AEGiS-13IAC: Breastmilk infectivity of HIV-1 infected mothers.

13th International AIDS Conference

Durban, South Africa - July 9-July 14, 2000

Breastmilk infectivity of HIV-1 infected mothers.

Int Conf AIDS 2000 Jul 9-14; 13:(abstract no. WeOrC492)

Richardson B, John G, Hughes J, Nduati R, Mbori Ngacha D, Kreiss J
B. Richardson, University of Washington, University of Washington, PO Box 359909, Seattle, WA 98199, United States, Tel.: +1 206 731 2425, Fax: +1 206 731 2427, E-mail: barbrar@u.washington.edu

INTRODUCTION: The probability of male to female HIV-1 infection per sex act is estimated to be between .0005 to .001. We evaluated the probability of breastmilk transmission of HIV-1 per day of breastfeeding and per liter of breastmilk ingested.

METHODS: In a study of mother-to-child transmission of HIV-1 in Nairobi, mother/infant pairs were followed for 2 years postpartum. Breastfeeding information was collected monthly during the first year, and 3 monthly the second year. HIV-1 DNA PCR assays were conducted on infant blood at 6 weeks, 14 weeks, and then 3-monthly until 24 months. Using a mixture model, breastmilk infectivity at > = 4 months and >4 months were estimated per day of breastfeeding and per liter of breastmilk ingested. Overall breastmilk infectivity was compared for mothers with high and low plasma HIV-1 RNA levels.

RESULTS: We included 362 infants with > = 1 HIV-1 test and breastfeeding information in the analyses. Median duration of breastfeeding was 17 months. Probability of breastmilk transmission of HIV-1 per liter ingested was .00073 for infants > = 4 months, and .00076 for infants >4 months. Probability of breastmilk transmission of HIV-1 per day of breastfeeding was .00042 for infants >4 months, and .00026 for infants >4 months. Women with plasma HIV-1 RNA viral loads > = median in the cohort had a higher probability of breastmilk transmission per liter ingested by the infant than women > median (.00096 vs .00044).

CONCLUSIONS: HIV-1 infectivity appears to be constant per liter ingested over time. HIV-1 infectivity per day of breastfeeding was 1.6 times higher for infants > = 4 months than for those >4 months. These results indicate that volume of milk ingested and length of exposure are both important factors in breastmilk transmission of HIV-1. High maternal plasma HIV-1 RNA levels were associated with higher breastmilk infectivity.

Keywords: AEGIS, HIV-1, Mothers, Breast Feeding, Viral Load, Pregnancy Complications, Infectious, Infant Food, Infection, Puerperal Infection, Infant Mortality, Probability, Infant, Human, Female, Child, Male, transmission
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