Description

Enteric Redmouth Disease (ERM) affects salmonids and other fish in both freshwater and seawater. It is caused by the gram negative bactrium Yersinia ruckeri that has been detected in 20 wild speciers of fish.

Symptoms

The disease can sometimes, but not always, exhibit bleeding from the mouth and mandibles. Fish can also exhibit loss of balance, lethargy, breathing difficulties and colour change as well as pop eyes, edema of the belly, bleeding of gills, skin and fins.

The disease can develop swiftly (acute) or more commonly slowly. Acute cases are indicated by high mortality with no external symptoms. When the disease develops more slowly then considerable or moderate mortality can occur over a few weeks before abating. Mortality rates increase with stress. Infections may reoccur regularly eveery few weeks if it is not eradicatedfrom an area.

Pathways

The main pathway is wild or farmed fish with a hidden (exibiting no signs) infection. The bacteria are excreted from infected fish and can survive of 2 months in freshwater and four months in the sea. There is also the possiblity it can be transmitted by birds. Other pathways include transmission by infected tools, boats and other equipment. Always sterilise equipment through approved disinfection regimes.