Evaluation of parasitological examination, kDNA polymerase chain reaction and rK39-based immunochromatography for the diagnosis of visceral leishmaniasis in seropositive dogs from the screening-culling program in Brazil

Abstract

Introduction: Dogs play a primary role in the zoonotic cycle of visceral leishmaniasis (VL). Therefore, the accurate diagnosis of infected dogs, primarily asymptomatic dogs, is crucial to the effi ciency of VL control programs. Methods: We investigated the agreement of four diagnostic tests for canine visceral leishmaniasis (CVL): parasite detection, either after myeloculture or by direct microscopic examination of tissue imprints; kinetoplast-deoxyribonucleic acid-polymerase chain reaction (kDNA-PCR); and an immunochromatographic test (ICT). An enzyme-linked immunosorbent assay (ELISA) and an indirect immunofl uorescence test (IFAT), both of which were adopted as part of the screening-culling program in Brazil, were used as reference tests. Our sample set consisted of 44 seropositive dogs, 25 of which were clinically asymptomatic and 19 were symptomatic for CVL according to ELISA-IFAT. Results: The highest and lowest test co-positivities were observed for ICT (77.3%) and myeloculture (58.1%), respectively. When analyzed together, the overall percentage of co-positive tests was signifi cantly higher for the symptomatic group compared to the asymptomatic group. However, only ICT was signifi cantly different based on the results of a separate analysis per test for each group of dogs. The majority (93.8%) of animals exhibited at least one positive test result, with an average of 2.66 positive tests per dog. Half of the symptomatic dogs tested positive for all four tests administered. Conclusions:The variability between test results reinforces the need for more effi cient and reliable methods to accurately diagnose canine VL, particularly in asymptomatic animals.

Epidemiological aspects of vector, parasite, and domestic reservoir in areas of recent transmission and no reported human cases of visceral leishmaniasis in Brazil

“…In a recent comparison of diagnostic tests for VL, by our group, the immunochromatography reached up to 77.3% of co-positivity compared to ELISA-IFA. Although the canine sample was limited to 44 dogs, those data reinforced that more sensitive and specific tests need to be developed before the efficient diagnosis of canine VL can be performed (Regina-Silva et al, 2014).…”

The performance of serological tests for Leishmania infantum infection screening in dogs depends on the prevalence of the disease

“…Despite their lower sensitivity, laboratory methods considered gold standards for VL confirmation are parasitological approaches 17 . Detection of parasites in tissues, organs or cultures establishes the conclusive diagnosis of L. infantum infection in dogs 12 .…”

Epitope mapping of recombinant Leishmania donovani virulence factor A2 (recLdVFA2) and canine leishmaniasis diagnosis using a derived synthetic bi-epitope

“…In humans, infection with Leishmania can cause a broad spectrum of symptoms ranging from a clinically silent infection to a fatal visceral disease [ 2 ]. In an urban environment, dogs are the main reservoir of the disease, but many stay asymptomatic, showing no clinical signs [ 3 , 4 , 5 ].…”