Mycobacterium avium complex (MAC) is a group of bacteria, commonly found in soil or water, that can infect people who have acquired immunodeficiency disease (AIDS). In people whose CD4+ cell count drops below 50 cells per microliter (mcL), the bacteria can spread throughout the body and cause infection almost anywhere.

Symptoms include:

• Night sweats.
• Fever.
• Diarrhea.
• Fatigue.
• Weight loss.
• Belly pain.

There is no easy way to avoid exposure to Mycobacterium avium complex bacteria. But medicines are available that can prevent disease.