Studies on Schistosomiasis. 9. Pathology of the bovine urinary tract

Abstract

Pathological findings in the urinary tract of 40 head of cattle, experimentally or naturally infested with Schistosoma mattheei, are presented. Lesions of the ureter found in 57,5% of the cases consisted of linear granulomata with associated haemorrhages or granular patches. The segmental hydro-ureter caused by disruption of the muscular tunic by a granular patch type of lesion was a prominent finding. Bilharzial bladder lesions observed in 75% of the animals were of 4 distinct types: granulomatous foci 1-2 mm in diameter, granular patches, polypoid patches and polyps. In all cases with bladder lesions the fundus was affected; neck and trigonal lesions tended to occur in the more severely affected bladders. The Hoeppli phenomenon was more common than in other species and was associated with the subacute stage of lesion. Urinary bladders with ovum granulomata: throughout the lamina had more severe microscopic lesions than those with ovum granulomata in the submucosa only. The stage of development of the bladder lesion was related directly to the length of infestation of the animal. There was an inverse ratio between the percentage of live ova in the bladders and increased chronicity of the lesions. Since the effects of reinfestation on the pathology were quantitative, a larger percentage of the reinfested animals had bladder and ureteric lesions, which tended to be more severe and, in the bladder, more chronic than in singly infested animals. A significant rank correlation was observed between the W-D index (relating the worm burdens and the duration of infestation) and the severity of macroscopic and microscopic bladder lesions (P< 0,001). The duration of infestation and the W-D index were significantly greater in animals with bladder lesions than in those without (P< 0,000 1) and no lesions of the bladders and ureters were found in animals infested less than 185 days, indicating an extended prepatent period in bovine urinary schistosomiasis. On the other hand, there were no significant differences between the worm burdens of animals with or without bladder lesions, suggesting that the first lesions appear between 70 and 185 days after infestation, regardless of the number of worms present. Possible migration routes to the urinary tract are discussed. The bilharzial granulomata observed in the renal pelvis of 20% of the animals is the first reported incidence of bilharzial lesions of the renal pelvis. The incidence of renal parenchymal lesions in infested animals was more than double that in uninfested controls.