Acute schistosomiasis in travellers: outcomes of a short-course therapy.

Background: Therapy of acute schistosomiasis in travellers currently relies on poorly consistent combinations of corticosteroids and praziquantel. In a cluster of travellers recently infected with Schistosoma mattheei × Schistosoma haematobium hybrids during a trip to South Africa in 2017, we evaluated the safety and efficacy of short methylprednisolone cycles to suppress early symptoms and of a single-day praziquantel/methylprednisolone administration at well-defined time lapses.

Methods: Symptomatic patients seen during the early phase, 4 to 5 weeks (week 4-5) after infection, were given oral methylprednisolone 0.5 mg/kg once daily in one or more cycles of three consecutive days until symptoms abated. Patients were seen again at week 7-8 to be given praziquantel 40 mg/kg in two divided doses 2 hours apart, followed by a single dose of oral methylprednisolone 0.5 mg/kg 2 hours later to prevent symptom exacerbation. All patients were reevaluated for symptoms and infection at week 12-14, using serum circulating anodic antigen (CAA) as a marker of active infection.

Results: A total of 34 infected individuals were longitudinally followed up. Of these, 21 patients with symptoms at presentation (week 4-5) were given methylprednisolone. Symptoms abated during the first three-day cycle in 15/21 (71%), during the second cycle in another 4/21 (19%), and during the third cycle in the remaining 2/21 (10%). All 34 participants were treated with the praziquantel/steroid combination at week 7-8; 9 (26%) had mild symptoms of short duration. Only 4 (12%) developed fever and needed 1 or 2 additional days of steroids. At week 12-14, serum CAA remained detectable in only one of the 34 participants.

Conclusion: In most patients, a single three-day course of methylprednisolone was sufficient to suppress symptoms of acute schistosomiasis. Only few patients experienced short lived symptom exacerbation after taking a single-day praziquantel and methylprednisolone combination at 7-8 weeks following exposure. Infection was cleared in almost all cases 4-6 weeks later.