Infectious mononucleosis and mononucleosis-like illnesses in children and adults in Saudi Arabia.

The diagnosis of heterophil antibody positive, heterophil negative infectious mononucleosis and mononucleosis-like illnesses as made in 58 children and adult patients with clinical features suggestive of the mononucleosis syndrome and significant number of atypical lymphocytes. Epstein-Barr virus (EBV) specific serological tests revealed that six children and 23 adults had primary heterophil positive EBV infections based on the detection of IgM to EB-viral capsid antigens (IgM-VCA), presence of IgG to DB-early antigens (EA-D) and absence of antibodies to EB-nuclear antigen (EBNA). A further nine cases (five children, four in adults) of heterophil negative EBV infectious mononucleosis were likewise detected by EBV-specific serologic tests. Fourteen cases including one in children were due to active cytomegalovirus (CMV) infections as evident by positive CMV-IgM; they were all heterophil negative. Of the remaining heterophil negative cases, one was due to T. gondii with positive Toxo-IgM and five cases were of undetermined aetiology.