Epizootic ulcerative syndrome (EUS) is a disease caused by the fungus

Fungus

A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

, Aphanomyces invadans

Aphanomyces invadans

Aphanomyces Invadans is a fungus which causes Red Spot disease, or Epizootic Ulcerative Syndrome in many species of fish....

. It infects many freshwater and brackish

Brackish water

Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...

 fish species in the Asia-Pacific

Asia-Pacific

Asia-Pacific or Asia Pacific is the part of the world in or near the Western Pacific Ocean...

 region and Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. The disease is most commonly seen when there are low temperature and heavy rainfall in tropical and sub-tropical waters. It may also be referred to as Mycotic Granulomatoses (MG) and Red Spot Disease (RSD).

Clinical Signs & Diagnosis

At first, fish develop red spots on the skin. These lesions expand to form ulcers

Ulcer

An ulcer is a sore on the skin or a mucous membrane, accompanied by the disintegration of tissue. Ulcers can result in complete loss of the epidermis and often portions of the dermis and even subcutaneous fat. Ulcers are most common on the skin of the lower extremities and in the gastrointestinal...

 and extensive erosions

Cutaneous conditions

There are many conditions of or affecting the human integumentary system—the organ system that comprises the entire surface of the body and includes skin, hair, nails, and related muscle and glands.- Diseases :...

 filled with necrotic tissue

Necrosis

Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...

 and mycelium

Mycelium

thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...

. This is followed by the development of granulomas

Granuloma

Granuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...

 on the internal organs and death.

A provisional diagnosis can be made by using a squash preparations of the skeletal muscle from beneath an ulcer to identify septate fungal hyphae. Definitive diagnosis can be made based on histopathogical findings

Histopathology

Histopathology refers to the microscopic examination of tissue in order to study the manifestations of disease...

 and fungal isolation.

Treatment & Control

Infected fish should be moved into high quality water, where they may recover if their clinical signs are mild.

If disease occurs eradication

Eradication of infectious diseases

Eradication is the reduction of an infectious disease's prevalence in the global host population to zero. It is sometimes confused with elimination, which describes either the reduction of an infectious disease's prevalence in a regional population to zero, or the reduction of the global prevalence...

 is required. Once the disease is eradicated good husbandry

Aquaculture

Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

, surveillance and biosecurity

Biosecurity

Biosecurity is a set of preventive measures designed to reduce the risk of transmission of infectious diseases, quarantined pests, invasive alien species, living modified organisms...

 measures are necessary to prevent recurrence. In countries free of Epizootic Ulcerative Syndrome, quarantine

Quarantine

Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....

and health certificates are necessary for the movement of all live fish to prevent the introduction of the disease.