The proportion of CD4-cell measurements <200 cells/mm3 where patients were receiving PCP prophylaxis was generally highest in Argentina in all three time periods (93%, 87% and 83% in < 2004, 2005–2006 and >2007, respectively) and lowest in Eastern Europe (57%, 41%, 38% in < 2004, 2005–2006 and >2007, respectively) (p < 0.0001) (Figure 3). The gene discussed is CD4; the disease is pneumocystosis.