Screening for Leishmania infection in dogs remains a major constraint in the control of dog-associated visceral leishmaniasis. This study evaluated the performance of four diagnostic assays—rK39, multi-antigen rapid diagnostic test strip (MRD), indirect fluorescent antibody test (IFAT), and quantitative polymerase chain reaction (qPCR)—using peripheral blood samples from asymptomatic dogs in endemic areas, with the aim of informing context-specific screening strategies. A total of 175 dogs were tested. Agreement between assays was assessed using Cohen’s and Fleiss’ kappa statistics, and paired differences were evaluated using McNemar’s test. Relative performance was further estimated using two-by-two tables and latent class analysis. The highest proportion of positives was detected by qPCR (30.9%), followed by IFAT (16.0%), MRD (8.6%), and rK39 (6.9%). Agreement was moderate between rK39 and MRD (κ = 0.559) but remained low between the serological assays and qPCR (κ < 0.20). Significant discordance was observed between qPCR and each serological method (P < 0.05). Latent class analysis indicated the highest class-conditional positivity among infected dogs for qPCR (0.99), whereas IFAT showed a higher probability of false-positive results among uninfected dogs (0.12). In the absence of a universally accepted reference standard, these findings supported a tiered screening approach, in which qPCR improved case detection in endemic settings, while initial screening with rK39 or MRD followed by qPCR confirmation provided a practical balance between feasibility and diagnostic accuracy.
Wu et al. (Tue,) studied this question.