Human Placental Schistosomiasis – a Review of the Literature

Background: Schistosome egg deposition in pregnant women may affect the placenta of infected mothers and cause Placental Schistosomiasis (PS). Histopathological examination of placental tissue is an inadequate detection method due to low sensitivity. So far, there has not been any sys-tematic review on PS. Methods: We conducted a systematic literature search on PubMed and in-cluded relevant secondary literature found in the citations of the primarily included publications. Results: We found a total of 8 publications describing PS with a total of 92 cases, describing egg deposition of dead and/or viable eggs and worms of S. haematobium and S. mansoni in placental tissue. One cross-sectional study investigating the prevalence of PS and its association to adverse birth outcomes, found 22% of placentas to be infested using a maceration technique but only < 1% using histologic examination. Additionally, no direct link to deleterious pregnancy outcomes could be shown. Conclusions: PS is a highly unattended and underdiagnosed condition in en-demic populations, due to a lack of awareness as well as low sensitivity of histopathological examinations. However, PS may play an important role in mediating or reinforcing adverse birth outcomes (ABO) such as fetal growth restriction (FGR) in maternal schistosomiasis, possibly by placental inflammation.