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Which parasite can travel up the portal vein and form abscesses in the liver?
- Entamoeba histolytica.
- (heptatomegaly in 50% of cases)
How is entamoeba histolytica spread?
fecal-orally, contaminated food/H20
What are S&S of entamoeba histolytica?
superficial bowel infxn: watery diarrhea, nonspecific GI complaints
- Invasive: abd pain/ bloody diarrhea w/ tenesmus
- sometimes RUQ pain (w/ liver involvement), radiating to rt shoulder
Which cells do entamoeba histolytica lyse?
What diagnostic tests do you use to detect entamoeba histolytica?
- 1)Fecal antigen tests (after 1 wk of sx) or
- 2) PCR
What is the tx for entamoeba histolytica?
- metronidazole (Flagyl) 750 mg TID X 10 days +
- paromycin (aminoglycoside) to rid of cysts
How many entamoeba histolytica cysts need to be ingested to cause disease?
What part of the GI system of Entamoeba infect? Giardia?
- Entamoeba: colon
- Giardia: villi of small intestine
For Entamoeba and Giardia
Cysts vs. trophozoites. Which is infective vs.disease form?
- Cysts: infective (dormant) form
- Trophozoites: active, disease form
Which 3 populations are most prone to entamoeba histolytica infection?
- 1) institutionalized ppl
- 2) promiscous homosexuals
- 3) travelers.
What other condition can amiebiasis be mistaken for?
What do stool smears show for entamoeba histolytica?
some PMNs (but less than seen w/ Shigella)
What is this?
- Giardia Lamblia.
- (Eyes w/ smile).or "bearded human face"
How many cysts are required to cause infection w/ Giardia lamblia
Which parasite is often associated w/ camping/drinking stream water?
What are some symptoms of Giardiasis?
- Diarrhea (sudden onset; initially may be watery) -90%
- Malaise — 85 %
- Foul-smelling and fatty stools (steatorrhea) — 70%
- Abdominal cramps and bloating — 70%
- Flatulence — 75 %
- Nausea — 70 %
- Weight loss — 65 %
- Vomiting/fever < 30%
Which parasite can cause a secondary lactose deficiency?
How long does the diarrhea last from Giardia?
4-6 weeks, so suspect if diarrhea > 2 weeks.
How diagnose Giardiasis?
- 1) Microscopy (Stool smears 3x will find cysts 90% of time)
- 2) ELISA/ immunoflorescence antigen test
What are 2 drugs to treat Giardia?
What species of Cryptosporidium most commonly affects humans?
Which population is most likely to get affected with Cryptosporidium?
Immunocompromised, like AIDS pts.
How do you diagnose Cryptosporidium?
Stool smear: Acid-fast stain.
What is the main S&S of Cryptosporidium?
Chronic water diarrhea often w/ abd cramps.
What is the main drug effective for Cryptosporidium?
Nitazoxanide. (crpyt --> think Night)
What is the string test used to detect?
(Sensitive and cheap, but rarely done in the US)
How is the string test done for Giardia?
- One swallows a gelatin capsule attached to a long
- string. The end of the string remains outside the mouth and is taped to the cheek. The capsule dissolves in the stomach and the string passes into the
- duodenum. The string is left in place for 4-6 hours or overnight. Then it is withdrawn and the end is examined under the microscope for parasites that
- are attached to it.
How is Cryptosporidium spread?
contaminated water, even in swimming pools (it can survive chlorination).
What are the different ways Giardia is spread?
- 1) contaminated water
- 2) person to person in daycare center/institutionalized places (fecal-oral)
- 3) homosexuals (rare)
Why is Entamoeba no longer diagnosed by stool analysis?
Can't be differentiated from 2 other Entamoeba species.
What parasite is the most common one causing brain absesses in immunodeficient pts?
How is it transmitted.
Transmitted by cat feces or eating undercooked meat.
Why is T. gondii difficult for the fetus and immunocompromosied individuals?
Parasite forms vacuoules within cells, the host's immune system does not detect these cysts.
What's another name for Whipworm? How is it acquired?
Trichuris. Acquired by ingestion.
What is this? AKA ___worm. How is it spread?
Tricuris trichiura. (whip worm). Spread fecal-orally.
What are clinical findings of whipworm?
- Most asymptomatic.
- Serious: Fe deficiency, nocturnal stooling.
- loose stools
- Rectal prolapse =often seen
How do you diagnose Trichuruis?
- Fecal smear.
- Tx: MAIN
- Mabendazole & Albendazole --> main ones
- Ivermectin --> not as effective
- Nitazoxanide --> good
How many ppl does Ascaris affect worldwide? How does it access the GI?
Over 1.2 billion. when swallowed, embryos enter venous bloodstream, to lungs, into alveoli, up bronchi & trachea, swallowed.
S&S of Ascaris?
- Most asymptomatic
- If symptomatic: vomting (worms out--mostly in kids 1-5), abdominal pain.
- Heavy: malabsorption, steatthroa, wt loss, if block common bile duct = cholecystitis
What syndrome is associated w/ Ascaris? what is it?
