BiodiversityandDiseaseTransmission生物多样性和传播的疾病

,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Biodiversity and Disease Transmission,Stavros Calos,Agriculture,Lyme Disease and West Nile Virus,Mammalian and bird diversity leads to Lyme Disease and WNV in humans.,Higher biodiversity can reduce disease transmission,Case 1:A disease specializes on a single host species,and transmission is by direct contact.,dS/dt=(b m)S SI+(+b)I,dI/dt=SI (+m)I,Densities of susceptible(S)and infected(I)hosts,b,b,m,and m are birth and deaths for susceptible and infected host,the rate of encounter of between infected hosts and susceptible ones()times the probability of transmission().,-Recovery rate,dS/dt=(b m)S SI+(+b)I,dI/dt=SI (+m)I,Case 1 Assumptions:,Host is regulated solely by pathogen.,All recovered individuals can be,reinfected,.,Disease only transmissible within one species.,Abundances of susceptible(S)and infected(I)hosts,b,b,m,and m are birth and deaths for susceptible and infected host,Recovery rate(),the rate of encounter of between infected hosts and susceptible ones()times the probability of transmission().,Biodiversity and Case 1:,dI/dt=SI (+m)I,Reduce rate of encounter()by adding species,Reduce probability of encounter leading to transmission()by adding species,Increase death rate of infected individuals(m)by adding species,Case 2:A disease specializes on a single host species,and vectors transmit the disease.,dI/dt=SZ (+m)I,Densities of uninfected(W)and infected(Z)vectors,=Vector recruitment rate,=vector death rate,the rate of encounter()times by the probability of transmission().,dW/dt=W-IW,dZ/dt=IW Z,Biodiversity with a Vector Species:,dW/dt=W-IW,dZ/dt=IW Z,dI/dt=SZ (+m)I,Encounter Reduction,Reduce dI/dt by increasing m,Reducing rate of encounter between infected vectors()and susceptible hosts.,The Dilution Effect!,Added species are still preyed upon by vector,but they are not as capable of carrying the disease and transmitting it to the vector.,Reservoir Hosts,Vector Species,Incidental Host,Reservoir Hosts,Vector Species,Incidental Host,Questions?,