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Bladder & urothelial tract

Cystitis

Schistosomiasis (bilharziasis)

Author: Y. Albert Yeh, M.D., Ph.D.

Editor-in-Chief: Debra L. Zynger, M.D.

Last author update: 3 February 2022

Last staff update: 10 November 2023

Copyright: 2003-2025, PathologyOutlines.com, Inc.

PubMed Search: Schistosomiasis bladder

See Also: Parasitology chapter

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Table of Contents

Cite this page: Yeh YA. Schistosomiasis (bilharziasis). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladderschistosomiasis.html. Accessed April 3rd, 2025.

Definition / general

Parasitic infection of the bladder with blood flukes (trematodes), Schistosoma species (mainly Schistosoma haematobium)

Essential features

Bladder schistosomiasis is most commonly caused by Schistosoma haematobium
Eggs of Schistosoma haematobium: 110 - 170 μm, oval with terminal spine
Eggs of Schistosoma mansoni: 115 - 175 μm, oval with lateral spine
Few case reports of bladder schistosomiasis caused by Schistosoma mansoni and Schistosoma haematobium - Schistosoma mansoni hybrid (Emerg Infect Dis 2019;25:365)
Coinfection with Schistosoma haematobium and Schistosoma mansoni occurs (East Afr Med J 2013;90:36)

Terminology

Bladder bilharziasis is named after Theodor Bilharz, a German physician who discovered the first blood fluke causing urinary schistosomiasis in 1851 (Wikipedia: Schistosomiasis [Accessed 9 February 2022])
Bladder schistosomiasis
Genitourinary schistosomiasis
Schistosomiasis related cystitis

ICD coding

ICD-10: B65.0 - schistosomiasis due to Schistosoma haematobium [urinary schistosomiasis]

Epidemiology

Endemic in Africa and the Middle East (Nat Rev Dis Primers 2018;4:13)
Transmission in the Nile River valley in Egypt and Mahgreb area in North Africa
Recent focus of infection in Corsica, France (Trends Parasitol 2017;33:600)

Pathophysiology

After penetration of skin or mucous membranes, schistosomulae migrate through the lungs to portal venous system and mature into adults
About 6 weeks later, adult worms migrate to bladder venules (Nat Rev Dis Primers 2018;4:13)
Females lay eggs that reach the bladder wall, penetrate bladder mucosa and excrete into urine
Bladder wall shows eggs and mixed inflammatory reaction with lymphocytic, neutrophilic and eosinophilic infiltrate and scarring of the vesicular vessels
Parasitic eggs provoke chronic granulomatous inflammation with calcifications and fibrotic thickening of the bladder wall, deposits of calcified eggs in later stage (Nat Rev Dis Primers 2018;4:13)
Eggs may block drainage of urine into the bladder, causing hydroureter
May develop secondary bacterial urinary tract infections, renal failure and pulmonary hypertension (Hum Pathol 1986;17:333)
May progress to bladder cancer (squamous cell carcinoma [80 - 85%], adenocarcinoma [5 - 15%] and rarely urothelial carcinoma) (Front Med (Lausanne) 2018;5:223)

Etiology

Humans are infected with schistosomes after exposure to cercariae released by snails (Bulinus species) in fresh water
Penetration of skin or mucous membranes by cercariae (survives 3 - 4 days in fresh water)
Schistomulae migrate to bladder plexus and nearby veins and venules (Nat Rev Dis Primers 2018;4:13)
Female schistomulae deposit their eggs
Some eggs reach the bladder wall, penetrate bladder mucosa and excrete in urine
Eggs hatch and release miracidia
Miracidia penetrate snail intermediate hosts (Bulinus species)
After 2 generations of sporocysts, the snails produce cercariae and release them in fresh water (CDC: Parasites - Schistosomiasis [Accessed 9 February 2022])

Diagrams / tables

Images hosted on other servers:

