine visceral leishmaniasis in a rural area of Ilha Solteira, SP, Brazil

“…In this place, there was a kennel with a great concentration of captured dogs and cats that had been abandoned by their owners. Silva et al (2014) found that 89% of these dogs were infected with CVL, thus showing that this place had a potential risk of maintaining and disseminating the disease.…”