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145 Cards in this Set
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Enterobius Vermicularis (pinworm) Lifecycle?
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- Eggs in environment become infectious w/in 4-6 hours
- eggs are eaten - eggs hatch in intestine - worms grow to adults in 6 wks -Adult migrates to perianal skin and lays eggs - if not eaten, eggs die in 2 weeks |
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Pinworm Infectious Form?
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Egg w/ differentiated larva inside (gets ingested)
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Pinworm Dx?
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Egg which is flatter on one side than other
- Found @ perianal skin - Scotch Tape Diagnosis |
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Pinworm Treatment?
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MEBENDAZOLE--Must treat once then again later to treat infection that will have re-curred from swallowing eggs in environment from first infection
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Ascaris Lumbricoides Infectious Form?
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Egg w/ larva inside (gets ingested on plants)
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Ascaris Dx?
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Egg w/ characteristic bumpy shell and larva inside (found in feces?)
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Ascaris Symptoms?
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- Can cause intestinal or bile duct obstruction
- Malabsorption of Lactose |
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Hookworm infectious form / route of infection?
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LARVA get in thru unbroken skin
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Hookworm Disease Causing Form
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Adult worm in small intestine
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Hookworm Symptoms
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Chronic blood loss
- (anemia, fatigue, SOB, developmental delay, edema) |
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Hookworm diagnostic stage
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eggs found in stool
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Strongyloides Infectious Form / Route of Infection
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Filariform larvae
- Penetrate skin |
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Strongyloides Diagnostic Stage
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Rhabditiform (1st stage) larvae in stool
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Strongyloides Causes of Hyperinfection
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-Steroids
-Bacterial Sepsis |
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Visceral Larva Migrans (Toxocara)
- Infectious Form / Route of infection? |
(Kids) Ingest the eggs
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Visceral Larva Migrans Disease Presentation
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-Eosinophilia/Inflammation
- Altered LFTs - Various Symptoms - Invasion of retina resembling retinoblastoma |
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Visceral Larva Migrans Dx?
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- Serology! (wont usually larva or egg)
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Cutaneous Larva Migrans infectious form/ route of infection?
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Filariform (3rd stage) Larvae
- Penetrate skin |
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Cutaneous Larva Migrans disease-causing form?
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Larvae (can't mature to adults in humans!)
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Cutaneous Larva migrans dx?
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- Eosiniophillic inflammation on biopsy of serpiginous lesion
- (infrequently can see actual larva) |
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Trichinella Spiralis Infectious Form/ Route of Infection?
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- Larva encysted in muscle of carnivore is eaten
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Trichinella Spiralis Diagosis?
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Finding encysted larva in muscle
- "Squash Test" on a piece of fresh muscle tissue shows encysted larvae - Can also use serology if there is not a good place to biopsy |
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Trichinella Spiralis Life Cycle in humans?
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Larva ingested, mature to adults in small bowel
- Adults mate and produce new larva (no eggs!) - Larva migrate thru bowel->portal circulation-->muscle |
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Trichinella Spiralis disease mechanism?
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Larva in muscle induce inflammation!
- Heavily used/ oxygenated muscles preferred (heart, diaphragm, peri-orbital) |
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Filaria (General) Life Cycle?
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- Adults in SC nodules / lymphatics
- Produce larvae in blood stream - Vector bites and gets infected w/ larvae thru blood - Larvae matures thru several stages in vector - Mature larvae passed back to human thru bite |
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Lymphatic Filariasis (Wucheria) Infectious form / Route of infection?
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Mature larval form transmitted through mosquito bite
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Lymphatic Filariasis (Wucheria) Disease causing form / Disease mechanism?
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Adults in lymphatic system cause lymphatic obstruction-->elephantiasis
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Lymphatic Filariasis (Wucheria) Diagnostic form?
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Microfilaria (larva) in blood
- show distinct pattern of nuclei - faintly staining sheath is present |
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Dirofilaria (Dog Heartworm) Manifestation in humans?
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Larvae don't mature in humans but can be deposited in lung and form fibrotic lesion
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Onchocerca Disease Causing form/ Disease Mechanism / Disease manifestations?
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Microfilaria (larva) migrating through dermis and causing inflammation
- chronic, atrophic, dermatitis - blindness (whole eye affected) |
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Onchocerca Infectious form / route of infection?
