The signs and symptoms of HIV infection and AIDS vary depending on the genetic background and age of the individual, and whether he or she has access to medical treatment.

Most HIV-positive individuals experience a sharp reduction in immune system responses, which increases vulnerability to an array of bacteria, viruses, parasites, and fungi. This vulnerability can result in “opportunistic” infections, or infections that do not normally occur in individuals with healthy immune systems.

The early stages of HIV infection are sometimes symptom-free, but most patients experience flu-like symptoms such as…