Malaria parasite prevalence among migrants: a systematic review and meta-analysis

Background: Asymptomatic malaria infections are highly prevalent in endemic areas.

Objectives: This systematic review aimed to estimate the pooled prevalence of malaria parasites in migrants screened in non-endemic areas.

Data sources: MEDLINE-Ovid, EMBASE, Web of Science, Global Health, Lilacs, Cochrane, and MedRxiv.

Study eligibility criteria: Cross-sectional studies and observational prospective or retrospective cohort studies conducted in Europe, USA, Canada, Australia, or New Zealand regardless of language or publication status. Studies should include prevalence data on malaria in migrants that were recruited through a systematic screening approach. We excluded studies where people were tested because of malaria symptoms.

Participants: Migrant individuals exposed to malaria infection ASSESSMENT OF RISK OF BIAS: A standardized and validated appraisal instrument was used for studies reporting prevalence data (Joanna Briggs Institute Manual for Evidence Synthesis).

Methods of data synthesis: Pooled estimates of the parasite prevalence by PCR, microscopy, and rapid diagnostic test (RDT) were calculated with a random-effects model. Heterogeneity was explored by stratification by age, region of origin, period of study, and quality of studies.

Results: Of 1819 studies retrieved, 23 studies were included with in total 4203 participant PCR data, 3186 microscopy and 4698 RDT data, respectively. Migrants from sub-Saharan Africa had a malaria parasite prevalence of 8.3% (95% CI 5.1-12.2) by PCR, 4.3% (1.5-8.2) by RDT, and 3.1% (0.7-6.8) by microscopy. For migrants from Asia and Latin America, the prevalence with PCR was 0% (0.0-0.08) and 0.4% (0.0-1.8), respectively. Migrants from the Central African Region had the highest PCR prevalence (9.3% [6.0-13.0]), followed by West African migrants (2.0% [0.0-7.7]). Restricting the analysis to sub-Saharan Africa migrants arriving to the host country within the previous year, the PCR-based prevalence was 11.6% (6.9-17.4).

Conclusion: We provide estimates on the malaria parasite prevalence in migrants in non-endemic setting. Despite heterogeneity between settings, these findings can contribute to inform screening strategies and guidelines targeting malaria in migrants.