Malar J. 2026 Jan 27. doi: 10.1186/s12936-026-05795-2. Online ahead of print.
ABSTRACT
BACKGROUND: This study aimed to assess the community-based prevalence of malaria reservoirs following cases visiting health facilities. The diagnostic performance of microscopy in detecting community-based malaria parasites was compared to nested polymerase chain reactions (PCR).
METHODS: From July to October 2022, reactive case detection was conducted in Sile village, Gamo Zone, in the Southern Rift Valley of Ethiopia. Within six days of identifying an index case, all individuals in the same household and neighboring households were screened for malaria by microscopy, with nested PCR for confirmation. Asexual parasite and gametocyte density were measured microscopically.
RESULTS: Of the 2434 individuals visited following 142 PCR-confirmed index cases, 2009 were included in the final analysis. The PCR-corrected, microscopy-based malaria prevalence in the study community was 3.6% (72/2009; 95% CI 2.8-4.5). Subsequent PCR analysis of randomly selected microscopy-negative samples identified an additional 33 submicroscopic infections, yielding a submicroscopic prevalence of 10.1% (33/326; 95% CI 7.2-13.9). Submicroscopic prevalence was 4.6% for P. vivax (15/326; 95% CI 2.6-7.5) and 4.3% (14/326; 95% CI 2.4-6.9) for P. falciparum. Mixed infections comprised 1.3% (4/326; 95% CI 0.3-3.1) of the cases. Overall, submicroscopic infections accounted for 31% (33/105; 95% CI 22.6-40.8) of the total PCR-confirmed malaria cases in the community, indicating that nearly one-third were missed by microscopic examination. Index cases had higher asexual parasite density (16,177 vs. 1900/μL; P < 0.001) but lower gametocyte carriage than reactive cases, despite similar gametocyte densities (600 vs. 482/μL; P = 0.08). The gametocyte carriage rate was higher among P. vivax (22/32; 69%) than among P. falciparum (6/27; 22%) reactive cases.
CONCLUSION: The high gametocyte carriage rate among microscopy-reactive cases highlights the potential role of community-based infections in sustaining malaria transmission.
PMID:41593453 | DOI:10.1186/s12936-026-05795-2
