Hydatid cysts of zebra shark (Stegastoma fasciatum): A case report

Abstract

We report the hydatid cysts in a Zebra Shark (Stegastoma fasciatum) captured in the public aquarium of Thailand. The carcass demonstrated 0.5-3 cm diameter uniloculated cysts in the spleen, with thick capsules. The liver showed enlargement with yellowish brown color. Other organs were normal upon gross examination. Microscopically, the splenic cyst consisted of several hydatid cysts, infiltrated with numerous crystalline particles called hydatid sand. The inner surface of these cysts appeared to be producing necrotic cell like bodies which accumulated in the cyst. The spleen was infiltrated with numerous inflammatory cells mainly eosinophils. Furthermore, the liver was infiltrated with numerous hydatid sand and macrophages. The hydatid sand also spread in to the gastrointestinal tracts. From pathological findings, the shark was infected by hydatid pathogen. This is the first report of hydatid cysts in a shark.