Parasitology Flashcards
Definitive host
Final life cycle
Reproduce here
Intermediate host
Go through multiple cycles/stages before transmitted to the definitive host
Paratenic host
Transport
No development here, just carrier
Mechanical vector
Carries part from animal to animal
Ex: horsefly
Prepatent period
Time from final definitive host to pick up and go through the life cycle
Can see diagnostic traits, ex: tapeworms (eggs in feces)
Patent period
Once eggs in feces, dx stages in feces
Once stops prepatent over
3 types of parasites
Protozoans
Helminths
Arthropods
Protozoans
Amoebas, ciliates, flagellates, and apicomplexans
Helminths
Worms
Platyhelminths, nematodes and acanthocephals
Arthropods
Insects, acarines, pentastomes, Crustacea
Symbionts
Living together
Phoresis
Traveling together
Commensalism
1 benefits and other is neither helped nor harmed
Obligate parasite
Cannot live without host, no free living stages
Ex: round worm, tick and mosquito
Facultative parasite
Can use matter and garbage to complete life cycle
Hyperparasitism
Parasite infecting parasite
Larval heartworm is a hyperparasite of mosquito- parasitizes develops
Parasitiasis
Infected but no outward signs of disease
Parasitosis
Outward signs of disease
Sylvatic cycles
Involve parasites of wild animals infecting humans
Urban or domestic cycles
Involve parasites of companion or food animals or domestic rats for cross over
Evolution
Parasites co evolved with host are less likely to be pathogenic
If recently colonized are more pathogenic, result of keeping animals in environment not well adapted to
Overdispersion
Not all animals harbor the same number of parasites and the level can vary
How to escape immunity
Molecular mimicry
Antigenic variation
Secretion of substance
Molecular mimicry
Mimic linear amino acid epitopes of the host
Plasmodium
Antigenic variation
Trypanosomes express new surface glycoproteins eluding destruction by the host
Secretion of substances
Block IgM so cytokine secretion is impaired
Ex: entamoeba evades humoral immunity by degrading Ab via proteases
Harmful effects of parasites
Suck blood, feed on solid tissue, compete with host for food, cause mechanical obstruction, cause pressure necrosis, destroy host cell via asexual repro and rupture cells, produce toxins, cause allergic response, cause host reactions to foreign body, stimulate neoplastic transformation of cells, carry disease and other parasites and reduce host resistance
Increase fecundity
Produce large number of eggs or cysts
Hermaphroditism and asexual repro
Infected IH more susceptible to ingestion by DH
Getting to host
Oral, infest, intermediate host, transmammary, transplacental, vector borne and skin penetration
Staying in place
Hooks Flukes- oral sucker Thorny Mouth Spines
Euryxenous
Infect wide variety of hosts
Stenoxenous
Host specific
