PCP has long been known for its high prevalence in acquired immunodeficiency deficiency syndrome (AIDS) patients [3], but the incidence of PCP in human immunodeficiency virus (HIV)-positive patients has been decreased largely due to the broader use of highly active antiretroviral therapy (HAART) and trimethoprim-sulfamethoxazole (TMP/SMZ) prophylaxis when the CD4+ T cell count is < 200/μL [4, 5]. This evidence concerns the gene CD4 and pneumocystosis.