Schistosomiasis is a neglected tropical disease despite of being a major public health problem affecting nearly 240 million people in the world. Due to the migratory flow from endemic countries to Western countries, an increasing number of cases is being diagnosed in non-endemic areas, generally in migrants or people visiting these areas. Serology is the recommended method for screening and diagnosis of schistosomiasis in migrants from endemic regions. However, serological techniques have a highly variable sensitivity. The aim of this study was to evaluate retrospectively the sensitivity of three different serological tests used in real clinical practice for the screening and diagnosis of imported schistosomiasis in sub-Saharan migrant patients, using the detection of schistosome eggs in urine, faeces or tissues as the gold standard. We evaluated three different serological techniques in 405 sub-Saharan patients with confirmed schistosomiasis treated between 2004 and 2022: an enzyme-linked immunosorbent assay (ELISA), an indirect haemagglutination assay (IHA) and an immunochromatographic test (ICT). The overall sensitivity values obtained with the different techniques were: 44.4% for IHA, 71.2% for ELISA and 94.7% for ICT, respectively. According to species, ICT showed the highest sensitivity (S. haematobium: 94%, S. mansoni: 93.3%; and S. intercalatum/guineensis: 100%). In conclusion, our study shows that Schistosoma ICT has the best performance in real clinical practice, when compared to ELISA and IHA, in both S. mansoni and S. haematobium infections.

Mitochondrial cox 1 and nuclear ribosomal ITSs are commonly combined to distinguish Schistosoma species and identify hybrids in endemic countries but very rarely applied to patients diagnosed in Europe despite the increasing arrival of migrants in southwestern Europe. To assess whether those migrants are carriers of pure or hybrid schistosomes, a complete genetic characterization of Schistosoma entering Spain is performed. A total of 759 eggs (from urine + stools) from 58 patients from 8 African countries were individually processed to describe their mito‐nuclear signature by cox 1 rapid diagnostic multiplex one‐step polymerase chain reaction (RD‐PCR) and ITS‐2/18S sequencing and haplotype identification by means of the complete ITS1‐5.8S‐ITS2 rDNA and cox 1 sequencing. Combined nuclear and mitochondrial DNA markers in sub‐Saharan migrants residing in Spain are described for the first time. Twenty‐two (40.74%) patients were simultaneously carrying pure and hybrid eggs in their urine. S chistosoma haematobium × S. bovis (68.18%) and S. haematobium × S. curassoni (31.82%) hybrid combinations were the most frequent. Six (one pure and five hybrid) and two (pure) mito‐nuclear signatures, in urine and stools, respectively, and 12 nuclear and 61 mitochondrial imported haplotypes were found. This study highlights the genetic complexity of pure and hybrid schistosomes that enter Spain, and consequently Europe, and contributes to the following: correlate the geographical origin of patients with pure and/or hybrid genetic types; detect the presence of hybrids “at distance” (hybrids in migrants from Guinea‐Bissau and Mauritania are first time detected); correlate molecular haplotypes with pathologies, clinical pictures, and treatment responses; and, importantly, warn about possible sources of autochthonous transmission.

Migratory flows and international travel are triggering an increase in imported cases of schistosomiasis in non-endemic countries. The present study aims to evaluate the effectiveness of the LAMP technique on patients’ urine samples for the diagnosis of imported schistosomiasis in a non-endemic area in comparison to a commercial immunochromatographic test and microscopic examination of feces and urine. A prospective observational study was conducted in sub-Saharan migrants attending the Tropical Medicine Unit, Almería, Spain. For schistosomiasis diagnosis, serum samples were tested using an immunochromatographic test (Schistosoma ICT IgG-IgM). Stool and urine samples were examined by microcopy. Urine samples were evaluated by combining three LAMP assays for the specific detection of Schistosoma mansoni, S. haematobium, and for the genus Schistosoma. To evaluate the diagnostic accuracy, a latent class analysis (LCA) was performed. In total, 115 patients were included (92.2% male; median age: 28.3 years). Of these, 21 patients (18.3%) were diagnosed with schistosomiasis confirmed by microscopy, with S. haematobium being the most frequent species identified (18/115; 15.7%). The Schistosoma ICT IgG-IgM test result was 100% positive and Schistosoma-LAMP was 61.9% positive, reaching as high as 72.2% for S. haematobium. The sensitivity and specificity estimated by LCA, respectively, were: 92% and 76% for Schistosoma ICT IgG-IgM, 68% and 44% for Schistosoma-LAMP, and 46% and 97% for microscopy. In conclusion, the Schistosoma-LAMP technique presented a higher sensitivity than microscopy for the diagnosis of imported urinary schistosomiasis, which could improve the diagnosis of active infection, both in referral centers and in centers with limited experience or scarce resources and infrastructure.

