EPIZOOTIC ULCERATIVE SYNDROME - INFORMATION UP TO 1997

Epizootic ulcerative syndrome or EUS has been endemic in many countrie s in Asia and the Indo Pacific region since 1980. It has affected a wi de range of fish species. Infected fish reveal dermal ulcerative lesio ns throughout the body. The outbreaks occur at certain times of the ye ar, normally after flooding followed by cool weather. Typical clinical signs of the early stages of this disease are the petechial haemorrha gic lesions on the skin which later develop into deep ulcerative lesio ns throughout the body. Mycotic granulomas spread throughout the lesio ns and also into some of the internal organs. These histopathological observations are key characteristics in the identification and confirm ation of outbreaks of EUS. The epidemiology of this disease is still u ncertain, 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 b een reported. It seems clear from the epidemiological information, and research carried out, that EUS is infectious in nature. Parasites, ba cteria and viruses found in diseased fish are considered to be the sec ondary agents. Aphanomyces invadans, a pathogenic water borne fungus, most likely plays an important role in these disease outbreaks.