What are the symptoms and treatment options for schistosomiasis?

Symptoms of Schistosomiasis

Schistosomiasis presents with distinct clinical manifestations that vary by infection stage: acute symptoms occur 2-8 weeks after exposure with fever and rash, while chronic disease causes organ-specific symptoms depending on the infecting species—urinary symptoms with S. haematobium and gastrointestinal symptoms with intestinal species. 1

Acute Schistosomiasis (Katayama Syndrome)

Timing and Presentation:

• Occurs 2-8 weeks after freshwater exposure in newly infected travelers 1
• Key symptoms include:
  • Fever 1
  • Dry cough 1
  • Urticarial rash 1
  • Diarrhea 1
  • Headache 1
• Eosinophilia is a key laboratory finding during acute infection 1

Diagnostic Consideration:

• The combination of eosinophilia with fever and rash after freshwater swimming in endemic areas makes the diagnosis likely even if serology and microscopy are initially negative 1
• Serology becomes positive at 4-8 weeks post-infection but may take up to 22 weeks 1

Chronic Intestinal Schistosomiasis

Gastrointestinal Manifestations (S. mansoni, S. japonicum, S. intercalatum, S. mekongi):

• Chronic or intermittent abdominal pain 1
• Weight loss 1
• Diarrhea 1
• Heavy infections can cause:
  • Dysenteric illness 1
  • Intestinal obstruction 1
  • Gastrointestinal bleeding 1

Hepatosplenic Disease:

• Results from granulomatous inflammation around eggs trapped in liver tissue 2
• Leads to intrahepatic presinusoidal portal hypertension 3
• Esophageal and gastric varices are important causes of morbidity and mortality 3

Chronic Urinary Schistosomiasis

Genitourinary Manifestations (S. haematobium):

• Hematuria (blood in urine) 1
• Proteinuria 1
• Dysuria (painful urination) 1
• Hematospermia (blood in semen) 1
• Inter-menstrual bleeding in women 1

Diagnostic Approach:

• Microscopy of nitrocellulose-filtered terminal urine detects eggs 1
• Urine dipstick for microscopic hematuria and proteinuria has low sensitivity 1

Neuroschistosomiasis

Central Nervous System Involvement:

• Spinal cord disease (most common with S. mansoni and S. haematobium):

  • Gradual onset paraplegia 1
  • Transverse myelitis 1
  • MRI showing spinal cord enlargement with contrast enhancement 1

• Cerebral disease (most common with S. japonicum):

  • Focal neurological signs 1
  • Seizures 1
  • Mass lesions on MRI with contrast enhancement 1
  • Altered consciousness in acute cases 1

Diagnostic Challenge:

• CSF eosinophilia is present in less than 50% of cases 1
• Serology is often negative 1
• A trial of treatment may be warranted even with negative serology in suspected cases 1

Chronic Complications

Long-term Sequelae:

• Fibrosis and calcification at sites of egg entrapment 2
• Deposition of schistosomal antigen-antibody complexes in renal glomeruli 2
• Secondary amyloidosis 2
• Malignancy may complicate chronic lesions in the urinary bladder or colon 2

Co-infections:

• Salmonella co-infection may confound the clinical picture 4, 2
• Hepatitis B or C co-infection results in liver disease that progresses more rapidly and is more difficult to treat 3

Diagnostic Workup

Initial Testing:

• Complete blood count to check for eosinophilia 1
• Serology for schistosomiasis 1
• Stool and urine samples for microscopy and/or PCR 1
• Abdominal ultrasound to assess hepatosplenic involvement and portal hypertension 1

Advanced Imaging:

• Chest radiograph may show nodules and infiltrates in acute schistosomiasis 1
• MRI with contrast for suspected neuroschistosomiasis 1

Treatment

Standard Therapy:

• Praziquantel is the drug of choice for all forms of schistosomiasis 5
• For S. mansoni, S. intercalatum, and S. guineensis: Praziquantel 40 mg/kg orally as a single dose 5
• For S. japonicum and S. mekongi: Praziquantel 60 mg/kg orally in two divided doses 5
• Repeat dose at 6-8 weeks after initial treatment, as immature schistosomules are relatively resistant to initial treatment 5

Acute Schistosomiasis Management:

• Prednisolone 20-30 mg daily for 5 days to reduce symptom duration 5
• Praziquantel should be administered after the acute inflammatory phase 5
• Critical pitfall: Administering praziquantel during acute Katayama syndrome without steroids may worsen symptoms 5

Neuroschistosomiasis:

• Praziquantel 40 mg/kg twice daily for 5 days 5
• Combined with dexamethasone 4 mg four times daily, reducing after 7 days, for a total of 2-6 weeks 5
• In acute neuroschistosomiasis, corticosteroids should be given first, before anthelmintic therapy 5

Important Caveat:

• Consider potential co-infection with strongyloidiasis before starting corticosteroids, which could precipitate hyperinfection syndrome 5