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Urinary Schistosomiasis Literature Review Mahmoud Alameddine, MBBS Associate Consultant Urology International Medical Center

Urinary schistosomiasis

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Brief review about urinary schistomiasis in the Middle East

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Urinary SchistosomiasisLiterature Review

Mahmoud Alameddine, MBBSAssociate Consultant UrologyInternational Medical Center

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Urinary Schistosomiasis• Schistosomiasis is a chronic infection caused by the parasitic

trematodes of the genus Schistosoma.

• Human infection begins with free-swimming cercariae penetrating the skin and eventual development of the adult male and female worms.

• The paired adult worms reside in the venous plexuses of the abdominal viscera.

• S. mansoni and S. japonicum reside in the mesenteric veins, leading to gastrointestinal and/or hepatic disease.

• S. haematobium dwells principally in the perivesical venous plexus, resulting in urinary schistosomiasis

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S. haematobium egg: small spine at their terminal end

S. Mansoni egg : small spine at their lateral edge

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Epidemiology

• Of the 200 million persons affected with schistosomiasis, 80 to 90 million are infected with S. haematobium.  Engels et al, 2002

• As many as 10 to 40 million have obstructive uropathy or other complications secondary to this parasitic disease.  Engels et al, 2002

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Status of Control Program, WHO

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Progress achieved in the elimination of schistosomiasis from the Jazan region of Saudi Arabia.

Al Ghahtani AG, Amin MA. Ann Trop Med Parasitol. 2005

• Prevalence and intensity of Schistosoma haematobium infection in Jizan have been kept very low for several years.

• No infected snails can now be found in the region and new cases of human infection with S. haematobium are only being detected in border villages.

• The strategy to eliminate human infection based on: i. Case findingii. Treatment of infected individualsiii. Chemical and environmental control of freshwater snailsiv. Health educationv. Screening at primary-healthcare centres, by mobile teams

and at diagnostic units

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Pathogenesis and Pathology• Schistosomal disease results directly from the

granulomatous host response to schistosome eggs

• Microscopic examination of tissue shows edematous granulation tissue diffusely infiltrated by eosinophils, lymphocytes, and plasma cells

• On gross examination, the areas exhibit in large, bulky, hyperemic, and polypoid masses projecting into the lumen

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• In the active stage of disease, schistosomiasis is characterized by presence of viable eggs in urine or biopsy and multiple large inflammatory polyps.

• Inactive disease occurs after adult worms have died, and is characterized by the presence of “sandy patches” which is destroyed or calcified eggs and the tissues that undergo fibrotic reaction.

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Chronic Schistosomiasis• Is often complicated with obstructive uropathy

• The obstructive uropathy is usually asymmetric.

• The location of the obstruction varies from:i. The urethral meatus (1%), ii. Interstitial ureter (10% to 30%)iii. Juxtavesical ureter (20% to 60%) iv. Lower third of the ureter (15% to 50%)v. Combination of these areas (30% to 60%)

• Left untreated, schistosomal hydronephrosis advances to progressive renal impairemnt.

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Bladder cancer

• Is the final pathologic sequelae of schistosomiasis

• High frequency of squamous cell carcinomas (60% to 90%), with 5% to 15% adenocarcinomas 

• More than 40% of schistosomiasis-associated squamous cell carcinomas of the bladder are well-differentiated that are exophytic and carry an overall good prognosis

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Clinical Manifestations

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• Hematuria and terminal dysuria is the first sign of established S. haematobium infection, often appearing 10 to 12 weeks after infection 

• Katayama fever (in S. Japonicum):  fever, lymphadenopathy, splenomegaly, eosinophilia, urticaria.

• Involvement of these genital structures often present with scrotal pain or a testicular mass

• Over time, a late, chronic, active stage developes “schistosomal contracted bladder” consistent with pelvic pain with associated urinary urgency, frequency, and incontinence.

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• Patients finally enter a chronic inactive phase, in which viable eggs are no longer detected in urine or tissues

• This stage are caused by sequelae of the immune reaction to the eggs rather than the schistosomal infection itself

• Silent obstructive uropathy may develop throughout this phase as fibrosis replaces polypoid lesions and the bladder and ureters undergo irreversible damage

• Unfortunately,  40% to 60% present to us at this stage of their disease

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Diagnosis• The presence of eggs in the urinary sediment is diagnostic.• If eggs are not found in the urine, a bladder biopsy should

be attempted.

• Serology tests of the blood that combine a FAST-ELISA followed by Western blot analysis are available.

• But they do not distinguish between acute and chronic disease. Antibody titers can remain positive even after curative treatment.

• Real-time PCR of the urine is in developmental testing, and may hold some promise in the future

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• Since early diagnosis of pre-cancerous conditions associated with urinary schistosomiasis could save countless lives, studies are being carried out to find non-invasive methods to detect schistosome-based bladder cancer

• A variety of tumor markers have been studied in urine specimens.

e.g. Aberrant Methylation of RARb2 and APC Genes in Voided Urine

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Treatment

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Medical Treatment• All patients with schistosomiasis should be treated

regardless of the intensity or apparent activity of their infection

• Praziquantel is the drug of choice for all schistosoma species.• The recommendation is 2 oral doses of 20 mg/kg (or a single

40 mg/kg dose)

•  Cure rates are from 73% to 100%

• Praziquantel is extremely well tolerated• The lack of serious side effects has made it an excellent

agent of choice in mass chemotherapy campaigns

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Surgical Treatment• Anatomic ureteral stenosis, with or without calculi, has

been identified in up to 80% of obstructions.  (El-Nahas et al, 2003)

• when there is residual ureteral stenosis after successful chemotherapy it is usually amenable to surgical intervention.

• Depending on the extent and location of the stricture (excision or dilatation)

• Balloon dilatation has reportedly proved effective but frequently followed by repeat stenosis.

• The best outcome is ureteral reimplantation (Leadbetter -Politano operation)

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• In long or multisegmental lesions, excision of the affected portion leaves an inadequate residual ureter for reimplantation.

• Boari flap, ileal interposition or long-term nephrostomy drainage can be done

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Can schistosomiasis be eliminated?

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• Schistosomiasis is being successfully controlled in many countries but remains a major public health problem, with an estimated 200 million people infected, mostly in Africa.

• Constraints to control include, the lack of political commitment and infrastructure for public health interventions in some countries.

• Anti-schistosomal drugs are expensive and the cost of individual treatment is a high proportion of the per capita drug budgets.

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THANK YOU FOR YOUR ATTENDANCE