A 17 year old incarcerated male presented to our emergency department complaining of headache, nausea, vomiting, diarrhea, subjective fever and weight loss for one week. There were no sick contacts or recent travel. The patient had no prior medical history, and had tested negative for HIV six months before presentation. He was taking no medication and denied any family history. Sexual history revealed prior homosexual intercourse. On presentation, the patient's blood pressure was 99/44 mm/Hg with a temperature of 39.4 8C. Physical exam revealed seborrhea over the face and cervical, axillary and inguinal lymphadenopathy. Laboratory studies revealed a WBC count of 2,000, hematocrit of 48% and platelet count of 48,000. Urinalysis showed 2+ protein. Cerebrospinal fluid analysis, stool studies, and blood cultures were negative. Chest X-ray was normal. The patient underwent bone marrow aspiration, which revealed a hypoplastic marrow with decreased erythroid precursors, consistent with viral infiltration. The patient clinically improved and remained afebrile with resolution of all of his symptoms. His platelet count returned to normal. Parvovirus serologies were equivocal, and Epstein Barr serologies did not reveal acute infection. The patient underwent HIV testing which revealed a positive ELISA with an indeterminate Western blot. The CD4 count was 420. After consultation with the infectious disease team and the pathology department, we were permitted to perform viral load testing in the hopes of confirming the diagnosis of acute HIV infection. The viral load was greater than 750,000 copies per mL. DISCUSSION: Acute HIV infection presents with a variety of non-specific symptoms, including fever, lethargy, rash, myalgias and headache. Symptoms are present in 50 ± 90% of patients with acute infection, and the complex is known as acute antiretroviral syndrome. Because of the non-specific symptoms, acute HIV infection in adolescents often resembles, and may be mistaken for, more common viral illnesses such as infectious mononucleosis. The diagnosis should be suspected in any patient at risk for HIV infection who presents with this constellation of symptoms or fever of unknown cause. Early diagnosis of HIV, particularly during acute infection, is crucial so that antiretroviral therapy may be initiated without delay. The diagnosis is based on a HIV-1 RNA level of greater than 50,000 copies per mL or positive p24 antigen in the absence of a positive ELISA and confirmatory Western blot test for HIV. If a patient is HIV enzyme immunoassay-negative and HIV RNA-positive, follow-up antibody testing should be performed 2 ± 4 weeks after the resolution of symptoms to document seroconversion.