Validity and Reliability of Enzyme Immunoassays Using Leishmania major or L. infantum Antigens for the Diagnosis of Canine Visceral Leishmaniasis in Brazil

Abstract

BackgroundAmerican visceral leishmaniasis is caused by the protozoan Leishmania infantum. Dogs are the main reservoirs in the domestic transmission cycle. The limited accuracy of diagnostic tests for canine leishmaniasis may contribute to the lack of impact of control measures recommended by the Brazilian Ministry of Health. The objective of this study was to estimate the accuracy of two enzyme-linked immunosorbent assays employing L. major or L. infantum antigens and their reliability between three laboratories of different levels of complexity.MethodsA validation study of ELISA techniques using L. major or L. infantum antigens was conducted. Direct visualization of the parasite in hematoxylin/eosin-stained histopathological sections, immunohistochemistry, and isolation of the parasite in culture.were used as gold standard. An animal that was positive in at least one of the tests was defined as infected with L. infantum. Serum samples collected from 1,425 dogs were analyzed. Samples were separated in three aliquots and tested in three different laboratories. Sensitivity, specificity and the area under de ROC curve were calculated and the reliability was evaluated between the participant laboratories.ResultsThe sensitivity was 91.8% and 89.8% for the L. major and L. infantum assays, respectively. The specificity was 83.75% and 82.7% for the L. major and L. infantum assays, respectively. The area under de ROC curve was 0.920 and 0.898 for L. major and L. infantum, respectively. The mean intraclass correlation coefficients between laboratories ranged from 0.890 to 0.948 when L. major was used as antigen, and from 0.818 to 0.879 when L. infantum was used.InterpretationELISA tests using L. major or L. infantum antigens have similar accuracy and reliability. Our results do not support the substitution of the L. major antigen of the ELISA test currently used for the diagnosis of canine visceral leishmaniasis in Brazil.

Serological diagnosis of canine visceral leishmaniasis in Brazil: systematic review and meta‐analysis

“…Of 25 studies evaluated, only two (MS ; de Arruda et al . ) presented simultaneously a low risk of bias, a low risk for applicability and good performance in the questions proposed by STARD, indicating that the results identified by these studies constitute strong evidence. However the low risk of bias related to the reference standard should be taken with precaution because of the limitations of the compound parasitological test.…”

“…As shown in Table , only two studies (MS ; de Arruda et al . ) did not present any risk of bias in any of the evaluated domains. Of the 25 articles evaluated, three did not present risks of bias regarding selection of individuals, eight with regard to the test being evaluated, four with regard to the reference standard and 12 regarding flow.…”

Thick Smear is a Good Substitute for the Thin Smear in Parasitological Confirmation of Canine Visceral Leishmaniasis

“…1 In Brazil, visceral leishmaniasis (VL) is spreading; therefore, efforts have been made to improve the diagnostic accuracy in dogs. 2,3 Currently, the dual path platform (DPP) rapid immunochromatographic assay and enzyme-linked immunosorbent assay (ELISA; Canine VL [CVL]) are used for diagnostic screening and confirmation respectively in these animals; positive animals are then euthanized in an attempt to stop the transmission cycle. 1,4 This strategy is applied in areas with confirmed cases of human or CVL where parasitological examinations are not conducted because of the extensive amount of work that is required.…”

Serological, parasitological and molecular tests for canine visceral leishmaniosis diagnosis in a longitudinal study

“…However, the Brazilian Ministry of Health currently recommends its use with serum samples. Thus, DPP is performed in a laboratory and positivity is confirmed by means of an ELISA test (EIE-Bio-Manguinhos®) in order to ensure greater sensitivity and specificity (ARRUDA et al, 2013). Silva et al (2013) observed greater sensitivity for DPP (93%) than was seen from the data presented herein.…”