Flooding and malaria in the Sahara: description of the 2024 outbreak in the Kidal region, Mali

Abstract Context During the 2024 rainy season, extreme rainfall events caused flooding in Mali, leading to an outbreak of malaria in the Kidal region of northern Mali. The aim of this study was to describe this epidemic and the response implemented by the national and regional authorities. Methods Weekly rainfall data (0.25° resolution) from TRMM and malaria cases from national health system. Data on SMCs and mobile clinics come from the national malaria control program. Malaria incidence and rainfall trends were analyzed, with the epidemic described according to severity and age group. The effects of the intervention were assessed using interrupted time series with a generalized additive model. Results Rainfall began in week 25 (June) and lasted 15 weeks, averaging 3.86 mm/day (CI95: 3.23–4.57). The malaria epidemic began in week 30, peaked at 1,014 cases in week 39, and lasted 28 weeks (incidence: 1.688/1,000 person-weeks; CI95: 1.687–1.690). The [0-11] months and [1-4] years age groups were the most affected, with respective incidences of 1.48 and 0.97 per 1000 person-weeks for severe cases, and 5.04 and 2.35 per 1000 person-weeks for uncomplicated cases. Two interventions were implemented: i) 2 SMC campaigns among children aged 0 to 4 years for the first round, and 0 to 10 years for the second round, during weeks 31 (July) and 41 (October) respectively (6,236 and 27,334 children respectively); ii) mobile teams deployed from week 34 (August) to 39 (September) in remote areas and Internally Displaced People (IDP) sites, with 35 members in addition to the 36 community health workers. These interventions significantly reduced morbidity, with respective SIRs of 0.5 CI95[0.33; 0.75] (p=0.002) and 0.48 CI95[0.28; 0.82] for SMC and mobile teams. Conclusion Climate change is increasing extreme weather events like floods, altering malaria risk in unstable areas such as northern Mali. Preparedness should include reinforcing community health workers, ensuring adequate diagnostic and treatment stocks, and deploying targeted mobile teams.