Chapter 50 - Epizootic ulcerative syndrome

Abstract

Epizootic ulcerative syndrome (EUS) is a global fungal fish disease of concern, affecting at least 94 species of finfish from farms and wild populations in freshwater and estuarine environments. It was first reported in 1971 in Japan and is variously termed red spot disease, mycotic granulomatosis, ulcerative mycosis, and more recently epizootic granulomatous aphanomycosis. EUS has resulted in heavy economic losses particularly for small-scale, mixed species fisheries and aquaculture farms in the Asian-Pacific region with estimates of USD20,000 to 100 million (cumulatively about USD114 million) across countries including Sri Lanka, Nepal, India, Pakistan, Bangladesh, Thailand, Indonesia, and Australia during the period 1980–1996. EUS is caused by Aphanomyces invadans, a fungus belonging to Saprolegniales, Oomycetida, and is classified in Stramenopiles or Chromista along with diatoms and brown algae. Disinfection of infected fish pond by hydrated lime and addition of salt to inhibit the fungus has been used in EUS outbreaks. For cultured species, use of resistant Nile tilapia, milk fish and Chinese carp in endemic regions of EUS is an option. Movements of ornamental fishes are a potential pathway for the spread of EUS, and control of this movement is required.