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Open Access Highly Accessed Research article

Effect of praziquantel treatment of Schistosoma mansoni during pregnancy on immune responses to schistosome antigens among the offspring: results of a randomised, placebo-controlled trial

Robert Tweyongyere12*, Patrice A Mawa2, Macklyn Kihembo2, Frances M Jones3, Emily L Webb4, Stephen Cose24, David W Dunne3, Birgitte J Vennervald5 and Alison M Elliott24

Author Affiliations

1 Faculty of Veterinary Medicine, Makerere University, Kampala, Uganda

2 Medical Research Council/Uganda Virus Research Institute-Uganda Research Unit on AIDS, Entebbe, Uganda

3 Department of Pathology University of Cambridge, Cambridge, UK

4 London School of Hygiene and Tropical Medicine, London, UK

5 DBL-Centre for Health Research and Development, Department of Veterinary Disease Biology, University of Copenhagen, Copenhagen, Denmark

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BMC Infectious Diseases 2011, 11:234  doi:10.1186/1471-2334-11-234

Published: 2 September 2011

Abstract

Background

Offspring of women with schistosomiasis may exhibit immune responsiveness to schistosomes due to in utero sensitisation or trans-placental transfer of antibodies. Praziquantel treatment during pregnancy boosts maternal immune responses to schistosome antigens and reduces worm burden. Effects of praziquantel treatment during pregnancy on responses among offspring are unknown.

Methods

In a trial of anthelminthic treatment during pregnancy in Uganda (ISRCTN32849447; http://www.controlled-trials.com/ISRCTN32849447/elliott webcite), offspring of women with Schistosoma mansoni were examined for cytokine and antibody responses to schistosome worm (SWA) and egg (SEA) antigen, in cord blood and at age one year. Relationships to maternal responses and pre-treatment infection intensities were examined, and responses were compared between the offspring of women who did, or did not receive praziquantel treatment during pregnancy.

Results

Of 388 S. mansoni-infected women studied, samples were obtained at age one year from 215 of their infants. Stool examination for S. mansoni eggs was negative for all infants. Cord and infant samples were characterised by very low cytokine production in response to schistosome antigens with the exception of cord IL-10 responses, which were substantial. Cord and infant cytokine responses showed no association with maternal responses. As expected, cord blood levels of immunoglobulin (Ig) G to SWA and SEA were high and correlated with maternal antibodies. However, by age one year IgG levels had waned and were hardly detectable. Praziquantel treatment during pregnancy showed no effect on cytokine responses or antibodies levels to SWA or SEA either in cord blood or at age one year, except for IgG1 to SWA, which was elevated in infants of treated mothers, reflecting maternal levels. There was some evidence that maternal infection intensity was positively associated with cord blood IL-5 and IL-13 responses to SWA, and IL-5 responses to SEA, and that this association was modified by treatment with praziquantel.

Conclusions

Despite strong effects on maternal infection intensity and maternal immune responses, praziquantel treatment of infected women during pregnancy had no effect on anti-schistosome immune responses among offspring by age one year. Whether the treatment will impact upon the offspring's responses on exposure to primary schistosome infection remains to be elucidated.

Trial registration

ISRCTN: ISRCTN32849447