Pediatric AIDS patients present a diagnostic dilemma due to the subtle and insidious manifestation as well as higher CD4 counts; therefore prophylaxis guidelines in children are based on the characteristics of the infection in infancy of the age and specific changes in the CD4 cell count. Institution parameters for starting dideoxynucleosides include clinical manifestations (eg, an AIDS-defining infection, failure to thrive, progressive encephalopathy from HIV, AIDS-associated malignancy, two or more episodes of meningitis) and laboratory indications (eg, CD4 counts, thrombocytopenia, hypogammaglobulinemia).