Co-trimoxazole for childhood febrile illness in malaria-endemic regions. The efficacy of co-trimoxazole for the treatment of Plasmodium falciparum parasitaemia in children younger than 5 years of age was evaluated in Malawi. 46 children with P falciparum parasitaemia, 37% of whom also met clinical criteria for a diagnosis of acute lower respiratory tract infection, were treated with 20 mg/kg co-trimoxazole twice daily for five days. Parasitaemia (mean clearance time 2.7 days) and symptoms were rapidly abolished and improvement was maintained during follow-up for 14 days. Co-trimoxazole may be an effective single treatment for febrile illness in young children in areas where malaria is endemic, resources are few, and diagnosis must rely on clinical findings alone. 