PERTUSSIS IN INFANTS: CHARACTERIZATION OF RISK AND MATERNAL IMMUNOLOGICAL PROTECTION
Monday, 18 August 2014
Exhibit hall (Dena'ina Center)
Michelle J Mergler, MPH
,
Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
Janet A Englund, MD
,
Seattle Children's Hospital/University of Washington, Seattle, WA
James M Tielsch, PhD
,
George Washington University School of Public Health and Health Services, Washington, DC
Jane Kuypers, PhD
,
University of Washington, Seattle, WA
Michael Rock, PhD
,
Vanderbilt University Medical Center, Nashville, TN
Kathryn M Edwards, MD
,
Vanderbilt University, Nashville, TN
Mark C Steinhoff, MD
,
Cincinnati Children's, Cincinnati, OH
Subarna K Khatry, MD
,
Nepal Nutrition Intervention Project - Sarlahi, Kathmandu, Nepal
Steven C LeClerq, MPH
,
Johns Hopkins Bloomberg School of Public Health, Kathmandu, Nepal
Joanne Katz, PhD
,
Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
INTRODUCTION: Pertussis is estimated to contribute to 2% of childhood deaths worldwide. Young infants are at highest risk for serious sequelae of pertussis disease which has recently reappeared in high income countries with high rates of pediatric DTaP vaccination coverage. Vaccination of infants with pertussis vaccine is often delayed in low income countries, and there are few pertussis incidence estimates for infants in such setting where whole cell pertussis vaccine is routinely utilized. Maternal vaccination with Tdap in pregnancy is now recommended in the US/UK, but this vaccine is not available in low income countries. This study estimated population-based incidence of lab proven pertussis in infants < 6 months of age and maternal pertussis antibody transfer to the infants at delivery in rural southern Nepal.
METHODS: Infants were visited weekly from birth through six months to assess respiratory illness in the prior week. If any respiratory symptom was reported, a mid-nasal swab was collected and tested with a multi-target pertussis PCR assay (n=3321). 44 paired maternal and cord blood specimens were collected and tested for antibodies to pertussis toxin using an ELISA.
RESULTS: In a cohort of 3,373 infants, the incidence of PCR-confirmed Bordetella pertussis and Bordetella parapertussis was 5.4/1000 infant years [95% CI, 2.2 -11.2] and 3.1/1000 infant years [95% CI, 0.8 - 7.9], respectively. Mean age of pertussis onset was 72 days (SD:32) and mean birth weight was 2,490 (SD: 428) grams. There was active transfer of pertussis toxoid (PT) antibody from mothers (GMT 9.75) to infants (GMT 11.25) at birth, with an overall infant/mother GMT ratio of 1.15 [95% CI, 1.04-1.28]. However, only 40% of women had detectable pertussis toxoid antibody at delivery. The correlation of specific infant/mother antibody titers was 0.96. Females and infants with longer gestation had more antibody transfer. 40% of infants had not received any DTP vaccine by 6 months of age.
CONCLUSIONS: There was a low risk of symptomatic pertussis disease among young infants in rural Nepal. When present, maternal pertussis antibodies were actively transferred to infants. Although infant vaccine coverage was delayed, Nepal's immunization program appears to controll pertussis in young infants.
