1. Dynamic Consequences of Species Interactions in A Dynamic Parasite Model CSS Workshop Presentation 2005 Joanne Lello, Susan McClure (CSIRO LI) Andrew Fenton (University of Liverpool, UK) & Mark Viney (University of Bristol, UK) CSS Workshop Presentation 2005 Joanne Lello, Susan McClure (CSIRO LI) Andrew Fenton (University of Liverpool, UK) & Mark Viney (University of Bristol, UK)

2. Taking A Community Ecology Approach to Pathogen Infections

3. Why Take A Community Approach? Because interactions can: –alter pathogen dynamics –alter disease transmission rates –increase disease severity –reduce control efficacy

4. What comprises the community? – The Host acting as an environment – The Host Immune System acting as a player – Other pathogens What kind of a system is it? –Predator Prey –Competitors and mutalists –War

5. Modelling the system P1P1 P2P2 H2H2 P1P1 P2P2 H1H1 ……… P1P1 P2P2 HnHn Mature Larval Pool (L 1 ) Mature Larval Pool (L2) Immature Larval Pool (I 1 ) Immature Larval Pool (I2)

6. Establish as Immature P 1 Establish as Mature P 1 Adult Survival Reproduction Establish as Immature P 2 Establish as Mature P 2 Adult Survival Reproduction The Model INTRA-Specific Density Dependent Effects

7. Establish as Immature P 1 Establish as Mature P 1 Adult Survival Reproduction Establish as Immature P 2 Establish as Mature P 2 Adult Survival Reproduction INTER-Specific Density Dependent Effects The Model

8. Model outputs Effects on larval establishment Time series Species 2 Species 1 Adult worm numbersFaecal Egg Output Species 2 Species 1 Species 2 Species 1 Time Parasite No.s

9. Adult worm numbers Time series Faecal Egg Output Species 2 Species 1 Species 2 Species 1 Time Parasite No.s Species 2 Species 1 Effects on Fecundity

10. Faecal Egg Output Species 2 Species 1P2 adults P2 egg output Effects on Fecundity Explained

11. Faecal Egg Output Species 2 Species 1 P1 adults P1 egg output Effects on Fecundity Explained

12. Faecal Egg Output Species 2 Species 1 P2 adults P1 egg output Effects on Fecundity Explained

13. Adult wormsEggs Effects on Fecundity Explained

14. What the model suggests NOT all interaction leads to structure Negative correlation does NOT equal interaction Host behaviour and biology can make alter outcome Immune memory can alter relationships

15. What next? Let the worms into the model IN FOCUS –The H. contortus - T. colubriformis relationship –H. contortus immunosuppression HAVE A PREDICTION CAPABLE MODEL!!!

16. Thanks to: Kerri Tyrrell Troy Kalinowski Mandy Choice Brian Cross Callum Mack Kerri Tyrrell Troy Kalinowski Mandy Choice Brian Cross Callum Mack

17. Adding some reality Trichostrongylus vitrinus Trichostrongylus colubriformis Haemonchus contortus Ostertagia circumcincta Abomasum Small Intestine ? -ve on fecundity Negative effect on adult worm numbers

18. The Players Host immunityThe pathogens

19. The Players Host immunityThe pathogens

20. The Players Host immunityPathogens bacteria virus Helminths

21. The Sheep Helminth Community Four Key Parasites –Abomasum Haemonchus contortus (Hc) Ostertagia circumcincta (Oc) –Small Intestine Trichostrongylus colubriformis (Tc) Trichostrongylus vitrinus (Tv)