Schistosomiasis presenting in travellers: a 15 year observational study at the Hospital for Tropical Diseases, London

Background: Schistosomiasis in returning travellers is one of the most common imported tropical infections with potentially serious complications, which are preventable if diagnosed early. Methods: A review was undertaken of consecutive cases of schistosomiasis presenting at the Hospital for Tropical Diseases, London, UK from 1997 to 2012. Results: All 1020 schistosomiasis cases were from Africa and Schistosoma haematobium was the predominant species in those with microscopy confirmed schistosomiasis (74.2%, 204/252). The number of cases of imported schistosomiasis is decreasing steadily as a proportion of travellers seen. The majority of cases were in travellers originating from non-endemic settings (81.8%, 707/864). The most common symptom was of genitourinary complaints (22.6%, 230/1020), predominantly haematuria (17.8%, 181/1020); 36.1% (368) of cases were asymptomatic. Overall 42% had eosinophilia, and 62% of ova positive S. haematobium cases had haematuria on urine dip. Thus, no single screening tool was sufficient to identify or rule out schistosomiasis when used alone. Serology testing was a more sensitive tool in travellers than in other patients (p=0.007). Conclusions: The prevalence of schistosomiasis in presenting travellers is decreasing. The predominant presenting species has shifted from S. mansoni to S. haematobium. No single test can reliably diagnose schistosomiasis, with eosinophilia and urine dip having low sensitivity. Clinicians need to continue to undertake a wide spectrum of diagnostic tests to ensure cases of schistosomiasis are not missed.