Acute HIV infection

Overview
Acute HIV infection or primary HIV infection is the first stage of HIV infection. It occurs before the latency stage and the potential AIDS succeeding the latency stage.

Symptoms
During this period (usually 2-4 weeks post-exposure) most individuals (80 to 90%) develop influenza or mononucleosis-like symptoms, most commonly fever, lymphadenopathy, pharyngitis, generalized rash of maculopapular type, myalgia, malaise, mouth and esophagal sores, and may also include, but less commonly, headache, nausea and vomiting, enlarged liver/spleen, weight loss, thrush, and neurological symptoms. Infected individuals may experience all, some, or none of these symptoms. The duration of symptoms varies, averaging 28 days and usually lasting at least a week. Because of the nonspecific nature of these symptoms, they are often not recognized as signs of HIV infection. Even if patients go to their doctors or a hospital, they will often be misdiagnosed as having one of the more common infectious diseases with the same symptoms. Consequently, these primary symptoms are not used to diagnose HIV infection as they do not develop in all cases and because many are caused by other more common diseases. However, recognizing the syndrome can be important because the patient is much more infectious during this period.

Cause
It is a period of rapid viral replication that immediately follows the individual's exposure to HIV leading to an abundance of virus in the peripheral blood with levels of HIV commonly approaching several million viruses per mL. This response is accompanied by a marked drop in the numbers of circulating CD4+ T cells. This acute viremia is associated in virtually all patients with the activation of CD8+ T cells, which kill HIV-infected cells, and subsequently with antibody production, or seroconversion. The CD8+ T cell response is thought to be important in controlling virus levels, which peak and then decline, as the CD4+ T cell counts rebound to around 800 cells per mL (the normal value is 1200 cells per mL ). A good CD8+ T cell response has been linked to slower disease progression and a better prognosis, though it does not eliminate the virus. A strong immune defense reduces the number of viral particles in the blood stream, marking the end of the acute HIV infection and the start of the infection's clinical latency stage, which, in turn, may be succeeded by true AIDS.