Urinary schistosomiasis: a case of late presentation

Abstract

A man in his early 20s, originally from north-central Africa, presented with a high incidental serum creatinine level. A non-contrast CT scan was taken which was suggestive of urinary schistosomiasis. The diagnosis was confirmed on obtaining biopsies from the bladder. Due to bilateral hydronephrosis, an attempt at bilateral renal decompression was made. This failed to improve renal function. He eventually underwent a right nephrectomy. He is in end-stage renal failure, undergoing long-term dialysis, and has been placed on the waiting list for renal transplant.

Background

Urinary schistosomiasis is caused by the parasitic flatworm Schistosoma haematobium, and is endemic to the Middle East, 53 African countries and Corsica, where it causes significant morbidity.¹ After malaria, schistosomiasis is the second most common socioeconomically devastating tropical parasitic disease.² Schistosomiasis is receiving attention again in view of its increasing prevalence in European countries.³ It is therefore vital to obtain a travel history and investigate accordingly in patients presenting with haematuria and with a history of visiting an endemic country. It is also worth considering screening patients arriving from endemic countries.¹

Case presentation

A man in his early 20s was referred from a primary care unit, being found to have a plasma creatinine of 1122 µmol/L and an estimated glomerular filtration rate of 5 mL/min/1.73 m² on routine blood testing. He had been residing in a European country for 1 year, prior to which he had lived in north-central Africa. On presentation, he had no haematuria; however, he reported dysuria and mild, generalised abdominal pain. It should be noted that eosinophilia, which is often, although not always present in schistosomiasis, was absent.⁴

An ultrasound of the kidneys showed severe bilateral hydronephrosis and cortical thinning. Dialysis was initiated followed by attempts at bilateral renal decompression. Retrograde stenting was performed. A stricture in the left distal ureter was stented successfully; however, stenting failed on the right side. A right nephrostomy was therefore performed.

A CT scan of the kidneys, ureters and bladder indicated the diagnosis. This showed severe ureterohydronephrosis bilaterally, associated with severe thinning of the renal parenchyma, peripheral calcifications along the margin of the kidney and along both ureters. The urinary bladder was irregular in shape and had thick calcified walls. All findings were suggestive of urinary schistosomiasis.

The diagnosis was confirmed following rigid cystoscopy with bladder biopsies. Histopathological studies reported vast areas of haemorrhage, florid cystitis cystica and numerous calcified S. haematobium eggs within the stroma. The diagnosis was re-enforced by means of urine microscopy which showed the presence of Schistosoma ova in the urine.

The patient was treated with a single dose of praziquantel 40 mg/kg.

An attempt to insert an antegrade stent on the right side failed. A right nephrostogram was performed which showed right distal ureteric stricture with no passage of contrast distally. A dimercaptosuccinic acid (DMSA) renal scan showed very poor renal function bilaterally, despite having previously undergone bilateral renal decompression.

A right nephrectomy was eventually performed in order to avoid the formation of fistulas following the long-term right nephrostomy. Following surgery, his management focused on continuing long-term renal replacement therapy. He is a candidate for a kidney transplant.⁵

Investigations

Ultrasound of the kidneys, ureters and bladder

Ultrasound is a vital investigation, showing evidence of obstruction of the urinary system evidenced by hydronephrosis and hydroureters. Cortical thinning was seen which indicated renal scarring and decreased amount of functional tissue.

CT scan of the kidneys, ureters and bladder

Confirmed cortical thinning, showed peripheral calcifications along the kidney and ureters, and highlighted an irregular bladder with thick calcified walls, all of which suggested urinary schistosomiasis (figure 1).

Figure 1.

A non-contrast CT scan showing the irregular shape and thick, calcified walls of the urinary bladder.

Rigid cystoscopy

Provided biopsies of the urinary bladder and confirmed the diagnosis of urinary schistosomiasis with certainty (figures 2 and 3).

Figure 2.

An image taken during cystoscopy, showing thickened bladder walls and granulomas.

Figure 3.

Histopathological image of the bladder biopsy showing ova of Schistosoma haematobium.

Urine microscopy

Ova of S. haematobium, seen in the urine under direct vision with a microscope, further confirmed the diagnosis.

Nephrostogram

An X-ray procedure aimed at determining the flow of urine through the ureter showed obstruction of flow at the right distal ureter, with proximal dilatation (figure 4).

Figure 4.

A nephrostogram showing obstruction of flow of contrast at the right distal ureter due to a stricture, with dilation proximal to the obstruction.

DMSA scan

DMSA scan showed evidence of poor renal function, despite renal decompression, thus providing a prognosis for long-term renal replacement therapy.

