Management of children with prolonged fever of unknown origin and difficulties in the management of fever of unknown origin in children in developing countries.

This is Part II of a 2-part paper on fever of unknown origin (FUO) in children. It examines the aetiology and management of prolonged FUO in children and the difficulties in the management of FUO in children in developing countries. Part I of this paper discussed acute FUO in children and was published in the March 2001 issue of Paediatric Drugs. Prolonged FUO is documented fever of more than 7 to 10 days which has no apparent source and no apparent diagnosis after 1 week of clinical investigations. About 34% of cases of prolonged FUO are caused by infections, with bacterial meningitis and urinary tract infection accounting for about 6.5 and 11.4%, respectively, of cases attributable to infections. Chronic infections, particularly tuberculosis and 'old' disorders such as Kawasaki disease, cat-scratch disease and Epstein-Barr virus infection presenting with 'new' manifestations, collagen-vascular diseases and neoplastic disorders are the other issues of major concern in prolonged FUO. Overall, however, there is a trend towards an increased number of undiagnosed cases. This is due to advancements in diagnostic techniques, such that illnesses which were previously common among the causes of prolonged FUO are now diagnosed earlier, before the presentation becomes that of prolonged FUO. Clinical examination supplemented with laboratory tests to screen for serious bacterial infections should be the mainstay of initial evaluation of children with prolonged FUO. Use of scanning techniques (such as computerised tomography and ultrasound) as additional supplements to this clinical examination may allow for the earlier diagnosis of causes of prolonged FUO in children such as 'occult' abdominal tumours. A common error in management of children with prolonged FUO is the failure to perform a complete history and physical examination; repeated clinical examination and continued observation are of paramount importance in the diagnosis of difficult cases. Major difficulties in the management of FUO in children in developing countries include constraints in the availability and reliability of laboratory tests, cost, misuse of antibiotics and difficulties encountered in the diagnosis of malaria and typhoid fever. Malaria and typhoid fever are major aetiological considerations in both acute and prolonged FUO in children in developing countries. The newer quinolones may hold great promise for the treatment of serious bacterial infections, including meningitis, which are associated with prolonged FUO in developing countries.