ABSTRACT
Viral infections are usually benign, self-limited and of short duration and are then a rare cause of Unexplained Fever (U.F.). The Epstein-Barr virus (EBV) infection has protean manifestations, distinct from Infectious mononucleosis, and more common in childhood. In contrast with EBV, the cytomegalovirus (CMV) diseases which can be associated with U.F. seem to be more frequent in adults. In the immunodepressed patients, CMV disease evolves as a severe prolonged febrile illness with various complications. Infections are caused by organisms morphologically similar and closely related by taxonomy: both are actinomycetes, higher bacteria. The diagnosis relies on bacteriologie and more particularly on histologic examinations. Bacteriologie demonstration is the usual mode of diagnosis. N. asteroides grows slowly on aerobic-enriched media for bacteria or for fungi. Cell wall-deficient bacteria, or L-forms, or microbial spheroplasts, have atypical morphologic forms because they are derived from parent bacteria that have lost their rigidity owing to defective cell wall.