Serological testing (not used in the above case)

IgG antibody testing to Schistosoma spp: a positive test confirms the presence of Schistosoma, however it cannot differentiate between Schistosoma spp.⁶

PCR testing may detect DNA sequences specific to the Schistosoma spp obtained from the ova present in urine and isolated by filtration through filter paper.⁷

Treatment

The medical management of urinary schistosomiasis involves the administration of a single oral dose of the anthelmintic drug praziquantel at 40 mg/kg. The antimalarial artesunate has been trialled in the treatment of urinary schistosomiasis, leading to inconsistent results and showing a substantial effect in only one of three trials.⁸

Surgical management involves resection of endovesical lesions, which provides samples for histopathological analysis, while also reducing haematuria. Coagulation or resection procedures may be applied for ulcers. Tumours arising from changes due to Schistosoma infection should be deeply resected; however, care should be taken not to perforate the bladder. Bladder neck stenosis may be present which may result in high-pressure vesicoureteric reflux. This is treated with incision or transurethral resection. In the case of ureteral stenosis, ileal ureteral replacement is the procedure of choice as this ensures revascularisation and ensures that the transplant is free from parasitic colonisation.³

Balloon dilatation and ureterocystoneostomies are generally avoided in the case of ureteral stenosis as these are generally met with a high failure rate.³

Outcome and follow-up

Despite best efforts, attempts at renal decompression failed, leading to an outcome of long-term renal replacement therapy. He currently awaits a donated kidney to become available and will be a candidate for kidney transplant once a correctly matched donor becomes available. He will continue to be followed up by routine cystoscopies because of a risk of developing bladder squamous cell carcinoma (SCC).

Discussion

Schistosomiasis or Bilharziasis is caused by a trematode of the genus Schistosoma with the four main infecting organisms being S. haematobium, S. japonicum, S. mansoni and S.mekongi.³

The life cycle of the organism begins when the ova are excreted by the host mammal in urine or faeces. These hatch, releasing miracidia, ciliated non-feeding larvae,⁹ which penetrate snail tissue and produce sporocysts within the snail which acts as an intermediate host. Cercariae, free swimming mobile larvae, are released from the snail into water.¹⁰ Mammals are then infected through contact with the water and direct penetration of the skin,¹⁰ following which the cercariae lose their tails to become schistosomulae.¹¹ These mature in the host portal vasculature, where they may remain for 3–5 years,¹² following which they migrate to the target organs, mainly urinary bladder, rectum and colon.¹³

Symptoms of parasitisation commonly include haematuria, dysuria and dysentery, most of which were strikingly absent in the case discussed.² The case discussed highlights a deviation from the standard presentation of urinary schistosomiasis, with the rare presentation of obstructive uropathy at the forefront of signs, and dysuria and mild abdominal discomfort the only symptoms experienced.

Other symptoms include Swimmer’s itch which involves local inflammation and itching at the site of penetration of the parasite.² Bronchopneumonia may occur during migration of the schistosomulae through the pulmonary capillaries manifesting as bronchial hyper-reactivity and pulmonary infiltrates which may be seen radiologically.² Katayama syndrome is a delayed hypersensitivity reaction and occurs 4 weeks after infiltration of the parasite. This presents as fever, myalgias and a vesicular rash, coinciding with the mature phase of the life cycle of the worms and may progress to hepatic fibrosis, splenomegaly and portal hypertension.²

In the urinary system, schistosomiasis causes a predominantly granulomatous inflammatory process which mainly involves the distal third of the ureters, the bladder and the urethra.¹⁴ In the long term, this results in calcification causing hydroureters and hydronephrosis. In the bladder wall, granulomas form and fine mucosal tubercles, referred to as sandy patches, develop.¹⁴ The patchy nature of these lesions results in fibrosis of otherwise normal surrounding tissue, leading to a pathological picture referred to as cystitis cystica.¹⁴

An increased risk of SCC of the bladder is attributed to urinary tract infection by S. haematobium. This is attributed to an increase in bacterial infection that mediates nitration reactions thus producing nitroso (N)-nitrosamines.¹⁵ It is the prolonged exposure to N-nitrosamines, together with chronic inflammation, which is believed to result in production of oxygen radicals and damage to host cell DNA, leading to carcinoma.¹⁵ Despite no screening programme for bladder cancer at present, it may be justified for patients with urinary schistosomiasis to undergo routine cystoscopy to screen for the development of SCC of the bladder.

The treatment of schistosomiasis is relatively straightforward if the diagnosis is made early in the infective process, and early treatment with praziquantel can lead to full recovery. This contrasts with the above case, which highlights the morbidity suffered due to late presentation. Screening of patients from endemic countries, especially those with a history of bathing in lakes and rivers and/or with eosinophilia on blood testing, would contribute to reducing the overall morbidity and mortality suffered by infected patients.

Renal transplant remains the only method of regaining renal function once significant damage to the kidneys has occurred as in the above case. A study following up victims of urinary schistosomiasis who underwent a renal transplant showed encouraging results. It suggested that there is no difference in rates of chronic or acute rejection in infected groups. However, it was noted that infected patients often required a higher dose of ciclosporin, with resultant increase in risk of ciclosporin-associated nephrotoxicity. There was also a higher rate of urinary tract infections in the infected group, despite no evidence of schistosomal reinfection.¹⁶

Learning points.

• In patients with a significant travel history, urinary schistosomiasis should be a differential diagnosis not only for haematuria, but also for obstructive uropathy and dysuria.

• Despite urinary schistosomiasis being an important disease in endemic countries, such late presentations are rare and lead to a poor prognosis for renal function.

• Despite failure in this case, prompt investigation, medical treatment and renal decompression are vital to improving renal function.

• Patients from endemic countries, especially those who exhibit high risk factors, should be screened for schistosomiasis to obtain an early diagnosis and significantly improve patient outcome.

Ethics statements

Patient consent for publication

Obtained.