cross-sectional survey of Plasmodium falciparum and Plasmodium vivax in India using rapid diagnostic test and microscopy across 12 sites of varying transmission, 2023-2024.

BackgroundIn India, Plasmodium falciparum and Plasmodium vivax remain in circulation. Accurate detection of the parasite species remains crucial for prompt initiation of treatment and reducing onward transmission.MethodsA cross-sectional study across 12 sites of varying malaria endemicities was conducted from September 2023 to April 2024. Febrile participants were tested for malaria using rapid diagnostic tests (RDTs) and microscopy. Malaria positivity proportions along with 95% confidence intervals (95% CI) were presented separately by parasite species. The diagnostic performance of the RDT was compared against microscopy.ResultsA total of 10,290 febrile participants were tested by both RDT and microscopy: 1,516 (14.7%, 95% CI 7.7-21.8%) malaria cases were identified by RDT and 1,436 (14.0%, 95% CI 6.9-21.1%) by microscopy. Of the 1,516 RDT positives, 1,105 (72.9%) had P. falciparum mono-infection, 290 (19.1%) had P. vivax mono-infection, and 121 (8.0%) had P. falciparum and P. vivax mixed infections. The sensitivity and specificity of RDT were 95.0% [95% CI 94-96%] and 99% [95% CI 98-99%], respectively, for detecting P. falciparum mono-infection, 83% [95% CI 78-87%] and 100% [95% CI 99-100%] for detecting P. vivax mono-infection, and 88% [95% CI 80-93%] and 100% for detecting a mixed infection of P. falciparum and P. vivax. Overall, 43 (0.4%) participants who were RDT negative were found to have malaria on subsequent microscopic examination.ConclusionApproximately 15% of the febrile participants tested were identified as malaria positive by RDT, of which nearly one-fifth were P. vivax mono-infections and 8% harboured P. falciparum and P. vivax mixed infections. Low sensitivity of the RDTs for identifying P. vivax underscores an urgent need for developing reliable diagnostics.