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