Schistosomal Cystitis

Schistosomal cystitis is chronic inflammation of the bladder caused by the eggs of Schistosoma haematobium, which is acquired by skin contact with fresh water contaminated by infected snails (Bulinus species).

It is endemic across sub-Saharan Africa, including the Lake Victoria basin and the Kenyan coast, and in parts of the Middle East. School age children and young adults have the highest burden.

Chronic infection causes fibrosis, calcification, obstructive uropathy, secondary bacterial infection, bladder stones and squamous cell carcinoma of the bladder, a recognised carcinogenic effect of this parasite.

Pathophysiology. Adult worms live in the vesical venous plexus. Eggs penetrate the bladder wall to be passed in urine, and those that stay provoke granulomas, ulceration and haematuria.

Over years the granulomas heal with fibrosis and calcification of the bladder wall and ureters, giving contracture, ureteric stricture, hydronephrosis, vesicoureteric reflux, and sandy patches of calcified eggs under thin atrophic mucosa.

Terminal haematuria is the characteristic sign, with dysuria, frequency and suprapubic pain. Acute infection 2 to 8 weeks after exposure may cause swimmer's itch and a feverish illness with urticaria, cough and eosinophilia (Katayama syndrome). Late disease shows recurrent infection, loin pain, hydronephrosis, renal failure, bladder stones and hard bladder masses. Persisting haematuria, a mass, or a long history raises concern for carcinoma. Genital involvement causes haemospermia and pelvic pain.

• Urine microscopy for terminal spined eggs. Collect urine between 10:00 and 14:00, ideally after exercise, and examine the sediment or filter 10 mL. Repeat on 3 days if negative.
• Urinalysis for haematuria and proteinuria, culture, full blood count with eosinophils, creatinine.
• Serology (antibody) shows exposure but not active infection. Nucleic acid detection in urine is more sensitive where available.
• Ultrasound grades wall thickening, polyps, masses, calcification, bladder capacity and hydronephrosis. CT urography defines calcified bladder, ureteric strictures and tumour.
• Cystoscopy with biopsy for sandy patches, ulcers, masses and persistent haematuria. Squamous carcinoma may be present.
• HIV test, and stool for ova if intestinal species are possible.

Differential diagnosis.

• Bacterial cystitis
• Tuberculous cystitis
• Bladder carcinoma
• Bladder or ureteric calculus
• Eosinophilic cystitis
• Encrusted cystitis
• Glomerular haematuria
• Sickle cell haematuria

• Praziquantel 40 mg/kg orally as a single dose, or in two divided doses of 20 mg/kg 4 to 6 hours apart on one day, taken with food. Cure rates are about 60 to 90%, and egg counts fall in nearly all. Repeat once if eggs persist 4 to 6 weeks after treatment.
• Adverse effects are dizziness, abdominal pain, nausea and headache. Avoid in ocular cysticercosis without specialist input. Pregnancy and breastfeeding: treatment is generally given after weighing benefit, because untreated disease causes harm.
• Acute (Katayama) syndrome: praziquantel is deferred until 4 to 8 weeks after exposure, because early treatment does not kill immature worms. Severe illness: prednisolone 20 to 40 mg orally once daily for 5 days.
• Treat bacterial superinfection with culture directed antibiotics.
• Obstructive uropathy: ureteric stent or percutaneous nephrostomy for hydronephrosis with renal impairment or infection, endoscopic dilation or reimplantation for ureteric strictures after antiparasitic treatment.
• Bladder stones: endoscopic lithotripsy. Contracted bladder: augmentation cystoplasty in selected patients.
• Carcinoma: schistosomiasis associated squamous cell carcinoma needs radical cystectomy with pelvic lymph node dissection for muscle invasive disease, with systemic therapy directed by stage.
• Prevention: avoid fresh water contact in endemic areas, treat contacts and school populations in community programmes.

Special groups. Evidence of dosing and safety is limited in children under 4 years, so specialist advice is needed. Pregnancy: treatment after the first trimester where possible.

Monitoring. Urine eggs and haematuria at 4 to 6 weeks and 3 to 6 months. Ultrasound at 6 to 12 months to confirm regression of lesions. Haematuria that persists after cure, or any mass, needs cystoscopy and biopsy. Long term surveillance for squamous carcinoma in those with prolonged infection.

Referral and escalation. Refer to urology and infectious disease. Urgent referral for hydronephrosis, renal impairment, clot retention, or a suspicious mass.