Parasites Flashcards
what is the mode of transportation for Entamoeba histolytica?
fecal oral/ oral anal
Clinical presentation of Entamoeba histolytica
• Amebic colitis / Amebic dysentery (invasive, so bloody diarrhea with blood + PMNs)
• Trophozoite (vegetative form)→ disintegrates to form a cyst (infectious form) → stomach acid breaks it apart →parasite enters the colon → multiplies, vegetates and invades
• Amebic liver abscess
Flask-shaped ulcers →
Diagnosis of Entamoeba
serology and/or trophozoites or cysts (multi-nucleated) in the stool
Treatment of Entamoeba
- Noninvasive disease: paromomycin
* Invasive disease: metronidazole
Mode of transportation: Giardia lamblia
Contaminated water
• Fecal-oral transmission
• Sylvatic distribution in streams, lake
• * Beaver fever → exists as a commensal in beavers
Clinical presentation: Giardia lamblia
- Foul-smelling stools, cramping, explosive watery diarrhea
- Malabsorption syndrome: steatorrhea → fat in the stool
- Malodorous, mushy, greasy stool
Diagnosis: Giardia lamblia
trophozoites or cysts in stool; pear-shaped; 2 nuclei the same
Treatment: Giardia lamblia
metronidazole
Mode of transmission: Balantidium coli
fecal oral; Reservoir is pigs → boar hunter, slaughterer, farmer
Clinical presentation: Balantidium coli
bloody diarrhea;
Treatment: Balantidium coli
Tetracylcine
Mode of transmission: Isospora belli
contaminated water/food. oral/anal
AIDS patients susceptible
Clinical presentation: Isosopra belli
Mimics giardiasis with malabsorption
loose-foul smelling stools
chronic weight-loss, anorexia, malaise and fatigue can be seen
Diagnosis: Isospora belli
- Stains acid-fast
* Iodine-stained stool smears used in diagnosis
Treatment: Isospora belli
• TMP-SMX
Mode of transmission: cryptosporidium
- Water-borne
- Oocyst is stable and able to resist chlorination → will be found in bodies of water, including residential or community pools
- AIDS patients are susceptible
Clinical Presentation: cryptosporidium
- “Crypto”: frequent, explosive, watery diarrhea → dehydration and vomiting
- In AIDS patients, > 50 stools/day that can last for month to years
Diagnosis: cryptosporidium
cysts on stains acid-fast
Treatment: crptosporidium
prevention; Replace fluid and electrolytes
Mode of transmission: cyclospora cayetanensis
- Acquired from contaminated water or food
- Raspberries in Guatemala
- Basil in Mexico
Clinical presentation: cyclospora cayetanensis
- Similar to “Crypto”
* Explosive, watery diarrhea
Diagnosis: cyclospora cayentanensis
Stains acid-fast
Fluoresces blue under UV light
Treatment: cyclospora cayen
• TMP-SMX
Mode of transmission: Enterobius vermicularis (pinworm)
- Endemic in the U.S., especially in children
- Fecal-oral transmission
- Acquired by ingestion of sticky eggs and autoinfection
Clinical Presentation: Enterobius vermicularis
- Intense perianal nocturnal itching
* Females lay their eggs around the anus, which are removed and transmitted as the children scratch their “botitos”
Diagnosis: Enterobius vermicularis
Cellophane tape used for diagnosis
Treatment: Enterobius vermicularis
- Pyrantel pamoate (OTC)
* Mebendazole or albendazole (Treat whole family)
Mode of transmission: Ascaris lumbricoides (roundworm)
- Fecal-oral transmission
* Acquired from food or water as ingested eggs
Clinical Presentation: Ascaris lumbricoides
Early phase: lungs • Coughed up and swallowed into GI tract Late phase: GI tract • Bolus obstructs the bowel • Can migrate to the liver
Diagnosis: Ascaris lumbricoides
- Knobby-coated, oval-shaped egg
* Bile-stained
Treatment: Ascaris lumbricoides
• Albendazole
Mode of transmission: Trichuris trichiura (whipworm)
Fecal-oral
Clinical presentation: -Trichuris trichiura (whipworm)
- Watery to bloody diarrhea → if severe, rectal prolapse
- Trichuris dysentery syndrome in infants
- Bloody, mucoid diarrhea
- Anemia
- Growth retardation
Diagnosis: Trichuris trichiura
Barrel-shaped egg with plugs at the ends
Treatment: Trichuris trichiura
• Mebendazole
Mode of transmission: Necator americanus
fecal oral; Generally acquired by stepping on larval worm in sandy soil
Clinical presentaton: Necator americanus
Early phase
• Larval migration from foot → lungs
