Having AIDS weakens the body's immune system. The immune system normally fights germs that enter the body. When AIDS makes it weak, it can't fight germs well. This can lead to serious infections that don't often affect healthy people. These are called opportunistic infections (OIs).There are many types of OIs. Tuberculosis and a serious related disease, mycobacterium avium complex (MAC) are bacterial infections. Viral infections include cytomegalovirus (CMV) and hepatitis C. Fungi cause thrush (candidiasis), cryptococcal meningitis, pneumocystis carinii pneumonia (PCP) and histoplasmosis, and parasites cause crypto (cryptosporidiosis) and toxo (toxoplasmosis). Having AIDS can make any infection harder to treat. People with AIDS are also more likely to suffer complications of common illnesses such as the flu. This new book presents the latest research in the field.