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Urinary schistosomiasis
  1. J F Paul,
  2. S Verma,
  3. K Berry
  1. Birmingham Children’s Hospital, Birmingham, UK
  1. Correspondence to:
 Dr S Verma, Birmingham Children’s Hospital, Steelhouse Lane, Birmingham, B4 6NH, UK

Abstract

Schistosomiasis, although the commonest cause of haematuria worldwide, often remains undiagnosed and is yet easily treated. An 8 year old boy with macroscopic, end stream haematuria is presented in whom the diagnosis was made only after some delay.

  • haematuria
  • schistosomiasis

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An 8.5 year old boy presented to his general practitioner with a five week history of macroscopic, end stream haematuria preceded by a vague history of mild trauma to the penis. Subsequent renal ultrasound, full blood count, clotting, renal function tests were all within normal limits. He was then seen by a paediatric nephrologist two months later. At that time his mother reported that she had closely monitored the episodes and found that the haematuria was always at the end of micturition, associated with mild dysuria, and lasted for several weeks at a time, with her son remaining well in between episodes. The haematuria was always preceded by febrile episodes lasting for four to five days with temperatures occasionally exceeding 39°C.

Of note, the family had spent a three month period visiting Africa one year prior to presentation but had not resided there previously. During that visit, the patient was entirely asymptomatic and the family had adhered to the regimen for malaria prophylaxis. The only relevant family history of note was that mother had had a renal biopsy in the past, for investigation of proteinuria, which showed minor focal sclerotic glomerulonephitis.

Clinical examination was unremarkable apart from port wine stains, one visible on his left forearm and the other on the left anterior chest wall. A plan was made to dipstick the urine for a three month period and then review in clinic.

The patient then represented to the accident and emergency (A&E) department two months later with a recurrence of the haematuria. At this stage his mother was concerned the patient was no longer gaining weight with loss of appetite. There was dysuria but no associated abdominal or loin pain. His mother incidentally mentioned that another child who was on the same African holiday had recently been diagnosed with schistosomiasis and that all the children had played in a stream together.

Clinical examination in A&E was unremarkable and subsequent urine microscopy was positive for schistosomiasis. The patient was given praziquantel and was reviewed again in the outpatient department a month later and reported no further episodes of haematuria.

DISCUSSION

Schistosomiasis is a chronic infection of the circulatory system caused by trematodes that inflame mainly the intestines, bladder, and liver. There are five types that affect humans.1S haematobium, which migrates to the perivesical and periureteral vessels, S mansoni to the inferior mesenteric, S japonicum to the superior mesenteric and the two others, S intercalatum and S mekangi to both mesenteric vessels. S haematobium is found mainly in Africa and the eastern Mediterranean region.

A person can become infected by prolonged contact (like bathing or swimming) with fresh water containing free swimming cercariae, the infective stage of the parasite that then enters the subcutaneous tissues, then the blood stream, migrates to the lungs, then to the liver, and finally to the mesenteric and perivesical venous plexuses. The parasite is excreted from the body via urine and faeces into fresh water and the miracidia eventually infects its intermediate hosts, the fresh water snails, where they develop into cercariae and the unfortunate cycle restarts again (fig 1).

Figure 1

Life cycle of schistosomes.

The main effect of the parasite is chronic granulomatous injury in response to the eggs that are shed. The first sign of infection can be a reactive dermatitis syndrome with pruritis, inflammation, and the presence of a small erythematous macule, at the site of entry of the cercariae in the first few minutes after invasion, which may disappear within a few hours. Up to two weeks later there maybe a small papule at the same site, also associated with pruritis. Approximately two months after infection the person can present with katayama fever, lasting for up to two weeks or several months, with temperatures reaching as high as 40°C with rigors, diarrhoea, lethargy, myalgia, headache, nausea, and vomiting.

Urinary schistosomiasis is caused by S haematobium and deposition of eggs in the bladder and ureters. The subsequent granulomatous inflammation causes nodules, polypoid lesions, and ulcerations in the lumens of the ureter and bladder, which in turn causes urinary frequency, dysuria, and end stream haematuria. Chronic renal failure and carcinoma of the bladder occur with increased frequency in S haematobium infected patients. When schistosomiasis affects the intestines, the patient can present with colicky abdominal pain, bloody diarrhoea, and hepatosplenomegaly. In the lungs the effects can be pulmonary hypertension and cor pulmonale. In rare cases it can infect the brain causing seizures.

DIAGNOSIS

The diagnosis strongly depends on the physician’s awareness of this as a possible differential diagnosis, especially if there is a history of bathing in fresh water in endemic areas of Asia, South Africa, and Africa, a history of a pruritic reaction on an exposed area of skin after bathing, or an unexplained febrile illness several weeks later. Urinary schistosomiasis is found mainly in patients between the ages of 10–30 years,2 with children 11–13 years having the highest incidence.3 The infection may recur in adults living in endemic areas as chronic reinfection produces incomplete immunity.

A definitive diagnosis can only be made with evidence of viable eggs in the urine, stool, or biopsy specimens. A urine sample best taken at midday after exercise, when most eggs are being shed, is ideal and microscopy often reveals eggs and parasites. In some cases a renal ultrasound, cystoscopy, and biopsy of the bladder mucosa is recommended if the urine microscopy is not conclusive or if the extent of infection and damage to the urinary tract needs further investigation. Identification of the schistosome eggs in stool with a thick smear method of Kato is very sensitive. Methods of immunoassay like ELISA and RIA are sensitive but not specific and can be considered in early schistosomiasis when there is a strong suspicion. In some cases the serological immunofluorescence antibody test for the presence of specific antibodies has been found to be a sensitive marker of acute and chronic infection.4 Evaluation of the eosinophil cationic protein in urine has been used as a sensitive method for detecting early urinary tract pathology.5 There has been some early work on the vaccine rSh28GST and results are encouraging.6 The treatment of urinary schistosomiasis is praziquantel, given orally as a single or divided dose of 40–60 mg/kg. General efforts to control schistosomiasis are focused on interruption of the life cycle at snail-human and human-snail transmission.

CONCLUSION

There is no doubt that if a high index of suspicion exists, early and prompt diagnosis and subsequent treatment is possible. A travel history is often beneficial in difficult diagnostic cases even when the presenting symptoms do not immediately suggest a tropical aetiology.

REFERENCES

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