The preliminary investigations of prolonged fever of unknown origin (FUO) in primary health care are ESR, full blood count and CRP urinalysis and bacterial culture imaging studies (chest x-ray, maxillary sinus imaging). If the blood picture is normal, CRP and ESR within normal limits and the fever is fluctuating and of low grade, a specific underlying cause is only rarely found. In these cases, fever gradually resolves in over 80% of children and no definite diagnosis is necessarily ever made . If the cause of fever remains unknown, the blood picture has abnormal features, the inflammatory markers are elevated or empiric antimicrobials are considered, investigations are continued in specialist health care. Fever in infants under the age of 3 months requires urgent management .