Abstract
BackgroundSeveral studies have shown a prolonged or increased susceptibility to malaria in the post-partum period. A matched cohort study was conducted to evaluate prospectively the susceptibility to malaria of post-partum women in an area where P.falciparum and P.vivax are prevalent.MethodsIn an area of low seasonal malaria transmission on the Thai-Myanmar border pregnant women attending antenatal clinics were matched to a non-pregnant, non-post-partum control and followed up prospectively until 12 weeks after delivery.ResultsPost-partum women (n = 744) experienced significantly less P.falciparum episodes than controls (hazard ratio (HR) 0.39 (95%CI 0.21–0.72) p = 0.003) but significantly more P.vivax (HR 1.34 (1.05–1.72) p = 0.018). The reduced risk of falciparum malaria was accounted for by reduced exposure, whereas a history of P.vivax infection during pregnancy was a strong risk factor for P.vivax in post-partum women (HR 13.98 (9.13–21.41), p<0.001). After controlling for effect modification by history of P.vivax, post-partum women were not more susceptible to P.vivax than controls (HR: 0.33 (0.21–0.51), p<0.001). Genotyping of pre-and post-partum infections (n⊕ = ⊕10) showed that each post-partum P.falciparum was a newly acquired infection.ConclusionsIn this area of low seasonal malaria transmission post-partum women were less likely to develop falciparum malaria but more likely to develop vivax malaria than controls. This was explained by reduced risk of exposure and increased risk of relapse, respectively. There was no evidence for altered susceptibility to malaria in the post-partum period. The treatment of vivax malaria during and immediately after pregnancy needs to be improved.
Highlights
For nearly a century it has been known that pregnant women are more susceptible to malaria than non-pregnant women of a similar age[1]
All confirmed episodes of malaria are treated according to international guidelines[11,12]: P.falciparum is treated with mefloquine + artesunate in non-pregnant individuals, and with quinine or artesunate + clindamycin in pregnant individuals
Primaquine is not used in the study population, because it is contraindicated during pregnancy and lactation
Summary
For nearly a century it has been known that pregnant women are more susceptible to malaria than non-pregnant women of a similar age[1]. Less is known about susceptibility in the postpartum period. Some studies report prolonged and increased susceptibility to malaria comparable to that in pregnancy[2,3], while others report spontaneous clearance of P.falciparum parasites within 24 hours of delivery[4,5]. P.falciparum genotyping suggested persistence of parasites acquired during pregnancy into the post-partum period[3,7]. Submicroscopic infections and ineffective malaria treatment during pregnancy increase the risk of recrudescence in the post-partum period[6,7]. Several studies have shown a prolonged or increased susceptibility to malaria in the post-partum period. A matched cohort study was conducted to evaluate prospectively the susceptibility to malaria of post-partum women in an area where P.falciparum and P.vivax are prevalent
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