Can changes in malaria transmission intensity explain prolonged protection and contribute to high protective efficacy of intermittent preventive treatment for malaria in infants?

Roly D. Gosling, Azra C. Ghani, Jacqueline L. Deen, Lorenz Von Seidlein, Brian M. Greenwood, Daniel Chandramohan

    Research output: Contribution to journalComment/debate

    Abstract

    Background:  Intermittent preventive  (or presumptive) treatment of infants (IPTi), the administration of a curative anti-malarial dose to infants whether or not they are known to be infected, is being considered as a new strategy for malaria control. Five of the six trials using sulphadoxine-pyrimethamine (SP) for IPTi showed protective efficacies (PEs) against clinical malaria ranging from 20.1 – 33.3% whilst one, the Ifakara study, showed a protective efficacy of 58.6%.

    Materials and methods:  The possible mechanisms that could explain the differences in the reported PE of IPTi were examined by comparing output from a mathematical model to data from the six published IPTi trials.

    Results:  Under stable transmission, the PE of IPTi predicted by the model was comparable with the observed PEs in all but the Ifakara study (ratio of the mean predicted PE to that observed was1.02, range 0.39 – 1.59). When a reduction in the incidence of infection during the study was included in the model, the predicted PE of IPTi increased and extended into the second year of life, as observed in the Ifakara study.

    Conclusion:  A decrease in malaria transmission during the study period may explain part of the difference in observed PEs of IP Ti between sites and the extended period of protection into the second year of life observed in the Ifakara study. This finding of continued benefit of interventions in settings of decreasing transmission may explain why rebound of clinical malaria was absent in the large scale trials of insecticide-treated bed nets.
    Original languageEnglish
    Pages (from-to)-
    Number of pages13
    JournalMalaria Journal
    Volume7
    Issue number1 - Article No. 54
    DOIs
    Publication statusPublished - 2008

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