What are the signs and symptoms of schistosomiasis?

Signs and Symptoms of Schistosomiasis

Schistosomiasis presents with distinct clinical manifestations that vary by infection stage and species, ranging from acute Katayama syndrome in newly exposed travelers to chronic intestinal or urogenital disease in endemic populations. 1

Acute Schistosomiasis (Katayama Syndrome)

This syndrome occurs 2-8 weeks after freshwater exposure in newly infected travelers and represents an immunologically-mediated hypersensitivity reaction during parasite migration and egg-laying phases. 2, 3

Key features include:

• Fever (prominent systemic symptom) 2, 1
• Dry cough and respiratory symptoms 2, 1
• Urticarial rash (itchy, raised skin lesions) 2, 1
• Diarrhea 2, 1
• Headache 2, 1
• Marked eosinophilia, sometimes exceeding 5 × 10⁹/L, though occasionally absent 2
• Nodules and infiltrates on chest radiograph 2

The combination of eosinophilia with fever and rash 2-8 weeks after freshwater swimming in endemic areas (particularly Africa) makes the diagnosis highly likely and justifies empirical treatment even when serology and microscopy are negative. 2, 1

Chronic Intestinal Schistosomiasis (S. mansoni, S. japonicum)

Intestinal disease develops as eggs become trapped in mesenteric vessels and surrounding tissues, triggering granulomatous inflammation. 4

Gastrointestinal manifestations:

• Chronic or intermittent abdominal pain 1, 5
• Nausea and meteorism (abdominal bloating) 5
• Diarrhea, with or without blood 1, 3
• Bloody diarrhea and rectal tenesmus in active disease 5
• Weight loss 1

Hepatosplenic complications:

• Hepatosplenomegaly 5, 6
• Hepatic fibrosis and portal hypertension (from egg deposition in portal vessels) 1, 3
• Splenomegaly (correlates with infection intensity) 6
• Variceal bleeding (from portal hypertension) 3

Heavy infections can cause dysenteric illness, intestinal obstruction, or gastrointestinal bleeding. 1

Chronic Urogenital Schistosomiasis (S. haematobium)

Urogenital disease results from eggs deposited in pelvic veins, particularly affecting the bladder and urinary tract. 3, 4

Urinary manifestations:

• Hematuria (blood in urine—the hallmark symptom) 1, 3, 6
• Dysuria (painful urination) 1, 3
• Burning micturition 6
• Proteinuria 1, 6

Reproductive system involvement:

• Hematospermia (blood in semen) 1
• Inter-menstrual bleeding in women 1

Complications:

• Renal obstructive lesions (2-3 times more common in moderate-to-heavy infections) 6
• Bladder wall lesions (far more frequent with moderate-to-heavy infections) 6
• Renal failure 3
• Squamous-cell carcinoma of the bladder (long-term complication) 3

Neuroschistosomiasis

CNS involvement occurs when eggs reach the brain or spinal cord, either through anomalous adult worm migration or egg embolization from the portal-mesenteric system. 7

Neurological presentations:

• Signs and symptoms of increased intracranial pressure (from mass effect of concentrated eggs and large granulomas) 7
• Focal neurological signs (depending on lesion location) 7
• Rapidly progressing transverse myelitis, usually affecting lumbosacral spinal cord segments 7
• Seizures and headache (from space-occupying lesions) 7

Most CNS involvement associated with chronic hepatosplenic or cardiopulmonary forms is asymptomatic due to sparse, random egg distribution. 7

Important Clinical Considerations

Helminth infections, including schistosomiasis, are frequently asymptomatic, particularly in endemic populations with chronic low-level infections. 2

Eosinophilia is a key diagnostic finding, especially in acute infection, though it may be absent in some cases. 2, 1

Consider schistosomiasis in migrants and travelers from endemic regions (Middle East, Southeast Asia, Latin America, sub-Saharan Africa) presenting with eosinophilia, even without classic symptoms. 1, 3, 4

Common Diagnostic Pitfalls

• Colonoscopic findings in intestinal schistosomiasis can mimic inflammatory bowel disease, making differential diagnosis challenging 5
• Serology may remain negative during the first 4-8 weeks post-infection (and can take up to 22 weeks to become positive), so negative results don't exclude acute disease 1
• Symptoms may worsen despite negative initial microbiologic studies, requiring high clinical suspicion and repeat testing 5