Why testes are resistant to hydatidosis: Is blood-testis-barrier responsible for this resistance?

Abstract

There have been reports of hydatid disease occurring in most of the vital organs such as the lungs, liver, and brain, while only 2-3% of all such cases have affected the urinary tract, with the testes being an extremely rare anatomic site for echinococcosis.
Testes are extremely rare sites for echinococcosis. To our knowledge only three cases of testicular hydatid disease have been reported so far. In this laboratory animal model, we studied hydatidosis in rabbit testis. Fourteen male albino rabbits (body weight 2.5-3 kg) were randomized into two groups: Group A (study group), for testicular injection and Group B (controlled group), for intraperitoneal injection of viable protoscoleces. We directly infected the right testis of seven rabbits (Group A) with infective viable protoscoleces that were obtained from hydatid cyst of cow's liver, and we injected intraperitoneally the
same fluid to another male rabbits (Group B) for control, Then, housed them under pathogen-free conditions for a ten-week period (70 days). One rabbit from Group A and three from Group B died one day after injection while the other survived during
the follow-up period. At the 10th week, they were all anaesthetized with IM injection of ketamine hydrochloride (l00 mg/kg) and xylazin [Rumpon] (l0 mg/kg) and then all testes were studied with ultrasonography. In Group A, all testes were excised, and in
Group B, we removed the liver, kidneys and took four biopsies from peritoneum, for histopathologic investigation. There was demonstrable hydatid cyst (protoscoleces and germinative layer) in testes of five rabbits from Group A, but in one rabbit, both
testes were normal. In Group B, three out of four rabbits developed peritoneal hydatidosis. The mechanism of testicular resistance to echinococcosis could be due to blood-testis barrier because when we directly infected the testes of rabbits with protoscoleces, hydatid cyst developed.

Keywords: hydatid disease, hydatidosis, testis, blood-testis-barrier, rabbit, echinoccocosis.

Nigerian Journal of Parasitology Vol. 29 (2) 2008: pp. 84-87