When the immune system is very weak due to advanced HIV disease or AIDS, opportunistic infections such as PCP, toxoplasmosis and cryptococcosis develop.

• 晚期HIV疾病或艾滋病患者免疫系统非常脆弱，容易发生如卡式肺囊虫肺炎、弓形虫体病和隐球菌病等机会性感染。