Redmouth Disease

Abstract

Redmouth disease is caused by the infection of the enteric bacterium Yersinia ruckeri. ​The disease was first noticed in rainbow trout Oncorhynchus mykiss in the USA in 1950s and has since been observed in salmonids and some other fishes in many countries. ​Y. ruckeri can be classified into different biotypes, serotypes, or genotypes, according to biological properties such as motility or enzyme activity, antigenicity, or gene sequences. ​In particular, O-antigen, which is one of the markers for serotyping, is an important antigen for the vaccination for of Y. ruckeri. ​In Japan, redmouth disease is listed as one of the notifiable diseases of aquatic animals by the government to prevent occurrences or spreading of the disease. ​This review describes topics necessary important for the diagnosis and control of the disease.