Epizootic ulcerative syndrome (EUS), also known as mycotic granulomatosis (MG) or red spot disease (RSD), is a disease caused by the
water mould ''
Aphanomyces invadans''. It infects many freshwater and
brackish fish species in the
Asia-Pacific
Asia-Pacific (APAC) is the part of the world near the western Pacific Ocean. The Asia-Pacific region varies in area depending on context, but it generally includes East Asia, Russian Far East, South Asia, Southeast Asia, Australia and Pacific Isla ...
region and
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
. The disease is most commonly seen when there are low temperature and heavy rainfall in
tropical and
sub-tropical waters.
Clinical signs and diagnosis
At first, fish develop red spots on the skin. These lesions expand to form
ulcers and extensive
erosions filled with
necrotic tissue and
mycelium. This is followed by the development of
granuloma
A granuloma is an aggregation of macrophages that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. Such substances include infectious ...
s on the internal organs and death.
A provisional diagnosis can be made by using squash preparations of the skeletal muscle from beneath an ulcer to identify the septate hyphae of the water mould. Definitive diagnosis can be made based on
histopathogical findings and isolation of the pathogen.
Treatment and control
Infected fish should be moved into high quality water, where they may recover if their clinical signs are mild.
If disease occurs
eradication is required. Once the disease is eradicated, good
husbandry, surveillance and
biosecurity measures are necessary to prevent recurrence. In countries free of epizootic ulcerative syndrome,
quarantine and health certificates are necessary for the movement of all live fish to prevent the introduction of the disease.
References
*Epizootic Ulcerative Syndrome, reviewed and published by Wikivet at http://en.wikivet.net/Epizootic_Ulcerative_Syndrome, accessed 08/09/2011.
{{fish disease topics
Syndromes in fish