Lecture 24

Lecture 24 - Bio 121 Lecture 24 parasitism immunity and...

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Bio 121 Lecture 24 – parasitism, immunity, and disease A. Parasites – an introduction – organism that obtains its nutrients from a host a. Ectoparasites – parasites living outside the host a.i. Ticks, lice, etc. b. Endoparasites – parasites living inside the host b.i. Plasmodium, tapeworms, etc. c. Found in all 6 kingdoms of life d. More than half of all living species are parasitic e. Human parasites e.i. Hookworms – suck blood from inside of body e.ii. Shistosamisisis – malaria – causes anemia, chills, and fever e.iii. Ascarids – round worms, millions of people in US B. Model of host: parasite dynamics a. Three boxes represent 3 different types of hosts b. Arrows represents rates c. Persistence of parasites c.i. R=average number of secondary cases that an infect host gives rise to during its life if it’s introduced to a susceptible population c.ii. R=(beta)N/(alpha + d + V) c.iii. N = population size of susceptible hosts (increased by births and loss of immunity) (decreased by death and infection) c.iv. Beta*N = rate of new infection c.v. 1/alpha+d+V = rate at which infection decreases
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Lecture 24 - Bio 121 Lecture 24 parasitism immunity and...

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