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Infective Larva transmitted by BLACK FLY bite
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Onchocerca Diagnosis?
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Skin snip--ID microfilaria in dermis
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Onchocerca Treatment?
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Ivermectin administered 1X/year-- kills microfilaria in blood and prevents disease manifestations
- does NOT kill adults in SC nodules |
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Schistosomiasis Indermediate Host
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SNAIL
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Schistosomiasis Life Cycle
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Ciliated larva hatches from egg--infects snail--cercariae larva (swimming form) breaks out of snail--penetrates human skin (loses tail)--portal system-->matures to adult-->paired adult worms in mesenteric v. or bladder--shed eggs into feces or urine-->hatch to ciliated form in water
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Schistosomiasis Habitat
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FRESH WATER
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What causes Disease in Schistosomiasis?
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Overactive immune response to Eggs trapped in organs
-TH2 response-->granuloma-->massive proliferation of fibrosis |
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Organs that Can be Damaged in Schistosomiasis
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Liver--pipestem Fibrosis-->portal htn, ascites
Lung Brain Spinal Cord Bladder--SCC |
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Species of Schistosomes / Characteristics
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Mansoni: lateral spine--excreted in feces
Hematobium: spine at end--secreted in urine Japonicum--no spine, rounder egg--secreted in feces--has zoonotic host |
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Diagnosis of Schistosomiasis
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Look for eggs in stool/urine
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Treatment of Schistosomiasis / What stage does it kill?
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Praziquantel
- Kills adult forms only |
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Prevention of Schistosomiasis
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Snail monitoring
Prevent human waste from reaching water |
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Schistosomiasis Infectious Form
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Cercariae Larvae--penetrate skin
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Taenia Saginata/Solium Infectious Form:
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Encysted larva in meat of beef/pork
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Taenia Saginata Intermediate Host
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Cow
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Taenia Solium Intermediate Host
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Pig
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Taenia Saginata / Solium Diagnostic Stage
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Egg or Proglottid in Stool
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Differences in appearance between Taenia Saginata & Solium
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Saginata: uterus in the proglottids has smaller but more numerous branches
Solium: scolex has a "circle of hooklets" in addition to 4 suckers - uterus in proglottids has larger but fewer branches -Eggs are indistinguishable |
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Taenia Lifecycle
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-Cow or pig eats egg or proglottid in human feces
- Larval form migrates to animal muscle - Human eats encysted larva in undercooked meat - Larva matures in s.intestine-->adult - Adult produces eggs--shed in stool |
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Taenia Saginatum Clinical Sx
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None
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Taenia Solium Clinical Sx
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Human can act also as intermediate host--larva encysts in muscle, brain, heart, bone, eye--"Cysticercosis"
- can cause epilepsy |
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Dx of Cysticercosis
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When larvae die--cysts calcify and can be seen on xray
(cysts of trichinella are too small to be seen on xray) |
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Tx for Taenia
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Praziquantal for adult worms +
Albendazole for larvae in t.solium |
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Diphyllobothrium Latum Diagnostic Stage?
