Comparative performance of the novel, point-of-care Pluslife Mini Dock Dirofilaria immitis/Dirofilaria repens detection test with the modified Knott’s test in dogs

BACKGROUND: The current American Heartworm Society guidelines recommend the concomitant use of an antigen detection test and a microfilariae detection test (MFDT) for diagnosing heartworm infection in dogs. The modified Knott's (MK) test is the preferred MFDT for determining the morphological characteristics of Dirofilaria immitis microfilariae, but it requires extensive microscopy training and can be time-consuming in a clinical setting. The Pluslife Mini Dock is a point-of-care diagnostic platform that uses RNase HII-assisted amplification (RHAM) to eliminate the need for DNA extraction, with results available within 30 min. This study aimed to assess the performance of the Pluslife Mini Dock duplex Dirofilaria immitis/Dirofilaria repens assay in dog blood compared with the MK. METHODS: Archival, frozen whole-blood samples collected from 250 dogs at shelters in central Texas, USA, were used. Samples were subjected to the MK on the day of collection and stored at 2°C until further processing. The samples were then thawed and subjected to the Pluslife Mini Dock D. immitis/D. repens duplex assay. The results were analyzed using Cohen's kappa coefficient and McNemar's Chi-squared test. RESULTS: Overall, 93.6% of results matched between the two tests; however, the Pluslife assay detected a higher proportion of D. immitis-positive samples (32.4%; 81/250) than the MK (30.0%; 75/250). There was no statistical significance between tests (p = 0.2113). Cohen's kappa statistic indicated almost perfect agreement between the two tests (0.85). Additionally, Acanthocheilonema reconditum was detected in 11 samples in the MK test, without generating false-positive results with the Pluslife assay, indicating its specificity. CONCLUSIONS: Our data suggest that the Pluslife Mini Dock D. immitis/D. repens duplex assay provides a novel diagnostic platform and is a suitable option for point-of-care MFDT.