Imported mosquito-borne infectious diseases in travellers and migrants: Global patterns, clinical overlap, and prevention gaps-an umbrella review of 21 systematic reviews.

BACKGROUND

Imported mosquito-borne infectious diseases (MBIDs) pose public health challenges in nonendemic regions, but cross-disease evidence remains fragmented. We conducted an umbrella review of systematic reviews to identify gaps and inform clinical practice and research priorities.

METHODS

Five databases (PubMed, Embase, Scopus, Web of Science, and the Cochrane Library) were searched from inception to December 3, 2025, for systematic reviews on nine imported MBIDs, including chikungunya, dengue, Rift Valley fever, yellow fever, Zika, lymphatic filariasis, malaria, Japanese encephalitis, and West Nile fever. Only English-language publications were included. Epidemiological, clinical, and prevention data were extracted; methodological quality was assessed using AMSTAR 2; and evidence gaps were examined through bibliometric mapping.

RESULTS

Of the 2,610 references, 21 systematic reviews were included, resulting in the synthesis of 1,946 studies from 1943 to 2025 across seven of the nine prespecified imported MBIDs. No eligible systematic reviews were identified for Japanese encephalitis or West Nile fever. Dengue had the most importation evidence mainly from Asia, with 42,264 European cases. Malaria had migration flows from West Africa and India. Yellow fever, Rift Valley fever, and lymphatic filariasis were rarely reported, although one migrant-focused review reported 2,449 filariasis cases in Europe. Clinical presentations, particularly fever, myalgia, and rash, overlapped. Severe malaria fatality was 5.1% (95% confidence interval [CI] 4.0-6.2%), dengue fatality was 0.08-12.5%, and yellow fever fatality was 28.6%. Only five reviews addressed prevention. The evidence was uneven: 66.4% of the studies were conducted in Europe and 0.6% in Africa; dengue and malaria dominated the output; and Rift Valley fever accounted for <1% of all studies. Methodological quality was critically low in 66.7% of the reviews and high in 9.5%.

CONCLUSIONS

The evidence base for imported MBIDs reveals major asymmetries across diseases, outcomes, geographies, and populations, limiting evidence-based management of viral MBIDs, sustaining reliance on symptom-based approaches, and overlooking vulnerable populations.