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(Freshwater fish tapeworm)
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Egg in feces
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Fish Tapeworm Intermediate Hosts
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- Copepod crustacean
-Fish |
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Fish Tapeworm infectious stage
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larva encysted in muscle of undercooked fish
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Definative Hosts for Fish Tapeworms
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Humans
Cats Dogs Pigs |
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Fish Tapeworm lifecycle
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Eggs in human feces-->into water-->ciliated larva hatches-->infects copepod->eaten by fish-->larva encysted in fish muscle-->eaten by human
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Diphyllobothrium Latum (Fish Tapeworm) Differences from other two tapeworms (taenia)
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- Gets longer! (up to 75 ft)
- Shorter, broader proglottid - Eggs have a small "hatch" at one end - Release more eggs / day |
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Fish Tapeworm Clinical Symptoms
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Adults in small bowel-->interfere w/ B12 absorption-->macrocytic anemia
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Anisikiasis
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Assoc. w. saltwater fish
- larvae encysted in fish muscle--eaten by humans (sushi!) Larvae cause pain/eosinophilic inflammation ~72 hrs -human=accidental host |
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Echinococcus Granulosus Hosts
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Definitive: Dog (Dog Tapeworm)
Intermediate: Sheep Accidental Intermediate: Human |
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Echinococus Granulosus Route of infection of humans
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Eating eggs that were in dog feces
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Echinococcus Granulosus Life Cycle in Humans
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Ingest eggs--larva break out--migrate to liver/bone/brain--form Hydatid Cysts--asexual repro--production of protoscolices ("hydatid sand")
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Echinococus Granulosus Clinical Manifestation
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Leakage of cyst contents in response to trauma--acute allergic rxn (anaphylaxis) and seeding of new cysts
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Echinococus Granulosis Tx
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Surgery to remove cysts (careful not to rupture)
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Echinococcus Mulitlocularis Hosts
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Definitive= dog/fox
Indermediate=rodent Accidental intermediate=human |
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Echinococcus Multilocularis Clinical Disease
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Cysts w/ protoscolices can rupture SPONTANEOULY
- daughter cysts invade organs like malignant tumor (make surgical removal difficult) |
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Echinococcus Multilocularis Geographical Distribution
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Alaska, Northern MN, Canada, Circumpolar
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Entamoeba Histolytica Clinical Syndrome
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Amebic Dysentary: Acute colitis w/ flask-shaped ulcer
- blood and mucus in stool - abd pain - fever - steroid may activate disease-->perf. colon -"STERILE ABSCESS" in liver, brain, lung, skin |
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Entamoeba Histolytica Virulence Factor
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Amebic Surface Lectin--allows it to invade GI + Complement resistace
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Entamoeba Histolytica Life Cycle
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-Cyst in environment (v.stable--resist Cl-)
- Cyst swallowed (fecal/oral)--trophozoite breaks out--invades GI -Trophozoite changes back to cyst--excreted in feces |
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Entamoeba Histolytica Diagnosis
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Cysts (round w/ chroamotidal bars) and Trophozoite (single nucleus and occassionaly RBC inside) in feces
- difficult to ID the trophozoites b/c look like Macros - Ag detection of surface lectin=best |
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Entamoeba Histolytica Tx
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Metronidazole kills trophozoites
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Entamoeba Coli
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Not pathogenic, but used as marker of having been exposed to contaminated food/water--look for e.histolytica
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Naegleria Fowleri Clinical Sx
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Primary Amebic Encephalitis
- nasal passages exposed to amebae--they invade cribriform plate-->necrotic lesions of brain - rapidly lethal (wks-days) |
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Naegleria Fowleri Geographic Distribution
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Mid-atlantic states, southern US
- Warm ponds |
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Giardia Lamblia Life Cycle
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- Cysts in environment (v. stable-resist Cl-)
- cyst ingested (contam food/water) - trophozoite breaks out in s.bowl - trophozoite multiplies w/in GI and adheres to epithelial cells - Cysts and trophozoites Exreted in stool |
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Giardia Lamblia Clinical Sx
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- trophozoite covers surface area for absorption-->MALABSORPTION
- Steatorrhea (floating stools) - Diarrhea, abd discomfort, wt loss - Chronic inf: may be asymptomatic |
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Giardia Lamblia Dx
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Cyst and Trophozoite in Stool
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Giardia Lamblia Tx
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Metronidazole kills trophozoites
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Giardia Lamblia Geographic Distribution
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All over world!
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Trichomonas Vaginalis Infectious Stage
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Trophozoite in vagina or urethra
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Trichomonas VAginalis Dx
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Trophozoite in vaginal or prostatic secretions or urine
- wet mount to look for flagellated trophozoite - rapid enzyme immuno assay will probably replace other techniques |
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Trichomonis Vaginalis Replication
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- No cyst stage
- multiplies by binary fision |
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Trichomonas Vaginalis Clinical Syndrome
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- vagintis w/ purulent discharge
- urethritis - prostatitis - often asymptomatic - inflammation increases risk of HIV acquisition |
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Trichomonas Vaginalis Transmission
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- Sex
- Wet towel/ bathing suit |
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Trichomonas Vaginalis Tx
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- Metronidazole (both partners!)
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Toxoplasma Gondii Definitive Host?
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Any type of Cat
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Toxoplasma Gondii Infectious form
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Fecal cyst excreted by cat--infectious 2 days after excretion and remains infectious in soil for long time
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Toxoplasma Gondii disease causing form
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Trophozoite--rapidly dividing stage--invades tissue in muscle and brain
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Toxoplama Gondii route of human infection?
