What STD affects the immune system?
HIV (human immunodeficiency virus) causes AIDS (acquired immunodeficiency disorder) by destroying T-cells in your immune system that fight off pathogens.
Although HIV (human immunodeficiency virus) can be spread through sexual fluids like semen and vaginal fluids, it can also be transmitted through blood and breast milk, so it is not strictly just a sexually-transmitted disease. However, it is the most common sexually-transmitted disease (STD) that affects the immune system, and HIV works by destroying special immune cells called T-cells.
T-Cell Count and AIDS:
HIV attacks the CD4 cells (also referred to as T-cells) in your immune system that help destroy pathogens. The estimated T-cell count in most humans ranges between T-cells counts between 500 - 1500. However, As HIV progresses, it can eventually destroy so many of these immune cells that the human body is unable to effectively kill pathogens, like viruses and bacteria. In people who have been effected severely by HIV, like famous basketball player Magic Johnson, this can result in a syndrome called AIDS (acquired immunodeficiency disorder), where T-cell count drops below 200. When this happens, the body is extremely susceptible to pathogens, and people with AIDS are extremely vulnerable to a variety of deadly diseases including tuberculosis, meningitis, and pneumonia.