Life cycle

Clinical features

Swimmer's itch: cercarial dermatitis (days after infection)
- Local erythema, pruritic maculopapular rash
Acute schistosomiasis (2 - 8 weeks after infection) (Lancet Infect Dis 2007;7:218)
- Katayama syndrome: fever ("snail fever"), cough, muscle pain, malaise, abdominal pain
- Hematuria, dysuria, suprapubic pain, urinary tract infections
Chronic schistosomiasis (within months after infection)
- May progress to hydroureter, hydronephrosis, chronic kidney disease and bladder cancer (J Egypt Soc Parasitol 2017;47:211)
- May progress to bladder carcinoma, known as carcinogen (group 1) related to bladder cancer (Front Med (Lausanne) 2018;5:223)

Diagnosis

Detection of Schistosoma haematobium or Schistosoma mansoni eggs in urine samples or bladder tissues (J Egypt Soc Parasitol 2017;47:211)
Schistosoma haematobium eggs: 110 - 170 μm × 40 - 70 μm, oval with terminal spine (Hum Pathol 1986;17:333)
Schistosoma mansoni eggs: 115 - 175 μm × 45 - 47 μm, oval with lateral spine

Laboratory

Detection of Schistosoma specific antibody in serum or urine by enzyme linked immunosorbent assay (ELISA) (Parasitol Res 2011;108:1457)
Detection of schistosome DNA or RNA by PCR (real time PCR or multiplex PCR) (Clin Microbiol Rev 2015;28:939)

Radiology description

For bladder schistosomiasis: bladder wall thickening (usually > 4 mm) on ultrasound
For carcinoma arising in bladder schistosomiasis: focal bladder wall thickening or mass on ultrasound

Prognostic factors

Good prognosis for patients with early disease
Prognosis is worse for chronic infections with complications:
- Immune complex glomerulonephritis
- Obstructive nephropathy
- Obstructive uropathy
- Chronic pyelonephritis
- Amyloidosis
- Bladder cancer (risk 1.72, further increased in smokers)
References: J Adv Res 2013;4:453, Nat Rev Dis Primers 2018;4:13

Case reports

5 year old girl with Schistosoma haematobium in urine (Front Pediatr 2018;6:14)
14 year old boy with Schistosoma haematobium - Schistosoma mansoni hybrid parasite (Emerg Infect Dis 2019;25:365)
25 year old man with Schistosoma haematobium in bladder biopsy (BMC Clin Pathol 2018;18:13)
26 year old man with Schistosoma haematobium (Indian J Pathol Microbiol 2017;60:614)
67 year old man with bladder urothelial carcinoma and Schistosoma mansoni (Int J Surg Case Rep 2015;13:76)

Treatment

Single course of praziquantel treatment can be curative
Corticosteroids (severe disease), metrifonate (alternative therapy) for bladder schistosomiasis (ChemMedChem 2018;13:2374)

Gross description

Early active stage: erythematous, sessile or pedunculated polyps, "grainy sandy" patches (Urology 2017;107:e7)
Chronic stage: fibrotic thickening of bladder wall, stellate ulcers, tumor-like lesions (Hum Pathol 1986;17:333)

Microscopic (histologic) description

Bladder mucosa with ulceration, necrosis and mixed inflammatory infiltrate of lymphocytes, neutrophils and eosinophils (Hum Pathol 1986;17:333)
Calcified eggs with chronic granulomatous inflammation detected in the bladder mucosa and muscularis (BMC Clin Pathol 2018;18:13)
Calcified eggs measure approximately 120 - 170 μm with terminal spine (Schistosoma haematobium) or lateral spine (Schistosoma mansoni) (Clin Microbiol Rev 2015;28:939)
Flattening of bladder mucosa with keratinizing squamous cell metaplasia or intestinal metaplasia (Hum Pathol 1986;17:333)
Fibrosis with thickening of the bladder wall (Hum Pathol 1986;17:333)
Infiltrating dysplastic squamous cells with keratinization present in schistosomiasis associated squamous cell carcinoma

