Page 255 - AIDSBK23C

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PEDIATRIC AIDS

Pediatric HIV infection is primarily acquired perinatally. Infection can occur in utero
prior to birth, intrapartum during delivery, or via breast milk following delivery.[181] Pediatric
HIV infections acquired through transfusion of blood or blood products are rare in places where
adequate testing programs for these products are in place. Sexual abuse of children may also be
identified as a risk factor in some cases. In adolescents aged 13 to 19, the manner of presentation
and the nature and appearance of opportunistic infections and neoplasms seen with AIDS is
similar to adults.[1038]

DIAGNOSIS.-- The diagnosis of HIV infection in children <18 months of age is
complicated because passively acquired maternal HIV antibody may be present, so tests for HIV
antibody alone are not sufficient, and additional criteria are necessary.[390,391] About half of
HIV-infected infants do not have detectable HIV by laboratory methods within the first month of
life, but in virtually all cases HIV infection can be established at 1 to 2 months of age. The most
sensitive method for HIV detection is HIV viral culture, but this is not practical. HIV RNA
assay in either peripheral blood mononuclear cells or in plasma is most useful. HIV infection is
presumptively excluded with 2 negative virological tests, with one at 2 or more weeks of age and
the second at 1 or more months of age. HIV infection can be definitively excluded with 2
negative virological tests, with one at 1 or more months of age and the second at 4 or more
months of age. Testing of cord blood should be avoided because of potential maternal
contamination.[357,365,366]
Presence or absence of detectable HIV soon after birth may explain when transmission of
HIV from mother to baby occurred. Thus, infants are defined as infected in utero if HIV can be
cultured from peripheral blood or HIV can be detected in lymphocytes within 48 hours of birth.
Intrapartum infection is defined in a neonate with a negative HIV culture or PCR assay for HIV
proviral DNA in peripheral blood in the first week of life, but positive thereafter.[181]

CLINICAL FEATURES.-- On average, about 14 to 25% of children born to HIV-1
infected mothers are perinatally infected in the United States and Europe, while about 13 to 42%
of children of HIV-1 infected mothers acquire HIV perinatally in developing nations.[1039]
However, the rate of HIV infection in the firstborn of twins delivered vaginally (35%) is greater
than the rate in second born (15%), and the 15% rate of HIV infection in the firstborn of twins
delivered by cesarean section is greater than the 8% rate for the second born, suggesting that
intrapartum HIV infection occurs.[1040] A greater HIV viral burden in the mother during late
gestation and/or during the time of delivery, as measured by HIV-1 RNA levels, increases the
risk for HIV transmission to the baby. The risk for HIV-1 transmission is increased with preterm
labor and premature rupture of membranes.[179,181,183] The risk is halved with delivery by
elective cesarean section.[181] For mothers with HIV-2 infection, the rate of perinatal
transmission is only 1 to 2%.[187] Breast feeding by HIV-infected mothers further increases the
risk for transmission of HIV to an infant.[169]
The risk for development of opportunistic infections, encephalopathy, and death in these
infected children is increased in the first 18 months of life when, at the time of birth, the mother
had clinical AIDS, p24 antigenemia, or a CD4 lymphocyte count of <400/µL. Almost half of
children die by 18 months of age if mother had clinical AIDS at birth.[1041]