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94 Cards in this Set

  • Front
  • Back
Protozoans are commonly spread via the
fecal oral route. often transmitted by food that becomes contaminated with human or animal wastes
protozoans are
single celled animals and eukaryotic. most are motile
Amoebiasis characteristics
protozoal GI disease; motility via psuedopods; most transmission via fecally contaminated water or food
organism of Amoebiasis:
Entamoeba histolytica is the most common cause of amoebic disease
Amoebiasis infxn occurs when we
eat/drink cysts in fecally contaminated food/water
IN amoebiasis, the cysts mature into
trophozoites near the juntion of the small and large intestines where they digest the intestinal wall to form ulcers:
s/s of amoebiasis infxn
bloody stools, but little diarrhea
amoebiasis may also
invade the bloodstream and travel to organs such as lung or liver to cause lethal disease.
in amoebiasis, fecal contamination can come from
humans or animals
amoebiasis incidence is
higher in areas of poor sanitation and among male homosexuals
Giardiasis characteristics
protozoal GI; motility via flagella; most common infectious protozoan in US
organism of Giardiasis:
Giardia lamblia. common in US in hikers and other outdoors people (thousands of infxns/y
Giardia lamblia contaminate
water from human and other animal fecal material and are resistant to chlorine (or other halogen) tx of water.
Giardiasis development
cysts develop into flagellated trophozoites in the intestine where they attach to intestinal villi.
Giardia trophozoites look
like a smiley face because they contain 2 dark nuclei (eyes) and a curved central plate (a foundation for the four pairs of flagella) that frequently looks like a smiling mouth
s/s Giardia:
cramps, nausea with odiferous flatulence
Cryptosporidiosis characteristics:
protozoan GI; watery diarrhea; nonmotile; small oocysts are the infectious form (about ten microns); common in dogs, cattle, and pigs
organism of Cryptosporidiosis:
Cryptosporidium parvum
Cryptosporidium parvum causes
diarrhea for 1-2wks in normal pts; a profuse diarrhea in immunocompromised pts who may dehydrate like choler pts and often die of the disease
Cryptosporidium parvum invade
epithelial cells of the intestinal tract and grow into them
Cryptosporidium parvum transmission:
besides fecal oral route, it is transmitted directly in day care centers and has been on the rise since the mid 1970s
Cyclosporiasis characteristics
protozoal GI; nonmotile/ large oocysts initiate infxn (about 30 microns); found recently in imported berries and vegetables
Cyclosporiasis was first identified
in 1986 in travelers from Mexico and Caribbean
Cyclosporiasis s/s
watery diarrhea, cramps, and vomiting persist for a month or more
from 1996-98 the parasites (Cyclospora cayetanensis were transmitted from
raspberries from Guatemala. the farmers have had to improve their water quality and sanitation.
Balantidiasis characteristics:
protozoan GI; motility by cilia; large 70x100 microns; single celled protozoan.
organism of Balantidiasis
Balantidium coli, is the only major human disease caused by ciliates
B. coli are
very large, up to 0.1 mm in diameter and are completely covered with cilia. acquired from undercooked food, especially pork and water.
B. coli cysts
pass thru stomach, and trophozoites develop in the intestines where they cause mild ulceration
s/s of Balantidiasis
Nausea, profuse diarrhea, weight loss
B. coli cases in US
are rare, however there is concern that travelers from tropical regions may bring the disease to this country
it is est. that 2 billio people are currently infected with the flatworms and roundworms called
helminths
flatworms are called ____________ and roundworms are called_________
platyhelminths
aschelminths or nematodes(because of the shape)
flatworms are often
hermaphroditic - they have both male and female sex organs in each animal
roundworms have
separate sexes
most helminths produce
eggs or larvae that pass out of the hosts body for development
helminths vary from
small single celled flukes to tapeworms that may reach 25' in length. they are discussed with microbes d/t their relatively small size and ability to cause disease
flukes
flat (leaf shaped) single celled parasites with complex life cycles that contain egg stages and larvae forms
flukes attach to
their hosts by means of suckers. often they have 2 different hosts as part of their life cycle
the larvae form of flukes
grows in the intermediate host and the adult (sexually mature) form grows in the definitive host. If growth in either host can be interrupted, transmission may be prevented
Schistosomiasis characteristics:
GI helminth; motility via powerful tails called cercaria; each fluke infects and develops in a fluke specific snail before infecting humans; the human is the definitive hsots, where the sexually mature forms of flukes are found
organism of Schistosomiasis
Schistosoma mansoni, S. japonicum, S. haematobiu, and infect 200-500million people worldwide. the four different species are found in different areas of the world
Schistosomiasis are
multicellular with primitive circulatory and nervous systems
Schistosomiasis life cycle
cercaria (tadpole, highly motile) penetrate skin w/contact of contaminated H2O. to liver via blood & male/female mate = eggs excreted in ua/feces. eggs hatch into motile forms called miracidia & swim til find snail (intermediate host). cercarie develop in snail, escape, find new human (continue cycle). each species has its own particular snail as a host.
eggs of Schistosomiasis
build up until liver damage. intenstinal wall/bladder may have damage.
