Acute schistosomiasis in travelers: outcomes of a short-course therapy

BACKGROUND: Therapy of acute schistosomiasis in travelers currently relies on poorly consistent combinations of corticosteroids and praziquantel. In a cluster of travelers recently infected with Schistosoma mattheei X S. 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 (w4-5) after infection were given oral methylprednisolone 0.5mg/kg once daily in one or more cycles of three consecutive days until symptoms abated. Patients were seen again at w7-8 to be given praziquantel 40mg/kg in two divided doses 2 hours apart, followed by a single dose of oral methylprednisolone 0.5mg/kg two hours later to prevent symptom exacerbation. All patients were reevaluated for symptoms and infection at w12-14, 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 (w4-5) 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 w7-8; 9 (26%) had mild symptoms of short duration. Only 4 (12%) developed fever, and needed 1 or 2 additional days of steroids. At w12-14, 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.