Treatment of Schistosomiasis
Praziquantel is the recommended first-line treatment for all Schistosoma species infections, with dosing based on the specific species: 40 mg/kg as a single dose for S. mansoni, S. intercalatum, and S. guineensis, and 60 mg/kg in two divided doses for S. japonicum and S. mekongi. 1, 2
Treatment Regimens by Species
S. mansoni, S. intercalatum, and S. guineensis
- Praziquantel 40 mg/kg as a single oral dose 1, 2
- For Katayama syndrome (acute schistosomiasis): Consider adding corticosteroids (prednisolone 30 mg daily for 5 days) to reduce symptom duration 2
S. japonicum and S. mekongi
- Praziquantel 60 mg/kg in two divided doses 1, 2
- Higher dose required due to increased egg production and potentially greater pathogenicity
Timing Considerations
- Praziquantel should be repeated at 6-8 weeks after initial treatment as eggs and immature schistosomules are relatively resistant to the first treatment 2
- This two-treatment approach ensures elimination of parasites that may have been in immature stages during initial treatment
Special Clinical Scenarios
Neurocysticercosis
- For parenchymal disease with 1-2 cysts: Albendazole plus steroids 2
- For parenchymal disease with >2 cysts: Combination of albendazole, praziquantel, and steroids 2
- For co-existing intestinal taeniasis: Niclosamide 2g 2
Katayama Syndrome (Acute Schistosomiasis)
- Praziquantel plus corticosteroids (prednisolone 30 mg daily for 5 days) 2
- Note: Dexamethasone may reduce praziquantel levels due to increased metabolism 2
- Artemisinin derivatives have been proposed as adjunctive therapy due to their greater impact on immature schistosomulae, but clinical trial evidence is lacking 2
Treatment Efficacy and Resistance Concerns
- Praziquantel has been the cornerstone of schistosomiasis control for over three decades 3
- Laboratory studies have demonstrated the potential for resistance development in S. mansoni under drug selection pressure 4
- Field isolates with reduced susceptibility to praziquantel have been reported, though confirmed clinical resistance remains rare 3
- Recent research suggests that ABC transporters in schistosomes may contribute to reduced drug susceptibility, and inhibiting these transporters can enhance praziquantel efficacy 5
Monitoring and Follow-up
- Serology may remain positive for many years after treatment and cannot be used to assess treatment success 1
- Stool and urine examination for eggs should be performed 3 months after treatment to confirm cure
- For patients with hepatosplenic disease: Monitor for development of portal hypertension and manage esophageal varices endoscopically 1
- For urogenital disease: Evaluate for bladder cancer and urinary obstruction 1
Important Caveats
- Praziquantel is primarily effective against adult worms but has limited activity against immature schistosomes, necessitating repeat treatment 6
- Corticosteroids should not be used without concurrent antiparasitic therapy
- Testing for endemic coinfections (Salmonella, HBV, HCV, HIV) is recommended as these may alter disease progression 1
- In areas of very low prevalence, more sensitive diagnostic methods like circulating cathodic antigen (CCA) or circulating anodic antigen (CAA) may be needed to detect low-burden infections 2
Treatment in Special Populations
- Pregnancy: Praziquantel is generally considered safe in pregnancy, especially in the second and third trimesters
- Immunocompromised patients: Standard dosing applies, but monitoring for treatment failure is essential
- Children: Dosing is the same as for adults, based on weight
Remember that while resistance concerns exist, praziquantel remains highly effective for most patients with schistosomiasis when administered at appropriate doses based on the infecting species.