Clinical and epidemiological features of schistosomiasis among sub-Saharan African migrants in Barcelona, Spain: a retrospective observational study

Schistosomiasis is a neglected tropical disease, affecting 253 million people worldwide. This study aimed to describe the clinical and epidemiological characteristics of schistosomiasis in sub-Saharan African migrants evaluated through a general screening program for imported infectious diseases at a specialized international health unit in Barcelona, Spain. We performed a retrospective observational study (2014-2023) including confirmed (defined by egg detection in stool or urine) and probable cases (identified by positive serology against Schistosoma). Data on epidemiology, clinical presentation, diagnosis, treatment, and follow-up were collected. Among 3214 screened migrants, 855 (26.6%) were diagnosed with schistosomiasis. Most were male (87%) with a median age of 21.9 years, mainly originating from Mali, Gambia, and Senegal. Only 2.2% reported symptoms, while anemia and eosinophilia were observed in 9.7% and 29.7% of cases, respectively. Parasitological confirmation was achieved in 24.9%, with the remainder diagnosed by serology alone. Abdominal ultrasound was performed in 122 patients, revealing abnormalities in 20.4%. Multivariate analysis showed that confirmed cases tended to be younger (22.4 years vs 25.8 years) and had higher frequencies of women (17.8% vs 11.3%), symptoms (5.6% vs 1.1%), eosinophilia (49.4% vs 22.5%), and ultrasound abnormalities (22.7% vs 17.8%) than probable cases. Praziquantel treatment was administered to 775 patients (90.6%). Follow-up information was available for 218 individuals (28.1%); among those, eggs persisted in 7.4% (9/122), and 84% (74/88) maintained positive serology. Schistosomiasis prevalence in this migrant population was high and mostly asymptomatic, with limited laboratory abnormalities but notable radiological findings, particularly in confirmed cases. Serology was useful diagnostically but had limited value in follow-up. Systematic screening of at-risk populations remains crucial for early detection and treatment.