Prenatal exposure to Plasmodium falciparum increases frequency and shortens time from birth to first clinical malaria episodes during the first two years of life: Prospective birth cohort study
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Date
2016
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Malaria journal
Abstract
Background: Prenatal exposure to Plasmodium falciparum affects development of protective immunity and sus-
ceptibility to subsequent natural challenges with similar parasite antigens. However, the nature of these effects has
not been fully elucidated. The aim of this study was to determine the effect of prenatal exposure to P. falciparum on
susceptibility to natural malaria infection, with a focus on median time from birth to first clinical malaria episode and
frequency of clinical malaria episodes in the first 2 years of life.
Methods: A prospective birth cohort study was conducted in Rufiji district in Tanzania, between January 2013
and December 2015. Infants born to mothers with P. falciparum in the placenta at time of delivery were defined as
exposed, and infants born to mothers without P. falciparum parasites in placenta were defined as unexposed. Placen-
tal infection was established by histological techniques. Out of 206 infants recruited, 41 were in utero exposed to P.
falciparum and 165 infants were unexposed. All infants were monitored for onset of clinical malaria episodes in the
first 2 years of life. The outcome measure was time from birth to first clinical malaria episode, defined by fever (≥37 °C)
and microscopically determined parasitaemia. Median time to first clinical malaria episode between exposed and
unexposed infants was assessed using Kaplan–Meier survival analysis and comparison was done by log rank. Associa-
tion of clinical malaria episodes with prenatal exposure to P. falciparum was assessed by multivariate binary logistic
regression. Comparative analysis of mean number of clinical malaria episodes between exposed and unexposed
infants was done using independent sample t test.
Results: The effect of prenatal exposure to P. falciparum infection on clinical malaria episodes was statistically signifi-
cant (Odds Ratio of 4.79, 95 % CI 2.21–10.38, p < 0.01) when compared to other confounding factors. Median time
from birth to first clinical malaria episode for exposed and unexposed infants was 32 weeks (95 % CI 30.88–33.12)
and 37 weeks (95 % CI 35.25–38.75), respectively, and the difference was statistically significant (p = 0.003). The mean
number of clinical malaria episodes in exposed and unexposed infants was 0.51 and 0.30 episodes/infant, respec-
tively, and the difference was statistically significant (p = 0.038).
Conclusions: Prenatal exposure to P. falciparum shortens time from birth to first clinical malaria episode and
increases frequency of clinical malaria episodes in the first 2 years of life.
Description
Keywords
Prenatal exposure, Plasmodium falciparum, Clinical malaria episode
Citation
Sylvester, B., Gasarasi, D.B., Aboud, S., Tarimo, D., Massawe, S., Mpembeni, R. and Swedberg, G., 2016. Prenatal exposure to Plasmodium falciparum increases frequency and shortens time from birth to first clinical malaria episodes during the first two years of life: prospective birth cohort study. Malaria journal, 15(1), pp.1-8.