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Old 12-13-2011
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Question HIV diagnosis

Why is that P24 arises early in HIV but it takes some time for Gp 120 and gp41 to rise untill the end of window period.

Also why do we do PCR diagnosis in a neonate,can we not to P24 in that case as well

one of my friends took the exam and he had a q related to the first part of my query.
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zohaib (12-13-2011)

Old 12-13-2011
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Diagnosis of HIV infection in infants is aided by HIV culture or DNA/RNA polymerase chain reaction (PCR); positive results are confirmed by repeating the test. In suspected cases, HIV testing should occur in the newborn period (ie, before the infant is 48 h old), at age 1-2 months, and again at age 3-6 months. Testing at age 14 days may allow for earlier detection of HIV in infants who had negative test results within the first 48 hours of life. By approximately age 1 month, PCR testing has a 96% sensitivity and 99% specificity to identify HIV.

The 2010 Panel on Antiretroviral Therapy and Medical Management of HIV-Infected Children[29] recommendations for diagnosing infants are as follows:

Because of the persistence of the maternal HIV antibody, infants younger than 18 months require virologic assays that directly detect HIV in order to diagnose HIV infection
Preferred virologic assays include HIV DNA PCR and HIV RNA assays
Virologic diagnostic testing is recommended at birth in infants at high risk of HIV infection (eg, infants born to HIV-infected mothers who did not receive prenatal care or prenatal antiretroviral therapy or who had HIV viral loads ≥1,000 copies/mL close to time of delivery)
Further virologic testing in infants with known perinatal HIV exposure is recommended at 14-21 days, at 1–2 months, and at 3–6 months.
An antibody test to document seroreversion to HIV antibody–negative status in uninfected infants is recommended at age 12–18 months
In children 18 months and older, HIV antibody assays can be used for diagnosis

The Panel does not recommend use of the currently approved HIV p24 antigen assay for infant diagnosis in the United States because the sensitivity and specificity of the assay in the first months of life is less than that of other HIV virologic tests.

Within the first 48 hours, 14 days, and 4 weeks of life, 38%, 93%, and 96% of infected children, respectively, have positive HIV DNA PCR results. Any positive HIV DNA PCR finding should be confirmed with follow-up HIV DNA PCR before infection is diagnosed.

HIV infection can be ruled out if one of the following is true:

DNA HIV PCR results are consistently negative in an infant older than 4 months in the absence of breastfeeding.
Two DNA HIV PCR results obtained at least a month apart are negative in an infant older than 6 months.

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