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42 Cards in this Set
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- Back
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Parasitology |
Study of medically important protozoa and multicellular parasites |
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Parasitology
Parasite (general sense) |
An organisim that lives in assoc w/ another org in a relationship in which one benefits and one is harmed |
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Parasitology
parasite (specific sense) |
-protozoa- are protists -helminths- are worms(animals) -arthropods- are instects (animals) |
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Ecto parasites |
live on surface of other organisms ex: tick |
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Endoparasites |
live w/in bodies of other org ex: tapeworm |
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Obligate parasites |
must spend at least some of their life cycle in or on a host, cannot complete life cycle w/o ex: mosquito |
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facultative parasites |
normally free-living but can also obtian nutrients from a host ex: fungus |
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Permanent parasites |
remian in the host, once infection is initiated ex: tapeworm |
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temproary parasites |
feed on host temporarily, then leave ex: mosquito |
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accidental parasites |
invade an org other than their normal host ex: swimmer's itch |
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definitive hosts |
harbor parasite during its sexual stage of reproduction |
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intermediate hosts |
harbor a parasite during another developmental stage |
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reservoir hosts |
infected hosts that make parasites available for transmission to another hose ex : Malaria -definitive- mosquito -intermediate-humans -reservoir- animals/other mammals |
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Protsists: Kingom protista
Characteristics |
-most are unicellular -Eukaryotic -usually free-livign and aquatic => some parasitic |
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Protozoa (animal- like protists) (microbes)
Characteristics |
-Eukaryotic -most unicellular -many are free-living; are parsitic as pathogens -heterotrophic- often ingest food particles and digest it after ingestion -reproduce by binary fission (asexual) => some reproduce sexually |
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Protozoa classified/grouped by means of locomotion |
-flagellates- move via flagella -amoebas- move with pseudopodia -ciliates- move with celia -apicomplexans- immobile, no motility in the adult stage, they digest their way into host cells => all above contain human pathogens |
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Helminths (not microbes)
Characteristics |
-wroms, kingdom animalia -eukaryotic -multicellular have head and tail ends -have bilateral symmetry -have complex life cycles, involve diff hosts and larval stages |
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Medically important helminths |
-flatworms: flukes, tapeworms -roundworms |
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Protozoa and Helminth Diseases
Virulence determinants of parasites |
Encystment- formation of resistant stage (a cyst) that protects against unfavorable conditions -amebiasis, giardiasis- cyst to enable transmission from host to host -taxoplasmosis- cysts in most feces, soil -tapeworm- cysts in muscle
changing its surface antigens- to avoid host immune response -malaria in the blood stream
living where parasite can't be reached by host's immune system -malaria, inside liver and rbc -tapeworm in intestinal lumen |
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Protozoa and helminth diseases
Characteristics |
-both can be parasitic -both can be eukaryotic - both lack cell wall -Host-parasite relationship: => rep bal. tween parasite's virulence and host's response => parasite burden/load: reletive amt of parasite infecting the host; is often quite low to facilitate tolerance of the infection -tend to be chronic infections |
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Parasites and Parsitic Diseases
Protozoa |
-Amoebas -Flagellates -Ciliates -Apicomplexans- malaria |
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Parasites and Parasitic Diseases
Helminths (worms) |
Flatworms -tapeworms-taenisasis -flukes- swimmer's itch
Roundworms- pinworm disease |
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Malaria |
A widespread and deadly parasitic disease plasmodium species (4)- apicomplexan protozoan -complex life cycle w/ 4 forms/stages |
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Malaria Stats |
Endemic in tropical areas -up to 500mill infect/year -kills about 800k/year (african children) -about 1500 in US travelers |
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Malaria transmission |
bit of infected mosquito |
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Malaria disease |
-sporozooites intially infect liver-> merozooites -they infect rbcs- ring-shaped form (trophozooites) -malarial attack: chills, fever, headache, delirium assoc. w/ rbc rupture and release of parasites; occur in cycles -parasites switch surface proteins to avoid host immune response -anemia develops->circulatory and kidney problems; high fever-> convulsions |
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Malaria diagnosis |
identify parasites in blood smear |
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Malaria treat and ctrl strat |
-anti-malarial drugs are effective, where avail. -drug resistance is common -prophylaxix for travelers to malaria endemic regions = prevention; admin of antimicrobial agen to prevent infect -ctrl mosquitoes and prevent of bites: insecitcide and bed nets -no vax avail |
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Taeniasis- tape worm infections |
taenia species- beef/pork tapeworm -flatworms that live in host intestine -scolex (head) w/ hooks and suckers -proglittids (seg) devel. behind head and mature as move back -mature seg disintergrate and relase eggs at tail -occurs ww, rare in US b/c good meat inspect -transmit by eat raw/undercookedmeat |
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Taeniasis- tapeworm infection
disease |
-cysts- eaten, dev. into tapeworms and live in intests (yrs) -absorptive metabolism -often asymptomatic, or mild abdominal symp, tolerance may dev. -larvae can invade bloodstream and spread to other body sites (CNS and form cyst) ->ruptures causing severe/fatal allergic response
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Taeniasis- tapeworm infect
diagnosis |
look for eggs or proglottids in feces
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Taeniasis- tapeworm infect
treat |
antiparasitic drugs will clear worm, may not get rid of cysts in tissue |
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Cercarial dermatitis (swimmer's itch) |
schistosoma species- flukes (flatworm) -cercaria is a larval stage of the parasite -occurs ww, locally, seasonally |
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Cercarial dermat (Swim itch)
transmission |
-while swim in water where parasites are located; cercaria burrow into skin -definitive-ducks -intermidiate- snails -accidental- humans |
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Cercarial dermat (Swim itch)
disease |
-red, patchy, pin-point rash that itches -devel. w/in 48 hr; resolves in 1wk -parasite goes no further than skin -must get from water, not skin to skin |
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Cercarial dermat (Swim itch)
diagnosis |
presentation and history |
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Cercarial dermat (Swim itch)
treat and ctrl |
-no anti-parasitic drugs avail; OTC anti-itch meds -towel off vigorously after swim -ctrl snails |
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Pinworm disease |
most prevalent helminthic infectin in US enterobius vermicularis- common name is pinworm; are roundworms -humans=only host -occurs ww, est. 40mill infect in US, most children |
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Pinworm disease
transmission |
fecal-oral route; ingestion of worm eggs |
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Pinworm disease
disease |
-eggs dev. into adult worms in 1mo. -male/female adult worm live in lg. intestine -females lay eggs in perianal folds at night -lgly asymptomatic, or anal itching, some diarhea -worms die w/in wks |
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pinworm disease
diagnosis |
cellophane tape test to look for wroms or eggs |
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pinworm disease
treat |
all members of family should be treated -easily spread, and may not know they have it -re-treat in 10-14 days because eggs may be in blankets etc. |
