GLOSSARY 485 



IHN See Infectious Hematopoietic Necrosis. 



Immune Unsusceptible to a disease. 



Immunity Lack of susceptibility; resistance. An inherited or acquired 

 status. 



Immunization Process or procedure by which an individual is made 

 resistant to disease, specifically infectious disease. 



Imprinting The imposition of a behavior pattern in a young animal by 

 exposure to stimuli. 



Inbred Line A line produced by continued matings of brothers to sisters 

 and progeny to parents over several generations. 



Incidence The number of new cases of a particular disease occurring 

 within a specified period in a group of organisms. 



Incubation (Disease) Period of time between the exposure of an indivi- 

 dual to a pathogen and the appearance of the disease it causes. 



Incubation (Eggs) Period from fertilization of the egg until it hatches. 



Incubator Device for artificial rearing of fertilized fish eggs and newly 

 hatched fry. 



Indispensable Amino Acid See Essential Amino Acids. 



Inert Gases Those gases in the atmosphere that are inert or nearly 

 inert; nitrogen, argon, helium, xenon, krypton, and others. See Gas 

 Bubble Disease. 



Infection Contamination (external or internal) with a disease-causing 

 organism or material, whether or not overt disease results. 



Infection, Focal A well circumscribed or localized infection in or on a 

 host. 



Infection, Secondary Infection of a host that already is infected by a 

 different pathogen. 



Infection, Terminal An infection, often secondary, that leads to death 

 of the host. 



Infectious Catarrhal Enteritis See Infectious Pancreatic Necrosis. 



Infectious Disease A disease that can be transmitted between hosts. 



Infectious Hematopoietic Necrosis (IHN) A disease caused by infec- 

 tious hematopoietic viruses of the Rabdovirus group. Synonyms: Chi- 

 nook salmon virus disease, Oregon sockeye salmon virus, Sacramento 

 River chinook disease. 



Infectious Pancreatic Necrosis (IPN) A disease caused by an 

 infectious pancreatic necrosis virus that presently has not been placed 

 into a group. Synonym: infectious catarrhal enteritis. 



Inferior Mouth Mouth on the under side of the head, opening down- 

 ward. 



Inflammation The reaction of the tissues to injury; characterized clini- 

 cally by heat, swelling, redness, and pain. 



Ingest To eat or take into the body. 



