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Chapter 40: Human Immunodeficiency Virus Infection

INTRODUCTION

  • Table 40–1 presents the case definition for adult, adolescent, and children, respectively, for human immunodeficiency virus (HIV) infection.

TABLE 40–1Surveillance Case Definition for HIV Infection Stage Based on CD4+ T-lymphocyte Counts, United States, 2014
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TABLE 40–1 Surveillance Case Definition for HIV Infection Stage Based on CD4+ T-lymphocyte Counts, United States, 2014
Age on date of CD4+ T-lymphocyte test
<1 year 1–5 years ≥6 years
Stage Cells/μL (×106/L) % Cells/μL (×106/L) % Cells/μL (×106/L) %
1 ≥1500 ≥34 ≥1000 ≥30 ≥500 ≥26
2 750–1499 26–33 500–999 22–29 200–499 14–25
3 (AIDS) <750 <26 <500 <22 <200 <14
AIDS indicator conditions
Bacterial infections, multiple or recurrent (specific to children <6 years)
Candidiasis of bronchi, trachea, or lungs Lymphoma, Burkitt
Candidiasis, esophageal Lymphoma, immunoblastic
Cervical cancer, invasive (specific to adults, adolescents, children >6 years) Lymphoma, primary, or brain
Coccidioidomycosis, disseminated or extrapulmonary Mycobacterium avium complex or Mycobacterium kansasii, disseminated or extrapulmonary
Cryptococcosis, extrapulmonary Mycobacterium tuberculosis, any site (pulmonary or extrapulmonary)
Cryptosporidiosis, chronic intestinal (duration >1 month) Mycobacterium, other species or unidentified species, disseminated or extrapulmonary
Cytomegalovirus disease (other than liver, spleen, or nodes), onset at age > 1 month Pneumocystis jirovecii pneumonia (PCP)
Cytomegalovirus retinitis (with loss of vision) Pneumonia, recurrent (specific to adults, adolescents, children >6 years)
Encephalopathy, HIV-related Progressive multifocal leukoencephalopathy
Herpes simplex: chronic ulcer(s) (duration >1 month); or bronchitis, pneumonitis, or esophagitis, onset at age > 1 month

Salmonella septicemia, recurrent

Toxoplasmosis of brain, onset at age >1 month

Wasting syndrome due to HIV
Histoplasmosis, disseminated or extrapulmonary Isosporiasis, chronic intestinal (duration >1 month) Kaposi’s sarcoma

ETIOLOGY AND PATHOGENESIS

  • Infection with HIV occurs through three primary modes: sexual, parenteral, and perinatal. Sexual intercourse, primarily anal and vaginal intercourse, is the most common vehicle for transmission. The highest risk appears to be from receptive anorectal intercourse at about 1.4 transmissions per 100 sexual acts. Condom use reduces the risk of transmission by approximately 80%. Individuals with genital ulcers or sexually transmitted diseases are at great risk for contracting HIV.

  • The risk of HIV transmission from sharing needles is approximately 0.67 per 100 episodes.

  • Healthcare workers have a small risk of occupationally acquiring HIV, mostly through accidental injury, most often percutaneous needlestick injury.

  • Perinatal infection, or vertical transmission, is the most common cause of pediatric HIV infection. The risk of mother-to-child transmission is ~25% in the absence of antiretroviral therapy. Breast-feeding can also transmit HIV.

CLINICAL PRESENTATION AND DIAGNOSIS

  • Clinical presentations of primary HIV infection vary, but patients often have a viral syndrome or mononucleosis-like illness with fever, pharyngitis, and adenopathy (Table 40–2). Symptoms may last for 2 weeks.

  • Most children born with HIV are asymptomatic. On physical examination, they often present with unexplained physical signs such as lymphadenopathy, hepatomegaly, splenomegaly, failure to thrive, weight ...

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