# Presentation: 834100

##  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.

## Incidence of parasite infection in adults (histology)

|  |  C.shasta | P.minibicornis |
| --- | --- | --- |
| IGH
FCS      2005
FCS      2006
STT      2005 | 
16 / 20 (80)
pending JAN07
9 / 10 (90) c | 
18 / 20 (90) ab
20 / 20 (100) ab
4 / 10 (40) ab |
| TRH
FCS      2005
STT      2005
COHO  2005 | 
1 / 19 (5)
19 / 20 (95) c 
16 / 20 (80) d  | 
19 / 19 (100)
16 / 20 (80) ab
3 / 20 (15) ab |
| Feather R 
FCS      2005
STT      2005 | 
9 / 20 (45) d
10 / 20 (50)  | 
5 / 20 (25) a
0 / 20 (0) |
| CNFH
FCS      2003
STT      2003 | 
28 / 60 (47)
3 / 30 (10) | 
38 / 60 (60)
nd |

## Incidence of parasite infection in adults (histology)

- Steelhead Cs = not invasive

## 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

***Disease***

- Replication & temperature

- Stress, immune function, and temperature

- Virulence 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

***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)

- Cs (KR) = 35 – 50%   **<< **    Pm (KR) = 47 -92%

- Cs drop in KE, different fish (TR influence)

## External bacterial and parasitic infectionsFlavobacterium 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