Temporal and spatial patterns of malaria in Somalia, 2021-2025: a district-level analysis of routine surveillance data.

BACKGROUND

Malaria has increased across the Horn of Africa, where invasive urban mosquito vectors have been established. Somalia's sub-national epidemiology, surveillance completeness, and care cascade have not been evaluated in recent years.

METHODS

Routine national malaria surveillance data for Somalia from 2021-2025 were analyzed using a retrospective observational design, organized as a district-level annual panel of the same administrative units observed repeatedly each year. All 20 regions and 125 district reporting units were included, yielding 625 district-year records. Test positivity, annual parasite index, treatment coverage, and reporting completeness were calculated by reporting area and year, and the 2024 increase was disaggregated into testing and positivity components against the means for 2021 to 2023.

RESULTS

Confirmed cases remained near 13,000 per year from 2021-2023, rose to 32,030 in 2024, and then fell to 25,586 in 2025. The 2024 figure was 142.8% above the 2023 figure, while testing rose by only 8.9%, and test positivity rose from 4.3% to 9.5%. Nine neighboring north-western districts contributed 14,238 cases (90.0% of the district-level increase of 15, 828), with Borama alone contributing 47.7%. Cases treated without a parasitological test fell from 26,493 in 2021 to none, and reporting completeness rose from 76.1% to 99.9%.

CONCLUSION

The 2024 increase appears to reflect a genuine rise in transmission concentrated in north-western Somalia rather than wider testing alone. Expanding entomological surveillance for invasive vectors, aligning vector control with district-level burden, and improving data quality on parasite species and disease severity are urgent priorities for the disease.