What are the clinical features of schistosomiasis?

Clinical Features of Schistosomiasis

Schistosomiasis presents with distinct clinical manifestations that vary by infection stage and species, progressing from acute Katayama syndrome through chronic organ-specific disease to potentially severe complications including hepatic fibrosis, portal hypertension, and bladder malignancy. 1, 2

Acute Schistosomiasis (Katayama Syndrome)

Acute schistosomiasis occurs 2-8 weeks after freshwater exposure in newly infected travelers, presenting as a hypersensitivity reaction to migrating schistosomules 1, 2. This stage is species-independent and more common in infection-naïve individuals 3.

Key Clinical Features:

• Fever (often high-grade) 1, 3
• Dry cough and respiratory symptoms 1
• Urticarial rash (pruritic, migratory) 1, 3
• Diarrhea (may be bloody) 1
• Severe headache 1
• Marked eosinophilia on complete blood count 1

Chest radiograph may show nodules and infiltrates during this acute phase 1. The combination of fever, rash, and eosinophilia after freshwater swimming in endemic areas makes the diagnosis highly likely even with negative initial testing 1.

Chronic Intestinal Schistosomiasis

Chronic intestinal disease develops after worm maturation and egg deposition, primarily affecting the colon and rectum with S. mansoni, S. japonicum, S. intercalatum, and S. mekongi 1, 3.

Gastrointestinal Manifestations:

• Chronic or intermittent abdominal pain 1, 3
• Diarrhea (with or without blood) 1, 2
• Weight loss 1
• Dysenteric illness in heavy infections 1
• Intestinal obstruction (rare complication) 1
• Gastrointestinal bleeding 1

Hepatosplenic Complications:

• Hepatic fibrosis due to granuloma formation around trapped eggs 1, 3, 2
• Portal hypertension with resultant splenomegaly 2
• Variceal bleeding from esophageal varices 2
• Hepatosplenomegaly detectable on abdominal ultrasound 1

Abdominal ultrasound is essential for assessing hepatosplenic involvement and portal hypertension in chronic cases 1.

Urogenital Schistosomiasis

Urinary schistosomiasis, caused primarily by S. haematobium, affects the lower urinary tract with egg deposition in bladder and ureteral walls 1, 3.

Urinary Tract Features:

• Hematuria (often terminal, microscopic or macroscopic) 1, 2
• Dysuria and painful urination 1, 2
• Proteinuria 1
• Hematospermia in males 1
• Inter-menstrual bleeding in females 1

Severe Complications:

• Renal failure from chronic ureteral obstruction 2
• Squamous-cell carcinoma of the bladder (late malignant transformation) 3, 2
• Hydronephrosis from ureteral fibrosis 3

Neuroschistosomiasis

CNS involvement results in myelitis or cerebral disease, representing a severe manifestation requiring urgent recognition 4, 5.

Spinal Cord Involvement:

• Gradual onset paraplegia (most common with S. mansoni and S. haematobium in Africa) 4
• Transverse myelitis 4
• MRI shows spinal cord enlargement with contrast enhancement in acute phase 4

Cerebral Involvement:

• Focal neurological signs (most common with S. japonicum in Southeast Asia) 4
• Seizures 4
• Mass lesions on MRI with contrast enhancement 4
• Altered consciousness in acute neuroschistosomiasis 4
• CSF eosinophilia in less than 50% of cases 4

Peripheral eosinophilia may be absent in neuroschistosomiasis, and serology is often negative, making diagnosis challenging 4.

Ectopic Manifestations

Secondary manifestations can occur in multiple organ systems beyond the primary sites 3.

Pulmonary Involvement:

• Pulmonary nodules visible on chest imaging 1
• Infiltrates during acute infection 1
• Pulmonary hypertension (rare, from egg embolization) 3

Renal Complications:

• Glomerulonephritis from immune complex deposition 3
• Secondary amyloidosis in chronic disease 3

Diagnostic Pearls and Pitfalls

Eosinophilia is a key finding, especially in acute infection, but may be absent in chronic or CNS disease 1, 4. Serology becomes positive 4-8 weeks post-infection but may take up to 22 weeks, and shows cross-reactivity with other helminths 1.

Common Diagnostic Pitfalls:

• Negative microscopy does not exclude disease—serology and clinical context are critical 1
• Persistent symptoms with positive serology warrant endoscopy with biopsy or advanced imaging 1
• In suspected neuroschistosomiasis, a trial of treatment may be warranted even with negative serology 4
• Co-infection with Salmonella, hepatitis B/C, malaria, or HIV can confound the clinical picture 3

The racial and genetic background of the host influences acute manifestations, with infection-naïve travelers experiencing more severe Katayama syndrome than endemic populations 3.