Question

There are two notable reasons that pathogens have the "upper hand" in driving pathogen-host co-evolution. What are they? (Answers should be less than 5 words!) A model developed for chronic wasting disease in deer in Alberta estimated RO value to be 4.0 in some situations (Potapov 2015). Suppose there is a vaccine available for chronic wasting disease (there isn't, unfortunately). What is the critical vaccination threshold (Vcrit) for this disease? How would you interpret your result from part a? True or False: A disease with a higher Ro is more virulent than a disease with a lower RO. (If you wish, you can explain your answer). Explain at least 2 pros and 2 cons of vaccinating wildlife for an infectious disease. What is the role lizards play in Lyme disease in California? Explain how this may change the disease ecology of the Lyme disease pathogen?

Answer 1

i) The gene-for-gene (GFG) model
ii) The matching-alleles (MA) model
First we will calculate the critical immunization threshold
qc = 1 − 1/R0  
= 1-1/4 = 0.75 (meaning 75% may have disease)
vaccine coverage or Vcrit, Vc =qc/E, E is vaccine efficiency let us imagine it should be 100% or 1
then Vcrit, Vc =qc/E,
= 0.75/1 = 0.75 that means minimum of 75% of the deer population must be immunized.
It can be interpreted that 75% immunization is may not be effective, to be effective it should be at least above 95%
True, higher R0 is more virulent ex: 1-1/10 = 0.9 (meaning 90% may have disease)
Pros: we can limit the spread of disease, induces herd immunity.
Cons: We may not immunize all wild population if we don’t know the exact number, if not done herd immunity may fail
Lizards acting as reservoir hosts for the pathogen Borrelia burgdorferi when infected ticks feed on lizards blood rather than mammals, this increases the pathogens ecological survivability with a new reservoir host along with a mammalian host like mice.