Loeffler's syndrome. It's a condition in which eosinophils accumulates in the lung in response to a parasitic infection.
What type of egg is this? What conditions does this parasite like?
Ascaris lumbricoides. Likes warm & moist.
How do you diagnose Ascaris lumbricoides? What's the down side of the testing?
Stool smear, but eggs don't appear until >40 days of infection. Also if male worms only, no eggs.
What's the treatment for Ascaris? Similar drugs to treating what other worm?
- Mabendazole & Albendazole
- Pyrantel pamoate, nitazoxanide
- (similar to whipworm and pinworm)
What is Enterobius vermicularis AKA? What's the clinical manisfestation?
Pinworm. Nocturnal perianal itching, interfering w/ sleep.
How do you diangose Enterobius?
Cellophane/Scotch tape test.
Which 2 parasite drugs are contraindicated in pregnancy? What is used instead?
- Mabendazole and Abendazole are contraindicated.
- Use pyrantel pamoate instead.
Which 2 nematodes (roundworms) are acquired through the skin?
Strongyloides and Hookworm.
Which parasite is associated with hyperinfection syndrome? What are symptoms?
- GI: Fever. N/V/D, Anorexia, Ab pain.
- Pulm: Dyspnea, Wheezing, Hemoptysis, Cough (Loeffler's)
Which parasite is it possible to autoinfect oneself again?
What are S&S of Strongyloides? What is pathognomonic for Strongyloides?
- Upon entrance:
- inflammation, edema, petechiae, serpiginous or urticarial tracts, and severe pruritus
- Chronic infection: urticaria or pruritis can develop.
- Pathognomonic: larva currens ("running" larva)
What is the Tx for Strongyloidiasis?
Ivermectin w/ Albendazole as an alternative.
How to diagnose Strongyloides?
- Feces or aspiration of duodenal fluid.
- ELISA is good, but can't differentiate past/present infection.
Which population is susceptible to Strongyloides? What meds do you avoid giving?
- Those w/ congenital immunodeficiency, underlying malignancy, malnutrition, alcoholism, hematopoietic stem cell transplantation (HSCT),
- NO corticosteroids or cytotoxic drugs!!
Which parasite is known to be transmitted from stepping in human feces?
Hookworm. (Strongyloides too...)
This is what?
What are the 3 parasites associated w/ Loeffler's syndrome?
- Ascaris, Strongyloides, Hookworm
S&S of hookworm?
- "ground itch" assoc/ w/ local erythema and papular rash at penetration site.
- Cough, wheezing, eosinophilia (Loeffler's)
- Sometimes N/V & flatulence.
TX for hookworm?
- mabendazole (choice), albendazole, pyrantel pamoate
- (ivermectin not effective)
What are the biggest complications w/ hookworm?
- 1) Fe deficiency anemia (adult worms attached to bowel wall and sucking blood) Think hook.
- 2) protein malnutrition
How to diagnose hookworm?
- 1) Stool smear (but only after 2 months infection)
- 2) LABS: High eosinophils (& microcytic anemia, low Albumin)
What parasite produces the condition Visceral larva migrans?
What population does it usually affect?
- Usually affects kids, esp. those having geographous pica.
How is toxacara transmitted?
Ingest egss in animal feces or from undercooked meat of intermediate host (chicken, cattle, swine)
What's the Tx for Toxacara?
- None usually, if really needed Albendazole/Mabendazole
- Steroids often help for severe cases, for inflammation
What are S&S of Toxacara? In the visceral form? Ocular form?
- Visceral form: Hepatosplenomegaly, skin rash
- Ocular: retinitis resembling retinoblastoma
How to diagnose Toxacara?
- Biopsy (but impractical often)
How does one get Trichinosis?
- Usually from consuming cysts in undercooked pork
- (Trichinella spiralis)
What are S&S of trichinella ingestion?
- Gut: mild cramps
- Cysts in muscle: pain, arthralgia,edema, fever, myocarditis
- Classic: subungual splinter hemorrhages, conjunctival and retinal hemorrhages, periorbital edema and chemosis, disturbed vision, and ocular pain
Tx for trichinella?
Mosty none. Mabendazole/albendazole PRN.
Taenia solius causes what condition?
What are clinical S&S of cysticercosis?
CNS: cysts in brain and spinal cord --> seizures
How do you diagnose cysticercosis?
- CT scan,
- x-ray for cysts,
Tx of cysticercosis? What should be screened before initiating steroid therapy?
- Seizure control.
- Albendazole or praziquantel, often w/ steroids.
- Surgery as needed.
Before steroids: Screen for latent TB, strongyloides
TX of parasites:
- Group 1: Entamoeba/ Giardia: Metronidazole (entamoeba also Humanin)
- Group 2: Cryptosporidium: Nitazoxanide
- Group 3: Ascaris/pinworm/hookworm: Mebendazole/ Albendazole
- Group 4: Strongyloides: Ivermectin
Careful of these:
Toxacara vs. Toxoplasma
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