Epizootic Ulcerative Syndrome: Information up to 1997.

Abstract

Epizootic ulcerative syndrome or EUS has been endemic in many countries in Asia and the Indo Pacific region since 1980. It has affected a wide range of fish species. Infected fish reveal dermal ulcerative lesions throughout the body. The outbreaks occur at certain times of the year, normally after flooding followed by cool weather. Typical clinical signs of the early stages of this disease are the petechial haemorrhagic lesions on the skin which later develop into deep ulcerative lesions throughout the body. Mycotic granulomas spread throughout the lesions and also into some of the internal organs. These histopathological observations are key characteristics in the identification and confirmation of outbreaks of EUS. The epidemiology of this disease is still uncertain, however, a similar disease called mycotic granulomatosis was reported in Japan in 1971. In the following year red spot disease was reported in estuarine fish from Queensland, Australia. Since then the disease has spread to almost all countries in Southeast Asia and the Indian subcontinent. Recently (1996) an EUS outbreak in Pakistan has been reported. It seems clear from the epidemiological information, and research carried out, that EUS is infectious in nature. Parasites, bacteria and viruses found in diseased fish are considered to be the secondary agents. Aphanomyces invadans, a pathogenic water borne fungus, most likely plays an important role in these disease outbreaks.