What is the treatment for schistosomiasis (bilharzia)?

Treatment of Bilharzia (Schistosomiasis)

Praziquantel is the drug of choice for treating all forms of schistosomiasis (bilharzia), with specific dosing regimens based on the infecting Schistosoma species. 1

Recommended Treatment Regimens

• For Schistosoma mansoni, S. intercalatum, and S. guineensis infections: Praziquantel 40 mg/kg orally as a single dose 1
• For Schistosoma japonicum and S. mekongi infections: Praziquantel 60 mg/kg orally in two divided doses 1
• For infections diagnosed by serology alone from the Asia-Pacific region: Praziquantel 60 mg/kg orally in two divided doses 1

Treatment Efficacy

• Praziquantel demonstrates high efficacy with egg reduction rates of 91.9% to 99.9% across different Schistosoma species 2
• Cure rates are generally high, ranging from 79% to 99.1% depending on the species and infection intensity 2

Special Clinical Scenarios

Acute Schistosomiasis (Katayama Syndrome)

• Present in travelers 2-8 weeks after exposure to contaminated water 1
• Treatment approach:
  • Corticosteroids (prednisolone 30 mg daily for 5 days) to reduce symptom duration 1
  • Caution: Dexamethasone may reduce praziquantel levels due to increased metabolism 1
  • Praziquantel should be administered after the acute inflammatory phase 1

Neuroschistosomiasis

• For CNS involvement (rare but serious complication):
  • Praziquantel 40 mg/kg twice daily for 5 days 1
  • Combined with dexamethasone 4 mg four times daily, reducing after 7 days, for a total of 2-6 weeks 1
  • In acute neuroschistosomiasis, corticosteroids should be given first, before anthelmintic therapy 1

Monitoring and Follow-up

• Serology may remain positive for many years after successful treatment and cannot be used to assess treatment success 1
• Reinfection rates vary widely (8.1%-63.4%) within 8-28 weeks following treatment, necessitating preventive measures 2

Treatment Challenges

• Reduced susceptibility to praziquantel has been reported in some field isolates of S. mansoni 3
• Treatment failures have been documented in S. haematobium infections despite standard therapy 3
• In areas with potential resistance concerns, consider monitoring stool or urine samples post-treatment to confirm cure 2

Prevention of Reinfection

• Avoid contact with freshwater in endemic areas where snails may be present 4
• Health education and improved sanitation are essential components of comprehensive control 4, 5

Common Pitfalls to Avoid

• Failing to adjust dosage based on Schistosoma species can lead to treatment failure 1
• Using serology alone to assess treatment success is misleading as antibodies persist for years 1
• Administering praziquantel during acute Katayama syndrome without steroids may worsen symptoms 1
• Not considering potential co-infection with strongyloidiasis before starting corticosteroids, which could precipitate hyperinfection syndrome 1