HIV Vertical Transmission Rates Research Articles

HIV Vertical Transmission Rate Determinations Are Subject to Differing Definitions and Therefore Different Rates

The HIV infection status of a cohort of 600 prospectively followed children born to HIV infected mothers was determined using HIV peripheral blood culture tests at 0, 3, and 6 months of age, HIV serology at ≥15 months, and CDC AIDS criteria. We estimated transmission rates using five methods which differed in how HIV indeterminates are handled. These methods were applied at two points in time to illustrate effects of length of follow-up of the cohort on results. In January 1997, 30 months after the last birth, transmission rate estimates ranged from 15.5% (known positives/known positives × known negatives) to 18.1% (known positives × those with one positive culture × deaths/entire cohort minus those lacking negative cultures at age ≥5 months). Estimates ranged from 14.8% to 20.7% using the subcohort of 284 children followed ≥12 months as of May 1993. These results indicate that methods for assigning HIV infection status and for handling HIV indeterminates should be carefully defined when estimating transmission rates.

Prevention of vertical HIV transmission with zidovudine: Projected impact of HIV testing and prenatal care

We sought to estimate the impact of maternal HIV testing and prenatal care on the potential to reduce vertical transmission through zidovudine (AZT) use by HIV-infected mothers. We evaluated the prepartum maternal HIV diagnosis rate, prenatal care, disease stage, and vertical transmission rate (from a two-part mixture model) using New York State Medicaid and vital statistics data for HIV-infected mothers and their singletons in 1985-90. We used published data to estimate the effect of AZT on vertical transmission and expert input to define other parameters for the model. Our HIV-infected (N = 1514) had a vertical transmission rate of 27.0%. HIV was diagnosed prepartum for 39.5% of women in 1990. Transmission would have been 22.2% if AZT had been taken only by the subset of women diagnosed prepartum with HIV and receiving prenatal care by 34 weeks gestation (86.7%). Transmission would have dropped to 11.2% if all women had been diagnosed prepartum with HIV and received adequate prenatal care. The observed deficiencies in prenatal care and maternal HIV diagnosis rates in this Medicaid population-based cohort must be addressed to realize the promise of AZT to reduce vertical transmission.

MATERNAL-FETAL TRANSMISSION OF HIV IN SOUTHEASTERN VIRGINIA: IMPACT OF PERINATAL ZIDOVUDINE (ZDV) USE. • 638

Objectives. To evaluate the rate of vertical transmission of HIV in southeastern Virginia for the past 7.5 years and to determine the impact of ZDV use as recommended by the CDC on the vertical transmission rate since July, 1994. Methods. A retrospective chart review was conducted to identify demographic, diagnostic, and ZDV use information in mother/infant pairs treated at a regional multidisciplinary maternal-child HIV clinic. A case was defined as an infant born to a known HIV infected mother between 1/1/88 and 8/31/95. Study children were stratified by the timing of exposure to ZDV: during pregnancy, during labor and delivery, and/or during the neonatal period. An infant was considered infected if one test detected HIV DNA by PCR after six weeks of age, and uninfected if there was one negative HIV DNA by PCR test after six weeks of age. Results. One hundred twenty-six children met study criteria. 54% were female and 46% were male. 86% were African American, 11% Caucasian, 2% Latino, and 1% American Indian. 18 of 24 (75%) infants born since July, 1994 received prophylactic treatment with ZDV as recommended. 3 of 18 (17%) were infected and 3 (17%) were indeterminant. 19 of 75 (25%) infants born with no perinatal ZDV exposure were infected (p =.13) and 3 (4%) were lost to follow-up. 2 of 20 (10%) infants with ZDV exposure only during pregnancy (p = 12); and 2 of 9 (22%) infants exposed at other times were infected. 15 of 43 (35%) infants were infected when the mothers' CD4 counts were 500 (p =.046).Conclusions. The HIV vertical transmission rate of 25% in our region was similar to the national experience. The vertical transmission rate of 17% despite prophylactic use of ZDV is higher than expected. Further study is needed to determine the impact of prophylactic ZDV on vertical transmission in HIV infected women with symptomatic HIV infection and to address problems with compliance in the treated population.

SENSITIVITY, SPECIFICITY, AND PREDICTIVE VALUE OF PHYSICAL EXAMINATION, CULTURE, AND OTHER LABORATORY STUDIES IN THE DIAGNOSIS DURING EARLY INFANCY OF VERTICALLY ACQUIRED HUMAN IMMUNODEFICIENCY VIRUS INFECTION

Purpose of the Study. To determine the HIV vertical transmission rate in an unselected group of infants born to HIV-infected mothers, and to examine the sensitivity, specificity, and positive and negative predictive values of physical examination and diagnostic laboratory studies (HIV culture, serum quantitative immunoglobulins and HIV-1 p24 antigen) in the diagnosis of HIV infection. Study Population. A group of 142 infants referred solely because they were born to HIV-infected mothers were selected for this study. Methods. Epidemiological and clinical data were obtained retrospectively from the Baylor Pediatric AIDS Clinical Trials Group HIV Infection Registry and medical records. The information recorded included results of physical examination and diagnostic laboratory tests (HIV culture, serum quantitative immunoglobulins, and HIV-1 p24 antigen). HIV cultures were performed according to a consensus protocol developed for the National Institute of Allergy and Infectious Diseases AIDS Clinical Trials Group. Results. Of 142 infants whose HIV infection status was known at the time of the study, 17 (20%) had confirmed infection, and 68 (80%) had seroreverted with no evidence of infection. All HIV-infected infants were at least 3 months old when abnormal physical exam findings became apparent (lymphadenopathy and hepatosplenomegaly), but similar findings were noted in an equal number of HIV-uninfected infants. All infected infants available were HIV culture positive by 6 months of age (16/16). There was no positive cultures reported in the infants who seroreverted (32/32). Elevated immunoglobulins (IgG, IgA, IgM) were present by 6 months of age in a high percentage of infected infants. Nearly one-half of the uninfected infants had elevated immunoglobulin levels during the first 6 months of life, but in 50% of the cases it was IgG alone.