Schistosome eggs play a key role in schistosomiasis diagnosis and research. The aim of this work is to morphogenetically study the eggs of Schistosoma haematobium found in sub-Saharan migrants present in Spain, analyzing their morphometric variation in relation to the geographical origin of the parasite (Mali, Mauritania and Senegal). Only eggs considered “pure” S. haematobium by genetic characterization (rDNA ITS-2 and mtDNA cox1) have been used. A total of 162 eggs obtained from 20 migrants from Mali, Mauritania and Senegal were included in the study. Analyses were made by the Computer Image Analysis System (CIAS). Following a previously standardized methodology, seventeen measurements were carried out on each egg. The morphometric analysis of the three morphotypes detected (round, elongated and spindle) and the biometric variations in relation to the country of origin of the parasite on the egg phenotype were carried out by canonical variate analysis. Mahalanobis distances, when all egg measurements were analyzed, showed differences between: (i) Mali-Mauritania, Mali-Senegal and Mauritania-Senegal in the round morphotype; (ii) Mali-Mauritania and Mauritania-Senegal in the elongated morphotype; and (iii) Mauritania-Senegal in the spindle morphotype. Mahalanobis distances, when spine variables were analyzed, showed differences between Mali-Senegal in the round morphotype. In conclusion, this is the first phenotypic study performed on individually genotyped “pure” S. haematobium eggs, allowing the assessment of the intraspecific morphological variations associated with the geographical origin of the schistosome eggs.

In Europe, imported schistosomiasis affects a diverse range of patients, including migrants, travellers, visiting friends and relatives, and expatriates who have lived in endemic areas. The variety of regions linked to these patients’ origins or destinations increases the likelihood of infections from different Schistosoma species and hybrids. This work aims to address the multidisciplinary challenges posed by ‘pure’ and hybrid Schistosoma species in southwestern Europe. It explores (i) the role of molecular analysis in identifying species and hybrids, (ii) the importance of morphogenetic studies of Schistosoma eggs, (iii) the potential risk of hybrid Schistosoma infections emerging in Europe and (iv) the clinical management, diagnostis and treatment of schistosomiasis in non-endemic European countries. The study includes examples of ‘pure’ and hybrid species detected in a tropical medicine unit in Almería, Spain. In this context, the complexity of managing not only the clinical aspects, diagnosis and treatment of this disease, but also the need and readiness to quantify the risks and prevent future outbreaks of schistosomiasis in Europe are evident. Schistosoma hybrids potentially able to adapt to new European habitats are a challenge, which highlights the need for appropriate surveillance and preventive measures to avoid the introduction of schistosomiasis into Europe. This article is part of the Science+ meeting issue ‘Parasite evolution and impact in action: exploring the importance and control of hybrid schistosomes’.

Migratory flows and international travel are triggering an increase in imported cases of schistosomiasis in non-endemic countries, with serology being the recommended method for screening migrants. The present study aims to evaluate, for the first time, the LAMP technique on patients’ urine samples for the diagnosis of imported schistosomiasis in a non-endemic area in comparison to a commercial immunochromatographic test and microscopic examination of feces and urine. A prospective observational study was conducted in sub-Saharan migrants attending at the Tropical Medicine Unit, Almería, Spain. For schistosomiasis diagnosis, serum samples were tested using an immunochromatographic test (Schistosoma ICT IgG-IgM). Stool and urine samples were examined by microcopy. Urine samples were evaluated by combining three LAMP assays for the specific detection of Schistosoma mansoni and S. haematobium, and an assay for the genus Schistosoma. To evaluate the diagnostic accuracy of Schistosoma-LAMP in comparison to microscopy and Schistosoma ICT IgG-IgM test, a Latent Class Analysis (LCA) was performed. A total of 115 patients were included; 21 patients (18.3%) were diagnosed with schistosomiasis confirmed by microscopy, with S. haematobium being the most frequent species identified (18/115; 15.7%). The Schistosoma ICT IgG-IgM test resulted 100% positive and Schistosoma-LAMP was 61.9% positive, reaching as high as 72.2% for S. haematobium. The sensitivity and specificity estimated by LCA, respectively, were: 92% and 76% for Schistosoma ICT IgG-IgM, 68% and 44% for Schistosoma-LAMP and, 46% and 97% for microscopy. The Schistosoma-LAMP technique presented a higher sensitivity than microscopy for the diagnosis of imported urinary schistosomiasis, which could improve the diagnosis both in referral centers and in centers with limited experience or scarce resources and infrastructure.