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.

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

“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)

synergism

• Cs (enteritis) + Pm (glomerulonephritis) + external infections (ion loss)

• 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

• Meeting organizers