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Undetected HIV infection


Figure 5-1.

Sequence of appearance of laboratory markers for HIV-1 infection. Approximately 10 days after infection, HIV-1 RNA becomes detectable by nucleic acid tests (NAT) in plasma and quantities increase to very high levels. Next, HIV-1 p24 antigen is expressed and quantities rise to levels that can be detected by fourth-generation immunoassays within 4–10 days after the initial detection of HIV-1 RNA. IgG become reactive 18–38 days or more after the initial detection of viral RNA. (Reproduced with permission from Centers for Disease Control and Prevention. Quick Reference Guide-Laboratory testing for the diagnosis of HIV infection: updated recommendations)

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).


  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 of HIV continues to increase in spite of the decreasing incidence because HIV-infected people live longer than in the past.

    4. The sex ratio of new HIV infections is about 4 males to 1 female.

    5. Men who have sex with men (MSMs) are disproportionately infected: male-to-male sexual contact accounts for 67% of new infections, heterosexual contact 24%, and injection drug use (IDU) 6%. About 3% of new infections are associated with both male-to-male sexual contact and IDU.

    6. Racial and ethnic disparities are significant: blacks account for 44% of new infections; whites, 26%; Hispanics, 25%; and Asians, 2%.

    7. Regional differences are also significant: the rates of new HIV diagnoses per 100,000 population are 16.8 in the South, 11.2 in the Northeast, 10.2 in the West, and 7.5 in the Midwest.

    8. Transmission

      1. Common modes of transmission include male-to-male sexual transmission, heterosexual transmission, and drug paraphernalia sharing among IDUs. Mother-to-child transmission ...

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