U.S. Fish & Wildlife Service Overview of infection and disease problems in the Klamath River basin. J.Scott Foott CA-NV Fish Health Center The findings and conclusions in this presentation have not been formally disseminated by the USFWS and should not be construed to represent any agency determination or policy.
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U.S. Fish & Wildlife Service Overview of infection and disease problems in the Klamath River basin. J.Scott Foott CA-NV Fish Health Center The findings.
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U.S. Fish & Wildlife Service
Overview of infection and disease problems in the Klamath River
basin.
J.Scott Foott
CA-NV Fish Health Center
The findings and conclusions in this presentation have not been formally disseminated by the USFWS and should not be construed to represent any agency determination or policy.
concepts• Infection is not equivalent to disease
– Infection = parasite can establish & replicate itself within host (all fish have parasites)
– Disease = deviation / interruption in normal function
• Many protozoans, helminths, commensal bacteria, (virus ?? Rare) are present in KR fish. Meeting focus on Cs & Pm
usfws
Please ask these questions of all data presented today
“It takes 3 to tango”
• I host
environmentParasite (pathogen)
Disease
Replication & temperature
Stress, immune function, and temperatureVirulence of
pathogen(s)
Synergism of multiple infections
Infectious load (challenge)
• Severity of Ceratomyxosis in Klamath River suggests a shift in the host: parasite balance towards C.shasta– Chronic exposure to high levels of
actinospores overwhelm resistance– Biological question = model probability of
infection and disease with duration of rearing in KR
Prognosis of infection
Invasion by pathogen
None/unsuccessfulDamages self
Contain / destroypathogen
Disease / deathCarrier state
Disease / deathpredation
Disease / recovery
Host response(s)
Transmission
• Contact- attach&invade- multiple in host
• Congregation of juveniles and adults in thermal refugia enhance transmission of some bacteria and parasites– Fc and ICH (not Cs & Pm)
• Evidence of progressive disease leading to mortality in KR salmon under summer temperature conditions– 2002 3d exposure = >80% mortality 17d– 2006 studies
Incidence of C.shasta & P.minibicornis infection in juvenile chinook in the Klamath R. & estuary, May – July (histology)
0102030405060708090
100
CS PM
Cs (KR) = 35 – 50% << Pm (KR) = 47 -92%
Cs drop in KE, different fish (TR influence)
External bacterial and parasitic infectionsFlavobacterium columnare and Ich
• Fc = 3 – 57% POI– > 20C temperatures– disease problem of
adult salmon (02 event)
• Problem in all live box exposure studies in KR
• Ich = both adult and juvenile fish
IMPACT ?
• 70 – 90% mortality estimates for Chinook fry & smolt stage due primarily to predation – MC Healey (Chinook Chapter – Pacific Salmon life histories eds
Groot & Margolis)
• Additional influence of > 35% dual parasite infection on the 10- 30% “normal” survival rate?– Need for in-river survival studies in KR
Appreciation
• Strong commitment and high level of cooperation for Fish Health work by Klamath fisheries community