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Vibrio Infections of Fish
Peggy A. Reed and Ruth Francis-Floyd  

Vibrio infections usually occur in fish from marine and estuarine environments, and have been reported throughout the world. Occasionally, vibriosis is reported in freshwater fish. The disease can cause significant mortality (=>50%) in fish culture facilities once an outbreak is in progress. Common names for Vibrio infections of fish include "red pest" of eels, "salt-water furunculosis", "red boil", and "pike pest". Vibrio infections can spread rapidly when fish are confined in heavily stocked, commercial systems and morbidity may reach 100% in affected facilities.

The disease is caused by gram negative bacteria in the family Vibrionaceae. This group of bacteria includes two important genera which can be significant fish pathogens. The genus Aeromonas includes several species which are important pathogens of freshwater fish, although they occasionally cause disease in marine species (see IFAS Extension Fact Sheet FA-14 for more information on Aeromonas infections of fish). Bacteria in the genus Vibrio are important pathogens of marine and brackish water fish, although they occasionally are reported in freshwater species. Seven species of Vibrio have been associated with disease in fish:
  • V. anguillarum (isolated most commonly from marine and brackish water fish);
  • V. ordalli (an atypical strain of
  • V. anguillarum , sometimes referred to as Biotype 2);
  • V. damsela (isolated from damsel fish);
  • V. carchariae (isolated from sharks);
  • V. vulnificus (reported in Japanese eels); and
  • V. alginolyticus (reported from cultured seabream in Israel).

A new, extremely pathogenic Vibrio infection of cold-water marine fish (i.e., salmon) is caused by V. salmonicida and is referred to as "cold-water vibrio" or "hitra" disease. Cold-water vibrio has not been reported in warm-water fish and will not be discussed further in this publication.

Vibrio species are also known to cause disease in humans, most often following the consumption of contaminated shellfish. Most serious illness is usually limited to individuals with a suppressed immune system, such as those with liver disease or Acquired Immune Deficiency Syndrome (AIDS). However, it is always wise to wear gloves while examining sick fish, and to wash your hands thoroughly with a bactericidal soap afterwards.


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