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Eating animal meat with tissue cyst OR ingesting fecal cyst from soil
(Dogs may roll in cat poop and human pats dog) |
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Toxoplasma Gondii primary infetion symptoms
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Usually asymptomatic! Sometimes mono-like symptoms or more severe in immunocompromised only
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Toxoplasma Gondii Reactivation disease?
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Toxoplasma Encephalitis--AIDS defining lesion
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Toxoplasma Gondii Congenital Disease?
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CNS (encephalitis) and Ocular (retinitis) manifestations
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Toxoplams Gondii Treatment?
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Pyrimethamine-Sulfadiazine (Anti-folate)
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Toxoplasma Gondii Diagnosis
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Serology (IgG and IgM)
- dont ever really find the dividing stage in people |
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Cryptosporidium route of transmission
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Usually contaminated water (cysts are resistant to chlorination--water must be filtered)
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Cryptosporidium infectious form
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Infectious cysts in feces-->contaminate water sources
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Cryptosporidium life cycle in human
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Infectious cyst ingested-->multplies intracellularly just under the plasma membrane in s.intestine epithelial cells-->excreted back out to environment
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Cryptosporidium Clinical Manifestations
(normal vs. AIDS) |
Normal: self-limited watery diarrhea
AIDS: protracted and debilitating diarrhea |
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Cryptosporidium Tx?
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None---symptomatic for diarrhea
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Cryptosporidium Diagnosis
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Acid Fast Cysts in stool
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Plasmodium Falciparum Life Cycle
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Sporozoite injected by mosquito in to blood-->infects hepatocytes->matures to merozoite-->infects RBCs-->infects more RBCs-->gametocytes eventually form-->M and F gametocyte must be transferred back to mosqito
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Plasmodium Falciparum Disease Causing Mechanism
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Merozoite digests Hgb w/in feeding vacuole in red cell-->hepatosplenomegaly from malaria pigment
When it breaks out of RBC--cytokines released-->periodic fevers + ANEMIA Parasitic proteins inserted in RBC membrane-->adhere to endothelial cells in small blood vessels-->ischemia (renal fail, cerebral dysfunction) |
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Plasmodium Falciparum Initial Clinical Presentation
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Shaking chills X 1 hour + h/a--> fever, n/v-->drenching sweat
- fevers become periodic after several weeks |
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Plasmodium Flaciparum Dx
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Blood smear (thin and thick film) too look for RING STAGE or BANANA SHAPED GAMETOCYTE in red cells
PCR is more sensitive--but only at ref. lab, results take several days |
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Plasmodium Vivax Differences from Falciparum
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- Milder Clinical Course, lower parasitemia, fewer complications
- can be dormant up to 12 months and then RELAPSE (survives winters) |
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Plasmodium Vivax Diagnostic Features
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- Infects Retics only so infected cells will larger than others
- Will likely see other forms besides ring stage - Schuffner's Dots |
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Alternative Pathways of Malaria Transmission
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- Transfusion
- Transplacental |
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Genetic Defects that confer resistance to Malaria
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- G6PD
- Sickle Cells trait - Duffy blood Ag |
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Malaria Tx (primary infection)
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- Chloroquine (oft. resistant)
- Mefloquine - Atoavaquone - Artesunate |
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Malaria Tx for relapse prevention in plasmodium vivax
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Primaquine
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Babesia Microti Definitive Host
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Ixodes Tick
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Babesia Microti Life Cycle
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Sporozoite injected into human by tick, has erythrocytic life cycle (merozoite) similar to that of p.falciparum
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At-Risk patient population with Babesia Microti
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Asplenic Patients
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Geographic Distribution of Babesia Microti
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NE, West Coast, Southern US, Europe
- Especially NE coastal islands--NANTUCKET/ MV |
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Babesia Microti Dx
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Look at blood smear--can be difficult to distinguish from malaria, but difference is Babesia CAN be found extracellularly, malaria can not.
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Babesia Microti Tx
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Mild/Asymptomatic Disease: none
Symptomatic Disease: Combo tx - atovaquone and azithromycin OR - quinine and clindamycin |
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Babesia Microti commonly co-infected with?
