무지개송어의 자어기에 Ichthyophonus sp.인 곰팡이가 감염되어 있는 것을 발견하고 그 후 계속 사육된 어군을 6개월마다 채집하여 병리조직학적으로 관찰하였다. 1. 무지개송어의 치어에는 Ichthyophonus sp.가 전신적으로 감염되어 있었으며, 2년생인 어류에는 Ichthyophonus sp.를 둘러싼 육아종이 많이 발생되고 있었다. 2. 각 조직내에 보이는 Ichthyophonus sp.는 다핵구상체가 가장 많았으며, 때로는 발아중인것과 계장체도 나타났다. 3. Ichthyophonus sp.의 cyst 주변에는 대단핵세포가 모인 번식성 염증를 볼 수 있었다.
Ichthyophonus disease broke out among rainbow trout (Salmon gairdneri) fry in November 1979, and after that a fish group containing diseased fish was kept for one year. The authors examined histopathologically the diseased fish 3 times, at 6 momths intervals. Diseased fish showed markedly stunted growth and darkish coloration, and anatomically the liver with small white nodules, the heart with red nodules, the spleen with granular nodules and the markedly tumefied kidney. Ichthyophonus invaded various tissues in the host and took the shape of multinucleate spherical or hyphal body. The multinucleate-spherical bodies contained many nuclei with a large nucleolus and granular cytoplasm. Histopathologically systemic dissemination and systemic proliferation by Ichthyophonus sp. wire indentified. In addition to a single multinucleate-spherical body appeared in the various tissue, large granulomas containing two to several generations of Ichthyophonus sp. were formed especially in the liver, kidey and spleen. The inflammatory response against Ichthyophonus was characterized by mononuclear-celluar proliferation with giant cell formation and fibrobasts proliferation.
