The Africa Centres for Disease Control and Prevention (Africa CDC) has raised concern over an outbreak of an unidentified illness in Burundi (a small landlocked country in central-east Africa), where 35 cases and five deaths have been recorded since it was first detected on 30 March. The outbreak is concentrated in the Rugazi and Kibuye zones of Mpanda District, with cases spreading mainly within households and among close contacts; patients have presented with fever, vomiting, diarrhoea and headache, while severe cases show neurological signs and respiratory distress. Major viral haemorrhagic fevers including Ebola and Marburg have been ruled out, and a multisectoral rapid response team has been deployed as investigators continue to search for the cause using a One Health approach involving both human and animal health experts.