Abstract
During pregnancy a variety of immunological changes occur to accommodate the fetus. It is unknown whether these changes continue to affect humoral immunity postpartum or how quickly they resolve. IgG levels were measured to P. falciparum and P. vivax antigens in 201 postpartum and 201 controls over 12 weeks. Linear mixed-effects models assessed antibody maintenance over time and the effect of microscopically confirmed Plasmodium spp. infection on antibody levels, and whether this was different in postpartum women compared with control women. Postpartum women had reduced Plasmodium spp. antibody levels compared to controls at baseline. Over 12 weeks, mean antibody levels in postpartum women increased to levels observed in control women. Microscopically confirmed P. falciparum and P. vivax infections during follow-up were associated with an increase in species-specific antibodies with similar magnitudes of boosting observed in postpartum and control women. Antibodies specific for pregnancy-associated, VAR2CSA-expressing parasites did not rapidly decline postpartum and did not boost in response to infection in either postpartum or control women. After pregnancy, levels of malaria-specific antibodies were reduced, but recovered to levels seen in control women. There was no evidence of an impaired ability to mount a boosting response in postpartum women.
Highlights
Previous studies have reported increases[21,22], no change[23,24] and decreases[22,23,24,25,26] in P. falciparum antibody levels postpartum compared to pregnancy depending on study site and antigen
To address the paucity of data and investigate whether the postpartum period comprises a period of humoral immunity transitioning to a non-pregnant state, we determined P. falciparum and P. vivax antibody levels at multiple time points in postpartum and control women living at the Thai-Myanmar border
Postpartum women had reduced antibody levels to P. falciparum and P. vivax antigens after delivery when compared with control women, postpartum levels recovered to control levels after 12 weeks
Summary
To assess whether antibodies were boosted in response to infection, species-specific infection during follow-up was included as a time-varying variable with presence of infection (yes or no) at any visit prior to the corresponding antibody level measurement. Seroprevalence and levels of antibodies against P. falciparum and P. vivax antigens were reduced in postpartum compared with control women, with varying degrees of magnitude depending on antigen (Fig. 1). In the absence of an infection, P. falciparum and P. vivax antibody levels appeared relatively stable in postpartum and control women during the 12-week follow-up period (Supplementary Figures 1 and 2).
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