Validation of the Dual-path Platform chromatographic immunoassay (DPP® CVL rapid test) for the serodiagnosis of canine visceral leishmaniasis

Abstract

BACKGROUND Visceral leishmaniasis is a major public health challenge in South America, and dogs are its main urban reservoir. OBJECTIVE Validation of the canine Dual-path Platform immunoassay for canine visceral leishmaniasis (DPP ® CVL) for a sample set composed of 1446 dogs from different Brazilian endemic areas. METHODS A well-defined reference standard by means of parasitological culture, immunohistochemistry, and histopathology was used. Animals were classified as asymptomatic, oligosymptomatic, or symptomatic. Sensitivity and specificity were assessed as a single set and in clinical groups. A reproducibility assessment of the tests was conducted using the Kappa (κ) index at three different laboratories (A, B, and C). FINDINGS Overall, 89% sensitivity and 70% specificity were obtained for the entire sample set. Analysis of the clinical groups showed a gradual decrease in the sensitivity and an increase in the specificity with the reduction of clinical signs in the dogs that were assessed, reaching a sensitivity of 75% (42.8-94.5%) among asymptomatic dogs and lower specificity of 56% (46.2-66.3%) among symptomatic dogs. Inter-laboratory agreement was substantial (κ AB = 0.778; κ AC = 0.645; κ CB = 0.711). MAIN CONCLUSIONS The test performance is somewhat dependent on canine symptomatology, but such influence was less evident than in previous studies. Favourable results for sensitivity and specificity can be obtained even in asymptomatic animals; however, caution is needed in these evaluations, and the results suggest that the immunochromatographic test may be further improved for better investigation in asymptomatic dogs. The results obtained confirm the usefulness of DPP ® CVL for application in serological surveys.

Improving the reference standard for the diagnosis of canine visceral leishmaniasis: a challenge for current and future tests

“… 4 A larger study, using the same reference standard, made subgroup analysis based on the presence of symptoms revealing that TR-DPP for asymptomatic dogs had a sensitivity of 75% (CI95% 42.8 to 94.5) and specificity of 72.9% (CI95% 68.5 to 77.1) compared to sensitivity of 93.8% (CI95% 82.8 to 98.7) and specificity of 56.4% (CI95% 46.2% to 66.3%) in symptomatic dogs. 8 Finally, DAT- Canis showed a sensitivity of 97% in symptomatic dogs, 21 and its performance had not been previously assessed in diagnosing asymptomatic dogs.…”

“…33 Studies conducted later have evaluated the sensitivity and specificity of these tests. 4 , 5 , 8 , 34 , 35 , 36 , 37 However, the lack of a homogenous reference standard has caused the results of these studies to diverge, as each one has used a different criterion for defining infected cases.…”

“…Molecular diagnostic tests are not routinely used in public health programs because of the relative difficulties regarding the need for complex laboratorial infrastructure, the elevated costs, and the lack of commercially available assays, as well as other limitations. 7 , 8 , 9 , 10 …”

eNose analysis of volatile chemicals from dogs naturally infected with Leishmania infantum in Brazil

“…The DPP CVL test has also been assessed several times since it was introduced and most recently it has been shown that overall it has 86% sensitivity and 94% specificity[14] or 89% sensitivity and 70% specificity[15].…”

Volatile organic chemical analyser (eNose) diagnosis of dogs naturally infected with visceral leishmaniasis in Brazil

“…The DPP CVL test has been assessed several times since it was introduced. The most recent assessment showed that it has 75% sensitivity and 73% specificity for asymptomatic dogs and 94% sensitivity and 56% specificity for symptomatic dogs (Figueiredo et al, 2018) suggesting that the DPP test is better for confirming than identifying cases (Grimaldi et al, 2012).…”