Pathological Study on Streptococcicoses

Histopathology of Infected Fishes

Abstract

The present author histopathologically studied on various Streptococcicoses : 1) infections with a-hemolytic bacteria in sea-cultured yellowtail (Seriola quinqueradiata), striped beakperch (Oplegnathus fasciatus), Japanese horse mackerel (Trachurus japonica) and striped jack (Caranx delicatissimus), 2) infections with β-hemolytic bacteria in sea-cultured Japanese flounder (Paralichthys olivaceus), ayu (Plecoglossus altivelis) and rainbow trout (Salmo gairdneri) which were reared in fresh-water ponds. The bacteria frequently infected eyes of fishes.
Histopathologically α-hemolytic bacteria usually caused granulomatous inflammation at infected lesions of yellowtail, striped beakperch, Japanese horse mackerel and striped jack. β-hemolytic bacteria caused systemic infection with septicemia in ayu and rainbow trout, and extensive suppurative inflammation in eyes of Japanese flounder.