parasitology 1 Flashcards
what is a parasite
organism that lives in or on another living organism (host) obtaining from it all or part of its nutrients
cause harm to the host
some degree of adaptive structural modification
only include those organisms that are eukaryotes except fungi
direct life cycle
simple
one host
indirect life cycle
complex
2 or more host
definitive host
host in which sexual reproduction takes place
final host
intermediate host
host in which only immature stage grow and develop
may or may not occur asexual reproduction
paratenic host
host not required to complete the life cycle but help parasite get to the host
no parasitic development of any kind takes place
transport host
normal host
animals recognized as part of the normal life cycle
abnormal, aberrant host or dead end
animal not normally used as a host
often (not always) associated with disease
animals could be abnormal definitive, intermediate or transport host depending on which stage of the parasite life cycle is present
reservoir host
host serves as as ource of infection for other animals
vector
invertebrate, usually arthropod that transmits infectious disease
biological vector
parasite develope in the vecctor
mechanical vector
like a contaminated instrument
endoparasite
internal parasite
infection
ectoparasite
external parasite
infestation
microparasites
multiple inside host
macroparasites
mate, produce eggs and leave in the environment
does not multiple inside the host
infectious
caused or capable of being communicated by infection
infective
parasite stage capable of infect the host
many parasites are not able to cause infection until after some period of development in the environment
prepatent period
internal parasites-mainly macroparasites
time required following infection of the definitive host to reach repdocutive maturity (secual reporuction) period before production of eggs/cysts
not the same as the generation time :egg to egg
patency
adult reproductive infection
will an exposed animals become infected
parasite usually require appropriate stimulus to recognize potential host
intracellular parasite need specific receptors on cells of appropriate hosts
GI helminths often need specific cues like pH and bile
pathogenesis depends on three factors
status of host defenses
number of parasites present
pathogenicity of those parasites
pathology from parasitic infections
parasite-induced trauma to the cells, tissue and organs
changes in cellular growth patterns
interference with host nutrient acquisition
toxins released by parasites
the host immune response to infection
70-30 rule
top 30% has 71% of the worms
bottom 70% has 29% of worms