BackgroundEarlier studies found characteristic haematological changes in African patients with active schistosomiasis. If consistently present, full blood counts (FBC) may be helpful to diagnose schistosomiasis also in migrants and returning travellers.MethodsA retrospective patient record review was conducted on data from seven European travel clinics, comparing FBC ofSchistosomaegg-positive travellers and migrants to reference values. Sub-analyses were performed for children, returned travellers, migrants and differentSchistosomaspecies.ResultsData analysis included 382 subjects (median age 21.0 years [range 2–73]). In returned travellers, decreases in means of haemoglobin particularly in females (β = −0.82 g/dL,p= 0.005), MCV (β = −1.6 fL,p= 0.009), basophils, neutrophils, lymphocytes and monocytes (β = −0.07,p< 0.001; −0.57,p= 0.012; −0.57,p< 0.001 and −0.13 103/μL,p< 0.001, respectively) were observed. As expected, eosinophils were increased (β = +0.45 103/μL, p < 0.001). In migrants, a similar FBC profile was observed, yet thrombocytes and leukocytes were significantly lower in migrants (β = −48 103/μLp< 0.001 and β = −2.35 103/μL,p< 0.001, respectively).ConclusionsActive egg-producingSchistosomainfections are associated with haematological alterations in returned travellers and migrants. However, these differences are discrete and seem to vary among disease stage andSchistosomaspecies. Therefore, the FBC is unsuitable as a surrogate diagnostic parameter to detect schistosomiasis.