s/s of bladder infection in Schistosomiasis:
bloody urine and painful urination
Cercaria of other species whose normal definitive host is a
bird or other animal can infect humans but stay at the site of infxn to cause dermatitis or swimmer's itch. (northern lakes of US)
Tapeworms characteristics:
GI parasite; flat worms with many segmented proglottids, nonmotile
tapeworms consist of
a head with many flat segments that form the body. the head is called a scolex
tapeworm scolex has a
hook or sucker for attachment to the infected tissue and many individual segments are attached to it. each segment is called a proglottid which is essentially a uterus
new proglottids form
behind the scolex to grow and produce eggs, and are displaced further from the head so that at the end of the tapeworm, single large proglittids break away and spread thousands of eggs.
the beef tapeworm
may have 2000 proglottids and span 25' in length
Taenia saginata and T. solium
are the beef and pork tapeworms respectively.
proglottids
are eaten by the approprate animal and hatch into embryos that encyst (form cysts) in the animals muscle
when contaminated, undercooked meat is eaten,
cysts develoop into the tapeworm that attaches to the lining of small intestine to utilize nutrients
s/s of tapeworms:
most cases result in few sympotmos except for minor dirrhea
sometimes tapeworms
grow to large #s and block the intestinal tract
occassionally a person will ingest T. solium eggs
that migrate to the brain, grow into cysts, damage brain, cause neurologic s/s
less often fish or dog tapeworms are
also known to infect humans
roundwormsaka
nematodes, live in all soils and waters, infect every kind of plant and animal known. billions/acre of land - cause tremendous damage to other life.
Pinworm characteristics
parasite, roundworm, body is muscular, as seen in common garden worms
the pinworm is known as
enterobius vermicularis is the most prevalent helminth in kids. 30% of kids, 16% adults serve as hosts in US
adult females of enterobius vermicularis
aka pinworms living in colon migrate to anus at nite, lay eggs in perianal folds, and pruritis (itching) develops
spread of enterobius vermicularis/pinworm
is via kids scratching then touching other objects/kids. reinfection occurs when they put fingers in their mouths
detection of enterobius vermicularis is
by use of clear cellophane tape pressed against anal area and then observed microscopically on a glass slide for pinworm eggs.
Whipworm characteristics
whip like structure, muscular roundworm
whipworm is called
trichuris trichiura d/t long slender shape that resembles a bullwhip
trichuris trichiura/whipworm attaches
to the junction of the small and large intestines and damages surrounding tissue by whipping movements of its 40mm long body.
trichuris trichiura/whipworm ingests
enough blood to cause anemia in some infxns
trichuris trichiura/whipworm eggs
are passed out in feces and require about 2 wks in soil to develop into infectious larvae
infection of trichuris trichiura/whipworm occurs
when people consume food/water contaminated with the larvae.
high prevalence of trichuris trichiura/whipworm
is favored by heat, moist climates, and poor sanitary facilities.
adult females of enterobius vermicularis
aka pinworms living in colon migrate to anus at nite, lay eggs in perianal folds, and pruritis (itching) develops
spread of enterobius vermicularis/pinworm
is via kids scratching then touching other objects/kids. reinfection occurs when they put fingers in their mouths
detection of enterobius vermicularis is
by use of clear cellophane tape pressed against anal area and then observed microscopically on a glass slide for pinworm eggs.
Whipworm characteristics
whip like structure, muscular roundworm
whipworm is called
trichuris trichiura d/t long slender shape that resembles a bullwhip
trichuris trichiura/whipworm attaches
to the junction of the small and large intestines and damages surrounding tissue by whipping movements of its 40mm long body.
trichuris trichiura/whipworm ingests
enough blood to cause anemia in some infxns
trichuris trichiura/whipworm eggs
are passed out in feces and require about 2 wks in soil to develop into infectious larvae
infection of trichuris trichiura/whipworm occurs
when people consume food/water contaminated with the larvae.
high prevalence of trichuris trichiura/whipworm
is favored by heat, moist climates, and poor sanitary facilities.
s/s of trichosis
n/v abd pain, constipation
in trichosis larvae are also produced
in humans that migrate in encyst in the diaphragm and mucles required for eye movement as well as in the brain.
in trichosis the cysts cause
pain and restrict the use of muscles, can cause paralysis when they form in brain and can damage/restrict motor neuron function
to reduce trichosis
pickling, smoking, and freezing pork reduces but doesn't eliminate viability of cysts; cooking does completely kill them
when people eat pork containing cysts of trichinosis
that have not been killed, the cysts pass into the intestine where they become worms that attach and grow
hookworms characteristics
parasite, roundworm, larvae have hooks that attach to bare feet
2 hookworms that infect hundreds of millions of people
ancylostoma duodenale and necator americanus
hookworms attach to
human intestines and cause anemia by sucking blood
lifecycle of hookworms
involves a single host- the human. eggs pass out in feces to soil where they develop into larvae that have hooks and attach to bare feet, penetrate bloodstream travel to hungs, cough up and swallowed, attach to intestines
hookworms are common where
soil is wet, warm and sanitation is poor
hookworm are more common in
the southern US
hookworms are also carried by
cats and dogs