Schistosomiasis--an unusual cause of ureteral obstruction: a case history and perspective

Abstract

A male, 32 years of age, presented with dysuria and abdominal pain, but no gross hematuria. He emigrated three years earlier from Somalia, East Africa, and was currently employed as a poultry processor in a rural Wisconsin community. The patient denied any trauma, sexual activity, or family history of significant illness. Abdominal and genitourinary exams were normal with negative tests for gonococcus and chlamydia. Urinalysis demonstrated microhematuria. A urogram and retrograde pyelogram revealed a mildly dilated right ureter down to the ureterovesical junction. Cystoscopy showed punctate white lesions on the bladder urothelium. Ureteroscopy was used to biopsy abnormal tissue in the distal ureter and bladder. Biopsy tissue demonstrated deposits of Schistosoma haematobium eggs. No ova were seen in collected urine specimens. The patient was successfully treated with praziquantel and will be monitored for sequelae of the disease. Schistosomiasis (Bilharziasis) can be expected to be seen with increasing frequency in the United States with the continuing influx of immigrants and refugees, as well as the return of travelers and soldiers from endemic areas. While no intermediate snail host exists for the transmission of Schistosoma sp. in the United States, the continued importation of exotic animals including snails from Africa, as well as the ability of schistosomes to shift host species warrants concern. Additionally, increasing disease associated with non-human bird schistosomes of the same genus seen in the midwestern United States is occurring throughout Europe. One should be aware that praziquantel may not always be available or effective in the treatment of schistosomiasis. It behooves the practicing clinician to remain updated on the status of this widespread zoonosis.

Figure 1

An intravenous urogram displays a mildly dilated right ureter (arrow) down to the ureterovesical junction.

Figure 2

Retrograde pyelogram demonstrating irregularity in the distal 2 cm of the right ureter.

Figure 3

Histopathology of the abnormal urinary tract tissue obtained on ureteroscopy reveals Schistosoma haematobium eggs with their characteristic terminal spine (arrow).

Figure 4

Eggs are eliminated with feces or urine 1. Under optimal conditions the eggs hatch and release miracidia 2, which swim and penetrate specific snail intermediate hosts 3. The stages in the snail include 2 generations of sporocysts 4 and the production of cercariae 5. Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host 6, and shed their forked tail, becoming schistosomulae 7. The schistosomulae migrate through several tissues and stages to their residence in the veins (8, 9). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species 10. For instance, S. japonicum is more frequently found in the superior mesenteric veins draining the small intestine A, and S. mansoni occurs more often in the superior mesenteric veins draining the large intestine B. However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. S. haematobium most often occurs in the venous plexus of bladder C, but it can also be found in the rectal venules. The females (size 7 to 20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S. mansoni and S. japonicum) and of the bladder and ureters (S. haematobium), and are eliminated with feces or urine, respectively 1. Pathology of S. mansoni and S. japonicum schistosomiasis includes: Katayama fever, hepatic perisinusoidal egg granulomas, Symmers' pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in the brain or spinal cord. Pathology of S. haematobium schistosomiasis includes: hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S. japonicum, and dogs for S. mekongi. Geographic Distribution: Schistosoma mansoni is found in parts of South America and the Caribbean, Africa, and the Middle East; S. haematobium in Africa and the Middle East; and S. japonicum in the Far East. Schistosoma mekongi and S. intercalatum are found focally in Southeast Asia and central West Africa, respectively. (Figure provided by Alexander J. da Silva and Melanie Moser for copyright-free dissemination through the Public Health Image Library of the Centers for Disease Control and Prevention. Legend obtained through the Division of Parasitic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention.)