Estimating the burden of imported malaria in the Asia Pacific region: a systematic review and meta-analysis

BACKGROUND: Imported malaria is a major barrier to achieve and sustain malaria elimination for countries in Asia Pacific. This systematic review and meta-analysis quantified the pooled prevalence of imported malaria in the region. METHODS: The systematic review and meta-analysis protocol was registered in PROSPERO (CRD420251008817). Three databases including PubMed, Scopus, and Web of Science were used for literature search from 1 January 2010 to 31 December 2024 for imported malaria in 22 Asia Pacific malaria eliminating countries. Pooled prevalence with 95% confidence intervals (CI) was calculated using an inverse variance random-effects meta-analysis. Heterogeneity, sensitivity analysis, and publication bias were also assessed. RESULTS: Based on 42 studies conducted in nine Asia Pacific countries with a total of 435,454 malaria cases, the pooled prevalence of imported malaria was 89.0% (95% CI: 75.9-95.5, I2-100%, n =166,412 imported cases). The pooled prevalence of imported malaria in males, Plasmodium falciparum, and origin from Africa was 94% (95% CI: 92.0-96.0, I2-97.5%, n = 70,619), 57.0% (95 % CI: 47.2-65.5, I2-99.5%, n=60,999), and 64.3% (95 % CI: 43.1-81.0, I2-99.5%, n = 67,511), respectively. The imported malaria varied by occupation with 53.0% (95% CI: 34.0 -71.0, I2-99.7%, n = 7,989) in labourer to 40.0% (95% CI: 15.0-72.0, I2-99.7%, n = 9,611) in farmers. The subgroup meta-analysis revealed pooled prevalence of 84.6% (95% CI: 68.3 - 93.3, I2 -100% n=154,792) in pre-elimination phase, and it ranged between 95.0% in Sri Lanka (95% CI: 13.0-100, n=761) and China (95% CI:85.8-98.0, n = 156,031) to 3.2% (95% CI: 2.87-3.47, n = 407) in South Korea. CONCLUSION: Imported malaria constitutes a significant proportion of malaria cases in Asia Pacific malaria eliminating countries. The findings highlight the critical need for strengthened cross border coordination for surveillance, and tailored interventions to achieve and sustain malaria elimination efforts in the region.