Flavobacterium psychrophilum, cause of ... - cop.eXtension.org

infected, and geographic origins that have proven to be epidemiologically valuable at a
local or regional scale (Cipriano et al. 1996; Chakroun et al. 1998; Madsen and
Dalsgaard 2000).
Mixed infections of certain viral, bacterial or parasitic fish pathogens and F.
psychrophilum are frequently observed in various salmonid fish species. Concurrent
infections of rainbow trout with F. psychrophilum and Infectious Pancreatic Necrosis
virus have been described by Evensen and Lorenzen (1997). In the Pacific Northwest this
bacterium is often found in rainbow and steelhead trout in a dual infection with infectious
hematopoietic necrosis virus (IHNV; La Frentz et al. 2004). An epizootic of IHNV,
BCWD and external fungi was observed during several winters in two and three year old
kokanee salmon (O. nerka) in a central Oregon reservoir (Engelking and Kaufman 1994).
Mixed infections of F. psychrophilum, external fungi and the virus causing erythrocytic
inclusion body syndrome (EIBS) occur in yearling coho and Chinook salmon during the
fall and winter months (Leek, 1981; Piacentini et al. 1989). In fact, the detection of
BCWD infections in yearling coho or Chinook salmon in the fall or winter should alert
the fish health specialist to also test these fish for EIBS virus. Also, BCWD has been
found in association with furunculosis among coho salmon (Cipriano et al. 1996) and
with coho and Chinook salmon with bacterial kidney disease. Hansen (1990) has also
noted that Fry Mortality Syndrome (syn. – RTFS) has occurred in conjunction with high
prevalence of intestinal infestation of rainbow trout by Hexamita salmonis and
ectoparasitism by Costia necatrix (Ichthyobodo). Mortality associated with F.