Human Immunodeficiency Virus (HIV) Infection

Key Features

Essentials of Diagnosis

• Infants with in utero HIV infection have virus detectable in the blood at birth

• Those infected peripartum test negative for virus at birth but have virus detected by 2–4 weeks of age

• Infant viremia rises steeply, reaching a peak at age 1–2 months

• Infants have a gradual decline in plasma viremia that extends to age 4–5 years

• Up to 50% of infants will have rapid disease progression to AIDS or death by age 2 years

General Considerations

• Infection results in profound effects on both humoral and cell-mediated immunity

• In the absence of treatment, HIV infection causes generalized immune incompetence

• Clinical diagnosis of AIDS is made when severe opportunistic illnesses develop in an HIV-infected individual, such as

  • Candidiasis of bronchi, trachea, lungs, or esophagus

  • Disseminated or extrapulmonary histoplasmosis

  • Kaposi sarcoma

  • Disseminated or extrapulmonary Mycobacterium avium complex

  • Wasting syndrome

• In children older than 6 years, the criteria for a diagnosis of AIDS also include an absolute CD4 T-lymphocyte count of 200 cells/μL or less

Demographics

• Among children younger than 15 years, there were 220,000 new infections and 150,000 deaths in 2014

• High rates of new pediatric infections are the result of ongoing mother-to-child transmission (MTCT) in resource-limited settings where access to preventative measures is often not accessible

  • Transmission occurs in utero, at the time of labor and delivery (peripartum), or during breast-feeding (postnatal transmission)

  • However, MTCT can be reduced to less than 1–2% with prenatal, perinatal, and postnatal interventions

• Occupational exposure resulting from accidental needle sticks or, rarely, mucosal exposure to blood may occur

Clinical Findings

• Newborns with perinatal HIV infection rarely have symptoms or physical examination findings at birth, and there is no recognized primary infection syndrome in infants

• However, symptoms develop in 30–80% of infected infants within the first year of life

• Signs associated with slow progression include

  • Hepatomegaly

  • Splenomegaly

  • Lymphadenopathy

  • Parotitis

  • Recurrent respiratory tract infections

• Severe bacterial infections, progressive neurologic disease, anemia, and fever are associated with rapid progression

• Children with HIV are at increased risk of malignancy; most commonly occurring tumors are non-Hodgkin lymphomas

Diagnosis

Laboratory Findings

• Infants born to HIV-infected mothers will have transplacental maternal HIV antibody regardless of their infection status

• The median time to seroreversion is 13.9 months and most uninfected infants become antibody negative by 18 months; in a minority of infants, however, maternal antibody is detected until age 24 months

• The preferred test for infant diagnosis is detection of HIV nucleic acid (DNA or RNA) in blood

• Positive HIV nucleic acid testing (NAT) at any age requires a subsequent sample for confirmation to rule out a false positive

• The hallmark of HIV disease progression is decline in the absolute number and percentage of CD4 T lymphocytes and an ...