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How do I diagnose or exclude HIV infection?



Mr. A asks his new primary care clinician whether he should get an HIV test. He states that he has “absolutely no risk factors for HIV,” and is a very healthy 21-year-old black man in a monogamous relationship with his girlfriend for 2 years. The girlfriend was tested for HIV 6 months ago when a Board of Health nurse notified her that she might have been exposed to HIV, and retested 3 months ago. Both HIV tests were negative, effectively ruling out HIV infection.

Mr. A first became sexually active at age 15. Over the last 6 years, he has had 4 female partners, with a bit of overlap between the relationships (he had 2 simultaneous partners for about 1 year). He has never had sex with a male. He uses condoms “pretty consistently.” He had Chlamydia trachomatis urethritis 3 years ago, but no other sexually transmitted infections. He has never used injecting drugs, although he smokes marijuana once or twice a week. He stopped drinking excessively when he met his current girlfriend. He does not recall an episode of mononucleosis-like illness with fever and lymph node enlargement. His past medical history, review of systems, and physical exam are otherwise unremarkable.

image Is the clinical information sufficient to make a diagnosis? If not, what other information do you need?

Leading Hypothesis: Undetected HIV infection

Textbook Presentation

Chronic HIV infection may present in a myriad of ways. Many patients are entirely asymptomatic in spite of long-standing HIV infection and advanced immune deficiency as demonstrated by an absolute CD4 T lymphocyte (CD4TL) count below 200 cells/mcL (immunologic AIDS). Some patients may have symptoms that are often seen with HIV but are nonspecific, such as chronic diarrhea, seborrheic dermatitis, multiple molluscum contagiosum, poorly responsive psoriasis, and prurigo nodularis. Other patients have conditions that are strongly associated with HIV infection but are also encountered in non–HIV-infected persons, such as tuberculosis (TB), idiopathic thrombocytopenic purpura, nephropathy, nonischemic cardiomyopathy, herpes zoster (shingles), and non-Hodgkin lymphoma. Unfortunately, patients may be found to have HIV only when they are admitted to the hospital with a life-threatening AIDS-defining condition, such as Pneumocystis jirovecii pneumonia (PJP), Cryptococcus neoformans meningitis, central nervous system (CNS) toxoplasmosis, or primary CNS lymphoma (PCL).

Disease Highlights

  1. Epidemiology of HIV in the United States

    1. Prevalence: At the end of 2016, the Centers for Disease Control and Prevention (CDC) estimated that 1,130,000 persons were living with HIV infection in the United States of whom 973,846 persons had been diagnosed (an 11% increase over 2011).

    2. Incidence: In 2016, there were 39,782 new HIV diagnoses, a 5% decrease from 2011.

    3. The prevalence ...

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