According to AIDS.gov, many people who contract HIV do not experience any significant symptoms related to the disease upon first contracting it. However, about 40 to 90 percent of infected persons experience acute flu-like symptoms during the first two to four weeks after contraction. This is formally called acute retroviral syndrome.
According to AIDS.gov, the flu-like symptoms reported with ARS are often severe, with many likening it to the "worst flu ever." ARS, or what is also known as primary HIV infection, is thus the body's first immune response to the presence of the virus in the system. Symptoms include significant fever, swollen glands, rash, fatigue, muscle and joint aches, headache and sore throat. Duration of these symptoms varies but can last from days to weeks, depending on the individual. It is important for the individual not to panic if he experiences any of these symptoms or clusters of them, as each can be caused by a variety of other illnesses.
Additionally, AIDS.gov claims that many infected persons can go up to 10 years before exhibiting any symptoms of infection whatsoever. The same source advises anyone who believes herself to have recently risked exposure to the virus to contact her physician to arrange for testing, regardless of whether or not she displays any of the aforementioned symptoms. As of 2013, a test is available that can detect the disease in its earliest stages, even before the body produces antibodies to counteract it. Former diagnoses had depended on the isolation of that antibody.