Infectious Hematopoietic Necrosis

Agricultural Disaster Preparedness and Recovery November 04, 2011 Print Friendly and PDF

Infectious Hematopoietic Necrosis is a highly contagious viral disease of fish, especially rainbow and steelhead trout and Atlantic and Pacific salmon. The disease is spread through contaminated water, feed, or direct fish-to-fish contact where the virus enters through the mouth or gills. The mortality rate of Infectious Hematopoietic Necrosis is high in fry and juvenile fish.

Endemic Areas

The United States, Europe and Japan.


Clinical Signs

  • Distended abdomen
  • Bulging eyes
  • Darkening body color
  • Long fecal casts trail from anus
  • Sluggish movement



There is no specific treatment for Infectious Hematopoietic Necrosis. Any fish suspected of having this disease should be reported to the State Veterinarians or USDA Area Veterinarian in Charge immediately.



Outbreaks of Infectious Hematopoietic Necrosis may be prevented by raising the water temperature and developing sound biosecurity practices.


Public Health

Infectious Hematopoietic Necrosis is not a public health threat.



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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.