Microscopic (histologic) images

Contributed by Y. Albert Yeh, M.D., Ph.D., Susan Prendeville, M.D. and Kiran Alam, M.D., Anshu Jain, M.D.,
Veena Maheshwari, M.D., Farhan A. Siddiqui, M.B.B.S., Ershadul Haq, M.B.B.S., M.D. and @ThatGlassTho on Twitter

Calcified eggs and keratin

Schistosoma eggs and keratin

Schistosoma eggs with terminal spine

Bladder calcified eggs

Calcified eggs with cracks

Parasitic calcified eggs

Dysplastic keratinizing squamous cells

Malignant squamous cells

Malignant squamous cells with intercellular bridges

Schistosoma haematobium eggs

Schistosoma eggs in ureter

Ureter with Schistosoma eggs

Muscularis propria with Schistosoma eggs

Schistosoma eggs

Schistosomiasis (bilharziasis)

Cytology description

Uncommon in urine but if present, may show an oval calcified egg with a lateral or terminal spine

Cytology images

Contributed by Y. Albert Yeh, M.D., Ph.D.

Calcified eggs in urine

Schistosoma egg with lateral spine

Positive stains

Schistosoma mansoni and Schistosoma japonium egg shells: acid fast (Am J Trop Med Hyg 1954;3:1066)

Negative stains

Schistosoma haematobium egg shells: acid fast

Molecular / cytogenetics description

Molecular testing of schistosome eggs in Africa showed hybrids of Schistosoma haematobium and livestock schistosoma species, S. mattheei and S. bovis (Emerg Infect Dis 2019;25:1245)
Common chromosomal aberrations in schistosomiasis associated bladder cancer (Carcinogenesis 2000;21:1721)
- Loss: 8p, 18q, 17p, 5q, 9p, 10q, 11q, 18p, 11p, 9q, 20p, 6q (in descending order)
- Gain: 17q, 5p, 7q, 7p, 1q (in descending order)
Most common genetic alterations in schistosomiasis associated bladder cancer (Nat Clin Pract Urol 2005;2:502)
- Low grade urothelial carcinoma: chromosome 9 loss of heterozygosity, FGFR3 activating mutation
- Dysplasia and carcinoma in situ: TP53 mutations, chromosome 9 loss of heterozygosity
Loss of heterozygosity in schistosomiasis associated bladder cancer versus non schistosomiasis associated bladder cancer (J Natl Cancer Inst 1995;87:1383)
- 9p loss of heterozygosity (twofold higher in schistosomiasis associated bladder cancer)
- 9q loss of heterozygosity (threefold lower in schistosomiasis associated bladder cancer)
Genes involved in schistosomiasis associated bladder cancer (Clin Microbiol Rev 1999;12:97)
- Mutation of FGFR3 (> 30%, more frequent in low grade papillary tumors)
- Activation of HRAS (7 - 17%, more frequent in low grade papillary tumors)
- Homozygous deletions of p16INK4A (more common in high grade Ta tumors) (Am J Pathol 1999;155:105)
- Inactivation of tumor suppressor genes TP53 and RB (more common in carcinoma in situ and high grade invasive tumors)
- Overexpression of ERBB2 in advanced urothelial carcinoma
- BCL2 expression in later stages of squamous cell carcinoma

Sample pathology report

Urinary bladder, dome, biopsy:
- Urothelial mucosa with ulcerations, chronic granulomatous inflammation with eosinophils and calcified parasitic eggs, consistent with schistosomiasis related cystitis (see comment)
- Comment: The urothelial mucosa shows urothelial mucosa with granulation tissue and mixed inflammatory infiltrate composed predominantly of lymphocytes, neutrophils and eosinophils. There are many calcified oval parasitic eggs measuring approximately 120 microns with a sharp terminal spine. These changes of cystitis are consistent with Schistosoma haematobium infection. A small fragment of the muscularis propria is also present in the biopsy specimen.

Differential diagnosis