Parasitology Exam 1 Flashcards
direct life cycle
no intermediate host
indirect life cycle
definitive host + 1 or more intermediate hosts
transmission often linked to predator-prey relationships or vector-vertebrate interactions
symbiosis
4 types
any 2 organisms living in close association, commonly one living in or on the body of the other
commensalism, mutualism, phoresis, parasitism
commensalism
one benefits and the other is not helped or harmed
facultative
mutualism
both benefit, usually obligatory where one cannot survive without the other
cleaning phenomena between fish
phoresis
travel together with no physiological/biochemical dependence; mechanically carried
bacteria on legs of flies
parasitism
either harms the host or lives at the expense of the house = mechanical injury or robbing host of nutrition
endoparasites
helminths, flukes
exoparasites
fleas, ticks
obligatory parasites
cannot complete life cycle without spending part of time in parasitic relationship; many have free-living stages outside of host or time in environment with protective egg wall or cyst
facultative parasites
not usually parasitic but can become so if accidentally eaten or enter a wound
e.g. free living amoebas or nematodes
accidental parasites
do not survive in wrong host but may be pathogenic
e.g. toxoplasma
temporary/intermittent parasites
mosquitos or bedbugs
definitive host
parasite reaches sexual maturity
often vertebrates
intermediate host
required for development, sexual maturity is not reached
paratenic or transport host
no development, parasite remains alive and is infective to next host
bridge an ecological gap
reservoir host
animal harboring infection that can be transmitted to humans
host specificity
some parasites are host specific
e.g. Coccidia
What are some examples where we are seeing anthelmintic resistance in our animal populations?
coccidia resistance in poultry
How might parasites contribute to financial loss in herds?
By killing numerous animals in a herd, the production will decrease
How do crowded stressful conditions contribute to parasitism?
In pastures/pens of domesticated animals, eggs/larvae/cysts can become dense in the soil and if adult parasites infect the host it can be devastating
Coccidia thrives in crowded conditions
What are life stages? Can you provide examples?
trophozite: active, feeding, multiplying stage (e.g. giardia)
cyst: protective membrane/thickened wall so they can survive outside the host
oocysts: coccidian form of a cyst
Why are cysts an important life stage adaptation?
Helps parasites live in environments with harsh conditions (food deficiency, desiccation, low O2, pH or temperature change)
Nematodes
bilaterally symmetrical
elongated
tapered at both ends
pseudocoelomate
complete digestive system
Platyhelminths
found in many environments
bilaterally symmetrical
dorsoventrally flattened, some elongated
lead-shaped or ovoid in form
acoelomate
distinct anterior end
sensory/motor elaborate nervous system
cestodes have no digestive system
trematodes have a digestive system
cestodes
tapeworms
-no digestive system
-monoecious organisms
-strobila (segments)
-sucker/grooves/hook/spine/glands /tentacles
trematodes
fluke
-digestive system is blind sac w/ anterior mouth, muscular pharynx, EC digestion
-undigested waste go through mouth
protozoans
most habitats
commensal & parasitic
microscopic, single-celled, 1+ nuclei
immunologic, varibale size, surface proteins
use pseudopodia, flagella, cilia for locomotion
sexual/asexual reproduction
trophozoites or cysts
3 types of protozoans
diplomonadidae - flagellates (giardia)
trichomonadidae - thousands of flagella
trypanosomatidae - kinetoplasts
arthropods
vectors several groups of pathogens
invertebrates
segmentation
hard exoskeleton + appendages
discrete mm.
monoecious/hermaphroditic
having both male and female reproductive organs in the same individual
e.g. nematodes, trematodes, cestodes
dioecious
male and female reproductive organs in separate individuals
e.g. nematodes & trematodes
acetabula
specialized sucker for parasitic adaptation to attach to host; cup shaped, ovoid, muscular structure
e.g. cestode (tapeworm)
name parts of a tapeworm
proglottids (each segment of strobila)
strobila (segmented part)
scolex (head of tapeworm)
rostellum (knob-like protrusion at anterior end)
holdfast organ
an organ by which a parasitic organism attaches itself to a host
cestodes
parthenogenetic
asexual reproduction
nematodes
oviparous
producing young by the means of eggs that are hatched after laid by parent
nematodes
ovoviviparous
producing young by the means of eggs that are hatched within the body of the parent
nematodes
triradiate
having or consisting of three rays or radiating branches
pharynx or esophagus of nematodes
kinetoplasts
protozoans with DNA containing region in a single large mitochondrian
flagellates
protozoans that have flagella