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-Borellia Burgdorferi (Lyme Dz)
- Anaplasma Phagocytophilum |
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Hemoflagellates
-Leishmaniasis -Chagas (Trypanosoma Cruzi) - Sleeping Sickness (Trypanosoma Brucii) Common Characteristics? |
- All have a blood stage
- All have flagella originating from a kinetoplast - SOME have obligate intracellular stage AMASTIGOTE - All have insect host/ vector - Definitive host=u/k |
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Leishmaniais Insect Host
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Sandfly "Phlebotomus"
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Leishmaniasis Life Cycle
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Sandfly injects flagellated form-->enters monocyte in skin-->loses flagella-->mult. intracellularly as amasticgote-->cell lysis-->more monos/macros infected-->uninfected fly ingests infected macros-->they become extracellular flagellated form and mult in insect GI-->infectious 1-2 wks later
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Leishmaniasis Diagnositic Stage
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Intracellular Amastigote on histology (see 2 dark staining bodies inside each parasite)
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Leishmaniasis Clinical Syndromes
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- Visceral (Kala Azar)
- Cutaneous - Mucocutaneous |
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Visceral Leishmaniasis clinical manifestations
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- wasting, hepatosplenoegaly, likely fatal
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Visceral Leishmaniasis Dx
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BMBx--original cutaneous lesion healed before visceral sx appear
(look for intracellular amastigote) |
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Cutaneous Leishmaniasis Clinical Appearance
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Papule at site of bite that grows and becomes ulcer that last 6mos-->years
- heaped up edge, center clears first, wet or dry |
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Cutaneous LEishmaniasis Dx
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- Biopsy along edge of ulcer
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Mucocutaneous Leishmaniasis Clinical Presentation
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STarts like cutaneous form, but weeks-years later it disseminates to produce massive necrotizing lesions at mucocutaneous junctions of mouth or nose
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Leishmaniasis Tx
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Difficult--available agents are toxic
- Amphotericin B for visceral - Antimony compounds--very toxic |
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Trypanosoma Cruzi Insect Vector
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Reduvid bug
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T. Cruzi mode of transmission
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Reduvid bug bites human and defecates, feces contain extracellular flagellated form--gets spread into bloodstream thru site of the bite
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Trypanosoma Cruzi Geographic Distribution
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S. America, Central America, Mexico
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T. Cruzi Life Cycle
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Flagellated form into blood via reduviid bug-->enters monos/skeletal& cardiac muscle-->becomes amastigote and multplies intracellularly-->flagellated forms break out of cells and infect others-->extracellular forms ingested by reduviid bug-->multiply in gut of bug and mature to infectious form in rectum
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Trypansoma Cruzi Dx: (Acute Disease)
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See extracellular flagellated forms in blood smear "C-shped" with kinetoplast at end
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Trypanosoma Cruzi Dx (Chronic Disease)
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Xenodiagnosis (b/c not high enough parasitemia to see it in blood smear)
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Alternate Routes of T. Cruzi Transfer
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- Reduviid feces contaminated food
- Blood transfusion (US blood supply monitored by PCR) - Transplacental |
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T. Cruzi Clinical Manifestations (Acute)
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- Often Asx
- Romanas sign-- painless swollen lesion near eye at site of bite |
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T. Cruzi Clinical Manifestations (Chronic)
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- Dilated Cardiomyopathy (damage due to amastigotes dividing in muscles)
- Destruction of Autonomic ganglia-->megacolon or megaesophagus |
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T. cruzi prevention / treatment
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Bug control, housing improvements
Bendazole--but only 50% effective in chronic disease |
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Trypanosoma Brucei Insect Host
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Tsetse fly
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Trypanosoma Brucei life cycle
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infected fly bites and transmits trypanosome in saliva--multiplies in CSF,lymph, tissues--transmitted back to uninfected fly--multiplies in insect gut and salivary glands
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Trypanosoma Brucei Clinical Syndrome
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- Local nodule at bite site-->ulcer
- post. cervical adenopathy--winterbottom's sign - disseminates to CSF-->lethargy, coma, death |
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Trypanosoma Brucii Diagnosis
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See extracellular form in blood (THERE IS ONLY EXTRACELLULAR FORM)
- kinetoplast is not at then end, as in t.cruzi |
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