What is epizootic ulcerative syndrome (EUS)?
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pizootic ulcerative syndrome or EUS is the name given to a disease caused by an infection with the oomycete fungus known as Aphanomyces invadans or A. piscicida. Aphanomyces is a member of a group of organisms commonly known as water moulds; they are currently recognized asbbelonging, with diatoms and brown algae, to the group of Stramenopiles (OIE, 2019).This group of organisms contains a number of pathogens of plants and animals that have had devastating effects on agriculture and aquaculture throughout the world. In contrast to free-living saprophytic water moulds, Aphanomyces invadans is an obligate pathogen.
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EUS is an epizootic condition affecting wild and farmed freshwater and estuarine finfish since it was first reported in 1971. In affected areas, the disease often occurs seasonally and may be worse in some years.
©FAO/B. Van der Waal, Namibia
EUS is also known by other names such as red spot disease (RSD), mycotic granulomatosis (MG), ulcerative mycosis (UM) and in 2005 it was suggested to rename EUS as epizootic granulomatous aphanomycosis (EGA) (Baldock et al. 2005). However the name EUS is most frequently used to describe the disease.
Figure 1. Enteromius paludinosus – Straightfin barb showing typical epizootic ulcerative syndrome (EUS) lesion. Caprivi Region, Namibia, 2007.
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