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EarthWord: Infectious Haematopoietic Necrosis (IHN)

October 26, 2015

Infectious haematopoietic necrosis (IHN) is an infectious viral disease of salmon and trout.

EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

Image: A Rainbow Trout Rests Among Substrate in Panther Creek
A rainbow trout rests among substrate in Panther Creek upstream of Big Deer Creek, central Idaho. Panther Creek was severely damaged by heavy metals released from mining and milling activities at the former Blackbird Mine. USGS and other scientists compiled a 30-year record of recovery of the stream’s fish and macroinvertebrate populations.


  • Infectious haematopoietic necrosis (IHN) is an infectious viral disease of salmon and trout.

Use/Significance in the Earth Science Community:

  • IHN was first recognized in the 1950s in sockeye and Chinook salmon. The disease has the most economic significance for freshwater farms, however Pacific and Atlantic salmon (Salmo salar L.) in both fresh and seawater have been severely affected.
  • Researchers at the WFRC are creating a set of molecular tools by cloning each of the viral genes and sequencing the entire genome. This information is stored in an IHN database. When an IHN virus epidemic occurs, our researchers use molecular genetic methods to characterize the specific virus type, and compare it with other known IHNV types in our database. Similar methods are used for other fish viruses and for epidemics of flu, SARS, and anthrax.


Next EarthWord: Is your water acting up? Talking back maybe? There’s a word for water like that…

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