A CD4 count of less than what number is indicative of AIDS?

A CD4 count of less than 200 cells/mm³ is a key indicator for diagnosing AIDS (Acquired Immunodeficiency Syndrome). The CD4 cell count measures the number of CD4 T lymphocytes in the blood, which are crucial for the immune system's ability to fight off infections. Normal CD4 counts typically range from 500 to 1,600 cells/mm³. When the CD4 count falls below the threshold of 200, it signifies a significantly weakened immune system, placing the individual at high risk for opportunistic infections and certain cancers, which are characteristic of AIDS.

This threshold plays an essential role in determining when a person with HIV progresses from being classified as having HIV to having AIDS, a more severe and life-threatening stage of the infection. Maintaining awareness of this critical CD4 count can help in monitoring and managing HIV-related health issues effectively.