Parasite%20Examples%20Assassin%20bugs%20(Triatoma)%20Malaria%20Tapeworms%20(Cestodes)%20Cholera%20(Shigella)%20transmission%20via%20dysentery%20Toilet%20seats,%20elevator%20buttons,%20shopping%20carts...%20Molecular%20mimicry%20

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Parasite ExamplesAssassin bugs
(Triatoma)MalariaTapeworms (Cestodes)Cholera
(Shigella) transmission via dysenteryToilet
seats, elevator buttons, shopping
carts...Molecular mimicryeclipsed antigens
resemble host antigenshence do not elicit
formation of host antibodiesMajor
Histocompatibility ComplexTrypanosoma shed
coats, change antigensFilariasis Elephantiasis
(blocked lymph nodes,nematode worms carried by
mosquitos)
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Botfly
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Botfly
Botfly larva
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Filariasis Elephantiasis (blocked lymph
nodes,nematode worms carried by mosquitos)
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Nematode (Roundworm)Dracunculus medinensis
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Dracunculus medinensis
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Host Altered Behavior Rabies virus rabid
animals bite Lancet fluke Trematode
Dicrocoelium dentriticum Cercaria gt
Metacercariae encyst on ants brain Sheep ingest
an ant and get infected Starlings, Pill bugs,
and Acanthocephalans Ducks, Amphipods, and
Acanthocephalans STDs gt increased sexual
activity?
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Ectoparasites, endoparasites Social
parasites ParasitePredator spectrum Microparasi
tes Macroparasites Parasitoids Predators Mode
of transmission virulence
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Comparison of Ecological Characteristics That
Vary Along a ParasitePredator
Spectrum _________________________________________
________________________________ Characteristic Mi
croparasite Macroparasite Parasitoid Predator ____
__________________________________________________
___________________

Body size Much
smaller Smaller than Mature stages Larger than
hosts hosts similar in size than prey Intrinsic
rate Much faster Faster than Comparable Usually of
population than hosts hosts but
slightly slower growth slower than
prey Interaction with One host One host One
host can Many prey host individuals usually
supports supports a few support seve- items
are in natural several popula- to many
indivi- ral individuals eaten by populations tions
of different duals of different each
predator species species Effect of the Mildly
to fairly Variable, not Eventually Usually inter
action on deleterious too virulent
to fatal immediately host individual definitive
can fatal be intermediate Stability of
the Intermediate High Intermediate Usually
low Interaction Ability to reg- Moderate Low Fa
irly high High ulate lower Trophic
level ____________________________________________
______________________
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Challenges facing Parasites, hosts as islands,
how to infect new ones? High specificity, high
fecundities, exploitation of vectors
(mosquitoes) Intermediate and final hosts, host
altered behavior (rabies, etc.) Assassin bugs
(Triatoma)MalariaTapeworms (Cestodes),
Nematodes (roundworms) Cholera (Shigella)
transmission via dysenteryToilet seats, elevator
buttons, door knobs, shopping carts...etc. Molecul
ar mimicry eclipsed antigens resemble host
antigenshence do not elicit formation of host
antibodiesMajor Histocompatibility Complex (MHC)
Trypanosoma shed coats, change
antigensFilariasis Elephantiasis (lymph nodes
blocked by nematodes carried by
mosquitoes) Botflies Dracunculus medinensis,
caduceus symbol of medicine
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Evolution of Virulence (benign parasites allow
hosts to live) Host altered behaviorRabies virus
rabid animals bite, passes on virus to new
host Lancet fluke Trematode Dicrocoelium
dentriticumCercaria gt Metacercariae encyst on
ants brainSheep ingest an ant and get
infectedStarlings, Pill bugs, and
AcanthocephalansDucks, Amphipods, and
AcanthocephalansSTDs gt increased sexual
activity? Ectoparasites (fleas, ticks, lice),
endoparasites Social parasites (thievery, brood
parasitism) Parasitoids Ichneumonid
wasps Microparasitesgt macroparastiesgtparasitoids
gtpredator spectrum and many correlates thereof,
such as relative sizes, rates of increase, number
of parasites per host, virulence, stability, and
ability to regulate lower trophic level
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Ebola zaire
Ebola reston
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Parasitism gt Commensalism gt Mutualism(, )
0 lt (, 0) lt (,
)Host-Altered BehaviorEvolution of
VirulenceBiological Control
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Brazilian cottontail rabbit Sylvilagus
brasilensis carried a benign myxoma virus which,
when injected into an Oryctolagus cunniculus
hare caused cancers that quickly killed the
rabbits. Released in 1951, epidemic killed 99.9
of bunnies but, rabbits being rabbits, bred like
bunnies, and soon there were as many as ever.
Second epidemic only killed 70 and the third
only 50. Resistent Rabbits evolved, but so did
the virus as it was spreading through the
rabbit population, the virus evolved reduced
virulence.
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