In its guidelines for the diagnosis, the WHO has included prevention and management of cryptococcal disease the cryptococcal antigen (CrAg) screening in severely immunocompromised patients (CD4 count <100 cells/mm3) as a strategy to prevent or detect at an early stage a significant number of meningitis cases, together with a preventive antifungal treatment [35]. The gene discussed is CD4; the disease is meningitis.