Quantifying the role of importation on sustained malaria transmission in a low-to-moderate burden region of Southwest Uganda.
prospective_cohort · Level II
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- Record sourced from PubMed, PMID 41493902.
- Also identified by DOI 10.1093/infdis/jiag008.
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Abstract
Parasite importation remains a challenge to malaria elimination. The extent to which human travel contributes to sustained transmission in low-to-moderate burden areas of endemic African countries is poorly understood. We conducted a 14-month longitudinal cohort study in Kamwezi subcounty, Southwest Uganda, an area targeted for malaria elimination. A total of 1,918 individuals from 400 households were followed bi-monthly. Travel histories and household characteristics were collected through structured surveys. Incident symptomatic and asymptomatic Plasmodium falciparum infections were captured through health facility surveillance and household reports (for symptomatic cases) and qPCR (for asymptomatic infections). Multilevel logistic regression models estimated associations between overnight travel and incident infection, adjusting for demographic and household factors. Population attributable fractions (PAF) quantified travel's contribution to malaria, stratified by transmission intensity, season, and village. Over the study period, 283 infections (244 symptomatic episodes and 39 asymptomatic infections) were recorded. Nearly one-third of participants reported at least one overnight trip. Associations between travel and malaria varied spatially and temporally, with positive associations in lower transmission villages OR = 4.38, 95% CI 1.80-10.64) and during periods of low transmission. Associations were strongest for short-distance trips to nearby areas of higher incidence. PAF analyses suggested travel accounted directly for 14% of malaria cases in low-transmission villages overall, rising to 30% during periods of low transmission. Overnight travel contributed meaningfully to malaria burden, particularly in low-transmission villages and during low seasons. These findings highlight the need for surveillance and control strategies that address both local transmission and importation.