Renal stephanuriasis: Gross and microscopic findings in naturally-infected pigs from St. Kitts, West Indies

Abstract

Stephanurus dentatus, the kidney worm of swine, is an important nematode parasite in outdoor swine populations worldwide. Infection is most common in tropical and subtropical areas and results in decreased weight gain and condemnation of edible parts invaded by migrating larvae. Worms reach sexual maturity within nodules at the peri-ureteral fat which communicate with the ureter and eggs are eliminated in the urine. At the St.Kitts abattoir, the kidneys of 10 pigs with gross lesions of stephanuriasis were examined microscopically. Parasitic tracts surrounded by areas of hemorrhage and inflammation were present in the fibro-adipose tissue around the ureters, renal pelvis and, rarely, within the renal parenchyma. Morulated eggs were found within nodules containing encysted worms. Due to the lengthy development of the parasite within the definite host, the finding of patent stephanuriasis in slaughterhouse pigs is unusual and likely the result of poor local management practices which lead to reduced weight gains, delays in the attainment of market weight and the frequent slaughtering of one year old pigs.