Signs and symptoms of HIV are flu-like at first and may involve fever, headaches, joint pain and sore throat, notes Mayo Clinic. Fatigue, diarrhea, a non-itchy rash and swollen lymph nodes are also common. These symptoms may be quite mild and temporary, which often leads to an individual not realizing they have contracted the disease. After this initial stage, a person with HIV may be asymptomatic for years, but they can still pass the infection on to others.
Blood tests can determine whether the HIV infection is present by showing the presence of both the HIV antigen and HIV antibodies, but less sensitive tests may detect only the HIV antibodies. In later stages, blood tests can reveal the number of CD4 T-cells in the body, explains WebMD. A healthy individual has between 450 and 1,400 of these T-cells per microliter, and the amount fluctuates over time. These T-cell levels steadily drop in an individual infected with HIV. As they drop, the individual becomes more susceptible to other infections, including AIDs, which a doctor diagnoses when the T-cells drop below 200 per microliter. Untreated, HIV progresses to AIDs within approximately 10 years. Symptoms then include fever, soaking night sweats, diarrhea, white spots in the mouth and on the tongue, fatigue, and unexplained weight loss.