Davies, T.J.

Smallegange, I.

Toorians, M.E.M.

CGSpace

1: Bovine tuberculosis (bTB) spills over into many wildlife mammal species4: Multi-host model shows importance of community structure3: Definitions of community-structure metrics and multi-host model2: Including community structure into multi-host disease modelHost community structure determines pathogen outbreak potentialMarjolein EM Toorians1, Isabel Smallegange2 and T. Jonathan Davies1,31: Department of Botany, University of British Columbia, Canada2: Institute for Ecosystem and Biodiversity Dynamics, University of Amsterdam, Netherlands3: African Centre for DNA Barcoding, University of Johannesburg, South AfricaMarjolein.Toorians@botany.ubc.ca• Buffalo (Syncerus caffer) are bTBmaintenance hosts. • Transmission can be:• Direct (herds)• Indirect (environment)• Waterholes are high risk for transmission.Transmission = contact rate x probability of successful transmissionThis model will help to identify the hosts that contribute highest to the transmission of the disease and how the structure of the community can explain these spillover and –back events, helping policy makers in finding the right pathways to focus time and resources towards.Dilution effect: High diverse communities have lower disease risk1. Therefore, define community diversity with phylogeny2, e.g.:Model includes pathogen competence for each species pair, e.g.:Structure of community can now predict disease outbreak potential (R0)References: 1: Ostfeld & Keesing (2000). Cons. biol 14: 722-728; 2: Parker et al. (2015) Nature 520.7548 : 542-544; 3: Srivastava et al. (2012) Ecol. let. 15: 637-648; 4: Cadotte & Davies (2016) Princeton University Press.- Phylogenetic Diversity (PD)3:Sum of branch lengths𝑃𝐷 =  𝜆- Mean Pairwise Distance (MPD)4:Mean distances of pairwise combinations𝑀𝑃𝐷 =  1𝑁𝑑- Variance (varPPd)4:Mean variance of distances: 𝑉𝑎𝑟𝑃𝑃𝑑 = 𝑚𝑒𝑎𝑛(𝑣𝑎𝑟( 𝑑 ))• R0 determined by diversity of the community (PD) and the structure of the tree (imbalance). • Underlying dynamics of community are of importance when assessing diseases in multi-host systems!Tree imbalance:R0: Multi-host model predicts outbreak potential & relative importance of each host:Max eigenvalue matrix R = R05: Proposed application and One Health relevanceUsing eDNA for environmental (indirect) transmission of bTB from waterholes Camera traps to find direct contact rates at waterholesBalanced vs.     UnbalancedBiodiversity metrics:Phylogenetic distance: dEDλFig credit:Sylvia HerediazUBC Zoology

Host community structure determines pathogen outbreak potential

https://cgspace.cgiar.org/bitstream/10568/116689/1/marjolein_toorians.pdf

Host community structure determines pathogen outbreak potential

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