Prevalence and histopathology of Echinocephalus sinensis (Nematoda: Gnathostomatidae) in natural and experimental hosts

Abstract

Examination of 240 oysters (Crassostrea gigas Thunberg) cultured in Hong Kong showed that 31% of the animals were infected with the larvae of Echinocephalus sinensis Ko, 1975. The worms were located in the genital ducts or Leydig tissue. The prevalence of infection appeared to increase with age. Fibroplasia, and infiltration of amoebocytes were commonly observed at the infected sites.Eleven of 15 eagle rays (Aetabatus flagellum) were found to be infected with adult E. sinensis. Worms were located in the intestine, either in nodules or attached directly to the intestinal wall. Infiltration of leucocytes and fibrinous exudation were commonly seen at the infected sites.Worms were found partially embedded in the stomach and the small and large intestine of a cat and a rhesus monkey experimentally infected with larval E. sinensis from oysters and examined 19 and 17 h post infection. Some worms had penetrated as far as the muscularis externa. Intensive cellular infiltrations were seen at the infected sites.