**5.2. Opportunistic infections**

An opportunistic infection is an infection caused by pathogens, particularly opportunistic pathogens, such as bacterial, viral, fungal or protozoal infections that usually do not cause disease in a healthy host with a healthy immune system. All HIV-infected individuals are in the immunosuppressive state. They are susceptible to a wide array of opportunistic infections and are at higher risk to pathogenic organisms that plague the general population [65]. Infectious agents reported to attack the bone marrow in patients with HIV include Mycobac‐ terium avium complex, Mycobacterium tuberculosis, Mycobacterium xenopi and kansasi, Histoplasma, Cryptococcus, Toxoplasma, Cytomegalovirus and Pneumocystis carinii [66]. These infections may cause marrow changes either directly by the the organism itself or indirectly by causing reactive changes.
