Assessment and initial management of acute undifferentiated fever in tropical and subtropical regions

### What you need to know Acute undifferentiated febrile illnesses (AUFI) are characterised by fever of less than two weeks’ duration without organ-specific symptoms at the onset.1 These may begin with headache, chills, and myalgia. Later, specific organs may be involved. AUFIs can range from mild and self limiting disease to progressive, life threatening illness. A mortality rate of 12% has been reported in severely ill hospitalised patients in tropical regions.2 AUFIs are classified into malaria and non-malarial illnesses with the help of microscopy or rapid diagnostic tests for malaria.3 The overlap of epidemiological and clinical features often renders clinical diagnosis difficult. There is greater focus on non-malarial AUFIs with the decline of malaria in many regions of the world.4 They account for 20-50% of all fevers in children over 5 years of age and adults in Asia and Africa.5 Laboratory confirmation is difficult—in contrast to malaria and dengue, for which high accuracy rapid diagnostic tests are now available. Current guidelines do not comprehensively address undifferentiated infections, which can fuel indiscriminate use of antimalarials …