opportunistic infection

Opportunistic infections occur when normally harmless microorganisms become pathogenic due to a weakened immune system. This can happen when the immune system is compromised by factors such as immunosuppressive drugs used in organ transplantation, or by diseases like AIDS.123

In individuals with compromised immunity, organisms that typically do not cause illness can lead to serious conditions, such as pneumonia from cytomegalovirus or Pneumocystis infections. Fungal infections, like those caused by Candida, can also arise. These infections are often challenging to treat and can be fatal. The human immunodeficiency virus (HIV) is a prime example of a virus that causes a severe immune deficiency, leading to AIDS and making individuals susceptible to various opportunistic infections and cancers.243