Reducing pediatric HIV infection: estimating mother-to-child transmission rates in a program setting in Zambia.
BACKGROUND
Vertical transmission of HIV remains the main source of pediatric HIV infection in Africa with transmission rates as high as 25%-45% without intervention. Even though effective interventions to reduce vertical transmission of HIV are now available and remarkable progress has been made in scaling up prevention of mother-to-child transmission (PMTCT) services, the effectiveness of PMTCT interventions is unknown in Zambia. In this study, we estimate HIV vertical transmission rates at different age bands among perinatally exposed children.


METHODS
The study analyzed program data of DNA polymerase chain reaction results and selected client information on dried blood spot samples from perinatally exposed children aged 0-12 months sent to the polymerase chain reaction laboratory from 5 provinces between September 2007 and January 2009.


RESULTS
Samples of 8237 babies between 0 and 12 months were analyzed, with 84% of the mothers having ever breastfed their children. The observed transmission rate was 6.5% (5.1%, 7.8%) among infants aged 0-6 weeks when both mother and infant received interventions compared with 20.9% (12.3%, 29.5%) where no intervention was given to either mother or baby. Observed HIV transmission with single-dose nevirapine (sdNVP) was 8.5% (5.9%, 11.0%) among infants aged 0-6 weeks, whereas zidovudine with sdNVP (zidovudine + NVP) and highly active antiretroviral therapy were associated with observed transmission rates of 6.8% (4.5%, 9.1%) and 5.0% (3.0%, 7.0%), respectively; whereas these estimates were not significantly different from one another, they were all significantly lower than no intervention for which the estimated rate was 20.9%. Regardless of the intervention, the observed transmission rates were higher among infants aged 6-12 months.


CONCLUSIONS
PMTCT interventions, including sdNVP, are working in program settings. However, postnatal transmission especially after 6 months through suboptimal feeding practises remains an important challenge to further reduce pediatric HIV.
Torpey
Kwasi
K
Technical Support Department, Family Health International/Zambia Prevention Care and Treatment Partnership, Lusaka, Zambia. ktorpey@fhi.org
Kasonde
Prisca
P
Kabaso
Mushota
M
Weaver
Mark A
MA
Bryan
Gail
G
Mukonka
Victor
V
Bweupe
Maximillian
M
Zimba
Chilunje
C
Mwale
Felicitas
F
Colebunders
Robert
R
D023241:Antiretroviral Therapy, Highly Active; D001942:Breast Feeding; D002648:Child; D004279:DNA, Viral / Q000235:genetics; D004359:Drug Therapy, Combination; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D015497:HIV-1 / Q000235:genetics; D006801:Humans; D007223:Infant; D041943:Infant Formula; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control*; D008297:Male; D009034:Mother-Child Relations; D019829:Nevirapine / Q000627:therapeutic use; D016017:Odds Ratio; D016133:Polymerase Chain Reaction; D012044:Regression Analysis; D015024:Zambia / Q000453:epidemiology; D015215:Zidovudine / Q000627:therapeutic use
D004279:DNA, Viral; D015215:Zidovudine; D019829:Nevirapine