# Investigating genetic profiles of cases of Schistosoma spp. imported into Europe: a cohort from the European Society of Clinical Microbiology and Infectious Diseases Study Group for Clinical Parasitology

## TL;DR

This study analyzed the genetic profiles of Schistosoma infections in European travelers and migrants, finding that mixed infections are common and mostly from West Africa.

## Contribution

The study provides new insights into the genetic diversity and geographic origins of imported Schistosoma infections in Europe.

## Key findings

- Most infections were caused by Schistosoma haematobium and Schistosoma mansoni.
- Mixed Schistosoma genetic profiles were identified in 30% of samples, primarily from West Africa.
- Urinary schistosomiasis cases had a high prevalence of mixed infections involving S. haematobium and Schistosoma bovis.

## Abstract

The potential of schistosomiasis to spread across borders, coupled with the considerable delay by which infected travellers and migrants are diagnosed in Europe, calls for better surveillance of the distribution of this disease. This study explored the geographical origin and genetic profiles of Schistosoma infections imported into Europe and diagnosed in a network of 11 European centres specialized in traveller and migrant health.

Genetic profiles were obtained from DNA extracted from concentrated Schistosoma eggs or Schistosoma-positive samples (faeces, urine, biopsy) collected during routine diagnostic procedures. The species-specific cytochrome oxidase sub-unit 1 (cox1) diagnostic region and the standard complete internal transcribed spacer (ITS) 1 + ITS2 (ITS1 + 2) ribosomal DNA region were amplified and sequenced, together with a partial region of 18S ribosomal DNA in selected cases. Prevalences of the different genetic profiles within the whole patient cohort and by country/geographical area of possible infection were analysed. A phylogenetic analysis was performed using the larger cox1 (~ 956 base pairs) sequences dataset.

A total of 94 samples were available for analysis, 36 from patients with a diagnosis of intestinal schistosomiasis and 58 with urinary schistosomiasis, all acquired in a sub-Saharan African country. Mitochondrial (mt) cox1, nuclear ITS1 + 2 and/or 18S (mt/nuclear) genotypes were successfully obtained from 51/94 (54%) samples; while for 43/94 (46%) samples, only a partial mt genotype was obtained. Infections with Schistosoma haematobium and Schistosoma mansoni were identified in the majority of cases (66/94; 70%), while mixed Schistosoma spp. genetic profiles, which were identified in 30% (28/94) of the samples, were almost exclusively (27/28; 96%) associated with cases of urinary schistosomiasis. Among the urinary infections, almost half (27/58; 47%) could be identified as having a mixed genetic profile. These mostly (26/28; 93%) included genetic traits of S. haematobium and Schistosoma bovis, and all were from patients probably infected in West Africa.

Infections with S. haematobium and S. mansoni represent the majority of cases of schistosomiasis currently being diagnosed in Europe; however, mixed Schistosoma genetic profiles (mostly S. haematobium/S. bovis) were identified in at least 30% of samples. Our results call for a coordinated effort encompassing prompt diagnosis and treatment of Schistosoma infections, together with monitoring of the possible introduction of species of Schistosoma and establishment of their autochthonous transmission under suitable conditions in Europe.

The online version contains supplementary material available at 10.1186/s13071-025-07164-5.