The document discusses HIV/AIDS, caused by the human immunodeficiency virus (HIV). HIV is a retrovirus that infects and destroys cells of the immune system, specifically T-cells, weakening the immune system and allowing opportunistic infections. Symptoms of HIV/AIDS include weight loss, diarrhea, mental disorders, vision problems, and tiredness. HIV can be transmitted sexually, through blood or needles, or from mother to child. Diagnosis involves blood tests that detect HIV antibodies, such as ELISA and Western Blot tests. Prevention includes safe sex practices, not sharing needles, avoiding tattoos with infected needles, and comprehensive sex education.