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Key Points

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  • A high index of suspicion is needed for the initial diagnosis of human immunodeficiency virus (HIV), particularly in the context of atypical presenting symptoms. Consider acute HIV in the patient who presents with a mononucleosis-like infection, but with negative monospot testing.

  • CD4 T-cell count is correlated with risk for opportunistic infection.

  • All patients with HIV and respiratory complaints, especially those with CD4 <200 cells/μL should be placed in negative pressure/airborne isolation until the diagnosis of tuberculosis can be excluded.

  • With appropriate care and proper management, people living with HIV can live a normal lifespan.

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Introduction

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Human immunodeficiency virus (HIV) is a cytopathic retrovirus that attacks the CD4 T-lymphocytes in the immune system. Acquired immunodeficiency syndrome (AIDS) occurs when HIV-induced loss of CD4 cells and the resulting immunosuppression permit infection from opportunistic pathogens. AIDS is defined as a CD4 count <200/μL, a CD4 percentage <14%, or the presence of an AIDS-defining illness. AIDS-defining illnesses include Pnemocystis jiroveci pneumonia (PCP), Mycobacterium tuberculosis (TB), toxoplasmosis, cryptococcosis, cryptosporidiosis, esophageal candidiasis, disseminated Mycobacterium avium complex (dMAC), and cytomegalovirus (CMV), among others.

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In the United States, approximately 1.2 million persons are infected with HIV, with up to 50,000 new cases every year. The estimated prevalence of HIV-positive patients seen in urban emergency departments (EDs) may be as high as 11.4%. Up to 20% of all HIV-positive persons in the United States are unaware of their HIV status.

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Risk factors for HIV acquisition include sexual activity, injection drug use, blood transfusion (particularly before screening of the donor pool commenced in 1985), intrapartum/neonatal exposure to a mother with HIV, and occupational exposure (break of skin with contaminated sharps or blood/body fluid splashes onto mucous membranes/non-intact skin).

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Acute retroviral syndrome (ARS) occurs in approximately 50% of acutely infected patients, approximately 2–4 weeks after exposure to HIV, and may clinically manifest as a flu-like or mononucleosis-like illness. Regardless of the presence or absence of ARS, most patients have a high viral load (>106 copies/cm3) during this period, and negative serologic tests. Seroconversion typically occurs 2–6 weeks (though sometimes up to 6 months) after exposure. An immune response to the virus is then generated, and the viral load falls to a setpoint with a relatively stable CD4 count. This leads to a period of clinical latency (usually 2–10 years) during which CD4 T-cells are continually destroyed and regenerated, and viral replication continues. Ultimately, immune control is ineffective, and the CD4 count falls, leading to increased susceptibility to opportunistic (as well as other) infection. Some CD4 cutoffs are associated with increased risk of certain infections (<200 with PCP, <100 with histoplasmosis, <50 with dMAC and CMV retinitis), but the clinician should be aware that infections may occur at a higher than anticipated CD4 levels.

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Clinical Presentation

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History

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All patients presenting to the ED with complaints of infections should be asked about their HIV status, if they have been tested, and about pertinent risk factors. Patients with unknown HIV status, significant risk factors, and symptoms consistent with an opportunistic infection should be assumed to be immunosuppressed. Patients with known HIV should be asked about their latest CD4 count, viral load, medications (including prophylaxis), and ...

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