 Each time a study participant is seen in the clinic a standardized history and physical exam will be performed. Patients who are febrile tympanic temperature 3 8.0 C or report history of fever in the past 24 hours will have blood obtained by finger prick for a thick blood smear. If the thick blood smear is positive, the patient will be diagnosed with malaria. If the thick blood smear is negative, the patient will be managed by study physicians for a non-malarial febrile illness. If the patient is afebrile and does not report a recent fever, a thick blood smear will not be obtained, except when following routine testing schedules. 