The acute phase of HIV does not necessarily result in a low-grade fever. Only some patients develop clinical symptoms about 2-4 weeks after initial HIV infection due to HIV viremia and acute damage to the immune system. The most common of these symptoms is fever, and the fever is predominantly low, usually not exceeding 38°C, but most of these symptoms will resolve on their own in about 1-3 weeks. Therefore, if a patient develops a low-grade fever within 4 weeks after a high-risk behavior, it is not possible to diagnose HIV infection by a low-grade fever, because fever is not specific and many diseases can cause fever. To confirm the diagnosis of AIDS, the patient’s blood should be tested for HIV antigen antibodies to determine if the infection is present.