Serology- and Blood-PCR-Based Screening for Schistosomiasis in Pregnant Women in Madagascar—A Cross-Sectional Study and Test Comparison Approach

Abstract

This work was conducted as a cross sectional study to define the disease burden of schistosomiasis in pregnant Madagascan women and to evaluate serological and molecular diagnostic assays. A total of 1154 residual EDTA blood samples from pregnant Madagascan women were assessed. The nucleic acid extractions were subjected to in-house real-time PCRs specifically targeting S. mansoni complex, S. haematobium complex, and African Schistosoma spp. on genus level, while the EDTA plasma samples were analyzed using Schistosoma-specific IgG and IgM commercial ELISA and immunofluorescence assays. The analyses indicated an overall prevalence of schistosomiasis in Madagascan pregnant women of 40.4%, with only minor regional differences and differences between serology- and blood PCR-based surveillance. The S. mansoni specific real-time PCR showed superior sensitivity of 74% (specificity 80%) compared with the genus-specific real-time PCR (sensitivity 13%, specificity 100%) in blood. The laborious immunofluorescence (sensitivity IgM 49%, IgG 87%, specificity IgM 85%, IgG 96%) scored only slightly better than the automatable ELISA (sensitivity IgM 38%, IgG 88%, specificity IgM 78%, IgG 91%). Infections with S. mansoni were detected only. The high prevalence of schistosomiasis recorded here among pregnant women in Madagascar calls for actions in order to reduce the disease burden.

Predictive Risk Mapping of Schistosomiasis in Madagascar Using Ecological Niche Modeling and Precision Mapping

“…Geographic records of both Schistosoma haematobium (n = 80) and Schistosoma mansoni (n = 120) were collected from the Global Atlas of Helminth Infections (GAHI) (http://www.thiswormyworld.org/) (access date: 2 November 2021) [33] and the World Health Organization (WHO) [34]. Supplementing these data were literature on confirmed human (n = 12) and animal (n = 1) cases [35][36][37][38][39][40][41][42][43][44]…”

Low Sensitivity of Real Time PCRs Targeting Retrotransposon Sequences for the Detection of Schistosoma japonicum Complex DNA in Human Serum

“…Hybridization-probe-based real-time PCR targeting multi-copy sequences is a well-established approach for the diagnosis of infections with parasites of the S. haematobium complex and the S. mansoni complex in human serum [ 2 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. To facilitate the diagnosis of schistosomiasis caused by parasites of the Asian S. japonicum complex, calls for action to develop similar diagnostic options were published earlier [ 34 ].…”

“…The reasons for the much lower diagnostic sensitivity of SjR2 -PCR and SjCHGCS19 -PCR for the detection of S. japonicum complex PCR in human serum compared to PCRs for other highly repetitive multi-copy targets like S. mansoni complex-specific Sm1-7 -PCR or S. haematobium complex-specific Dra1 -PCR [ 2 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ] remain speculative. High genetic intra-species variability of the retrotransposons and varying numbers of repeats within individual worms as described elsewhere [ 18 , 19 ] might make SjR2 and SjCHGCS19 sequences less suitable as real-time PCR targets, at least for the diagnosis from human serum.…”

“…For the African Schistosoma species, highly sensitive real-time PCRs targeting the multi-copy sequences Sm1-7 for S. mansoni complex as well as Dra1 for S. haematobium complex in human serum have been developed [ 2 , 7 , 8 , 9 , 10 ] and well evaluated using sera from travel returnees [ 11 , 12 ] and individuals in endemic areas [ 13 , 14 ]. These assays provide highly sensitive tools for screening and facilitate the identification of both species complexes in parallel in human serum samples as a one-tube multiplex approach [ 12 , 14 ]. Currently, its potential usefulness for schistosomiasis surveillance and control activities is controversially discussed [ 13 , 15 , 16 ].…”

“…Currently, its potential usefulness for schistosomiasis surveillance and control activities is controversially discussed [ 13 , 15 , 16 ]. In contrast, its application for the diagnosis of early infections prior to seroconversion and prior to the excretion of eggs, as well as for the discrimination of active infections from old serological responses to infections that have been successfully cured long ago, is considered as well established [ 12 , 13 , 14 , 15 , 16 ].…”