• Itching, localized maculopapular eruption on the foot
Late phase
• Coughed up from the lung → swallowed into GI tract
• Nausea, vomiting, diarrhea
• Microcytic, hypochromatic anemia
Diagnosis: Necator americanus
Early phase → larval migration
• Eosinophilia, normal stool
• Patchy infiltrate on chest X-ray and productive sputum
Late phase
• Non bile-stained, segmented, thin shelled eggs in stool
Treatment: Necator americanus
- Albendazole; second line includes mebendazole or thiabendazole for migrating larvae
- Iron therapy for anemia; if severe, transfusion is necessary
Mode of transmission: Strongyloides stercoralis (threadworm)
Fecal oral
Clinical presentation: Strongyloides stercoralis
- Vomiting, diarrhea (bloody), malabsorption
- Hyperinfection syndrome
- Larvae spread throughout body → meningitis, secondary bacteremia
Diagnosis: Strongyloides stercoralis
- Microscopy of larval worms in the stool is used for diagnosis
- Similar to hookworm, but the eggs hatching in intestine causing an autoinfection
Treatment: Strongyloides stercoralis
vermectin
Mode of transmission: Trichinella spiralis
- Acquired from larvae ingested in undercooked meat
- Pork, bear, fox, walrus meat
- Larvae found in undercooked bear meat or infected worm
Clinical presentation: Trichinella spiralis
- Fever, myalgias, eosinophilia, periorbital edema
* Lethal when heart, brain, or lungs are infected
Treatment: Trichinella spiralis
- Bed rest, antipyretics and analgesics
* Albendazole for adult worms
Mode of transmission: Fasciolopsis buski (fluke)
• ALL flukes have a clam or snail intermediate host, which is infected by free-swimming cercaria
• Fecal-oral transmission, with the metacercariae being injested (except for schistosomes)
*water chestnuts
o Seen most often in China, Vietnam, Thailand and India
Clinical presentation: Fasciolopsis buski
o Diarrhea alternating with constipation
o Anorexia, nausea, vomiting
o Malabsporption syndrome (like Giardia and Isospora)
Diagnosis: Fasciolopsis buski
o Large, bile-stained, operculated eggs in stool
• Flat, leaf-shaped worm
• Larger than nematodes
Treatment: Fasciolopsis buskhi
o Praziquantel
Mode of transmission: Fasciola hepatica (fluke)
fecal / oral
ALL flukes have a clam or snail intermediate host, which is infected by free-swimming cercaria
• Acquired from water cress (sheep liver)
Clinical presentation: Fasciola hepatica
o Hepatitis, biliary obstruction
Diagnosis: Fasciola hepatica
o Eggs in stool used for diagnosis
Treatment: Fasciola hepatica
o Bithionol
Mode of transmission: C. sinesis
fecal oral
• Acquired from raw freshwater fish
chinese liver
Treatment: C. sinesis
o Praziquantel
Mode of transmission: S. mansoni
reservoir hosts, specifically primates and rodents
Clinical presentation: S. mansoni
o Bloody diarrhea due to “clay pipestem fibrosis”
• Fibrous tissue surrounds portal vein in liver
Diagnosis: S. mansoni
o Large eggs have * lateral spine (terminal spines are associated with Schistosoma hemaetobium)
Treatment: S. mansoni
o Praziquantel
Mode of transmission: Taenia solium (tapeworm)
eating undercooked pork; not in U.S
Clinical presentation: Taenia solium
Abdominal pain, diarrhea, ingestion
Cysticercosis (ingestion of eggs) only caused by T. solium
Autoinfection
Larvae disseminate → calcify in tissue → neurocysticercosis, muscle and connective tissue
Diagnosis: Taenia solium
- Flat and ribbon like
- Head (scolex) has cup-shaped sucker and hook
- Proglottids = segmented bodies
- Can use CT or MRI can be used for calcified cyst identification
Treatment: Taenia solium
• Praziquantel
Mode of transmission: Diphyllobothrium latum
• Acquired from undercooked freshwater fish, raw fish, and pickled fish (“Gefilte fish”)
Clinical presentation: Diphyllobothrium latum
• Depletion of vitamin B12
Treatment: Diphyllobothrium latum
• Niclosamide
Mode of transmission: Taenia saginata
- Acquired from undercooked beef
* In the U.S., and seen worldwide
Mode of transmission: Echinococcus
• Sheep-herders are particularly susceptible → host are in dogs and foxes
Clinical presentation: Echinococcus
• Hydatid cyst disease within the liver and the lung
Treatment: Echinococcus
surgery
