Background. In clinical trials, maternal tetanus toxoid (TT) vaccination is effective in protecting newborns against tetanus infection, but inadequate placental transfer of tetanus antibodies may contribute to lower-than-expected rates of protection in routine practice. We studied the effect of placental malaria and maternal human immunodeficiency virus (HIV) infection on placental transfer of antibodies to tetanus. Methods. A total of 704 maternal-cord paired serum samples were tested by ELISA for antibodies to tetanus. The HIV status of all women was determined by an immunoglobulin G antibody-capture particle-adherence test, and placental malaria was determined by placental biopsy. Maternal history of TT vaccination was recorded. Results. Tetanus antibody levels were reduced by 52% (95% confidence interval [CI], 30%-67%) in newborns of HIV-infected women and by 48% (95% CI, 26%-62%) in newborns whose mothers had active-chronic or past placental malaria. Thirty-seven mothers (5.3%) and 55 newborns (7.8%) had tetanus antibody levels <0.1 IU/mL (i.e., were seronegative). Mothers' self-reported history of lack of tetanus immunization was the strongest predictor of seronegativity and of tetanus antibody levels in maternal and cord serum. Conclusion. Malarial and HIV infections may hinder efforts to eliminate maternal and neonatal tetanus, making implementation of the current policy for mass vaccination of women of childbearing age an urgent priority.
Bibliographical noteFunding Information:
Received 13 December 2006; accepted 8 February 2007; electronically published 29 June 2007. Potential conflicts of interest: none reported. Financial support: UK Department of International Development; Kenya Medical Research Institute; Wellcome Trust (support to the study and grant 63342 to K.M.). This study is published with the permission of the director of the Kenya Medical Research Institute. Reprints or correspondence: Felicity Cutts, London School of Hygiene and Tropical Medicine, Keppel St., London WC1 7HT, UK (email@example.com).