WFSC 403 1st Edition Lecture 20 Outline of Last Lecture I Basic Concepts a Review b One Health prudent predator Virulence RQ SEIR i Rabies fig 13 14 page 246 II Math Models of host disease a General model i Fig 13 1 p 236 b SIR closed population c SI open population d R0 working with data i Page 237 e Disease control vaccines cull i Page 238 Outline of Current Lecture I Basic Concepts a Review II Math Models a Review III Effects of disease on individuals IV Effects of disease on populations a Threshold b Vaccination vs Cull c virulence d Cryptic Cycle V Evolution of host parasite systems a Virulence vs Transmissibility b Hot to maximize R0 c Does disease affect populations d Under what conditions does an epidemic occur Current Lecture Some diseases you develop immunity for life so you do not become susceptible again o is the recovery rate These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Everything is constant except S I R Assume constant population size and constant transmission rate o Number of infected is increasing o Go from right to lef More individuals bumping into each other more contact rate o Is this disease really going to effect at the populations And will an epidemic form o It will effect additive mortality populations o Could there be an epidemic without there being an effect on population size Yes that is possible Can run through a population Why do we care o If in I phase can pass it on to other populations Under what conditions is there an epidemic o R0 is greater then 1 Equivalent to net reproductive rate intrinsic rate of increase of pathogen Transmission rate recovery rate means going to infect other individuals Lizards example in book o Lower reproductive output of lizards Book documents death of seals and crows but it is hard to know if they would have died anyways without disease If this was additive or compensatory o Harbor seals o Crows Cumulative death count o Number who died today Threshold o Bison Brucellosis o o Brucellosis causes abortion o Zero prevalence in males and females Goes up with age due to exposure Develop antibodies to pathogen Able to collect just get a blood sample Sample only says pathogen was there doesn t mean that the animal was infected What makes disease fizzile out Contact rate Fewer susceptible in population longevity of disease recover immune before bump into someone Vaccine vs Cull o Rabies virulence o Myxomatosis in Rabbits Cryptic Cycle o Tuberculosis in possums From a human point of view the pathogen is cycling in cryptic sort of way We only care about it when it jumps to a host we do care about
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