GI/urinary parasites Flashcards
Giardia- morphology
Trophozoite, flagellated, with ventral sucking discs
Giardia- transmission
Fecal-oral transmission; travelers/campers ingest cysts from contaminated water in endemic areas
Giardia- presentation
Foul-smelling steatorrhea, weight loss/malabsorption
Which vitamins may become deficient due to giardia?
A, D, E, K (bleeding!), due to fat malabsorption
Giardia- diagnosis
- Trophozoites in stool O&P (cysts may also be visible)
- ELISA stool antigen test
Giardia- treatment
Metronidazole
Entamoeba histolytica- presentation
- Flask-shaped ulcerations in colon (intestinal amebiasis)
- Inflammatory diarrhea
- Amoebic liver abscess (right lobe; RUQ pain; “anchovy paste” consistency)
Entamoeba histolytica- diagnosis
- Trophozoites containing endocytosed RBCs/cysts on stool O&P
- ELISA antigen test of stool/serum
- Serology for anti-Entamoeba antibodies
- Flash-shaped ulcerations on intestinal biopsy
Entamoeba histolytica- treatment
Metronidazole
Entamoeba histolytica- lifecycle
Cysts are ingested (fecal-oral via contaminated water, eating ass); trophozoites invade colon, enter the portal system, and spread to the liver
Entamoeba histolytica- treatment
- Metronidazole
- Luminal agents (Paramycin, iodoquinol)
Is surgery necessary for liver masses in Entamoeba histolytica?
No
Is surgery necessary for liver masses in Echinococcus?
Yes
Is surgery necessary for liver masses in Echinococcus?
Yes
Cryptosporidium- morphology
Unicellular, partially acid-fast organisms
Cryptosporidium- transmission
Immunocompromised/AIDS patients, people who swim in dirty water, campers, people who work with animals; fecal-oral ingestion of oocysts; resistant to chlorination
Cryptosporidium- presentation
Severe diarrhea in AIDS/immunocompromised patients; mild watery diarrhea in immunocompetent individuals; usually affects small intestine but may cause colitis
Why does Cryptosoridium cyst appear multifaceted?
Bundle of four sporozoites
Cryptosporidium- treatment
- Nitazoxanide
- Spiramycin (macrolide; not approved in USA)
Schistosoma mansoni- morphology
- Trematode
- Large, lateral spine
Schistosoma japonicum- morphology
- Trematode
- Small spine
Schistosoma hematobium- morphology
- Trematode
- Large, terminal spine
Schistosoma mansoni- presentation
- Swimmer’s itch where larvae penetrate the skin
- Resides in mesenteric veins
- Portal hypertension, leading to GI hemorrhage, abdominal pain, and jaundice/cirrhosis
Schistosoma japonicum- presentation
- Swimmer’s itch where larvae penetrate the skin
- Resides in mesenteric veins
- Portal hypertension, leading to GI hemorrhage, abdominal pain, and jaundice/cirrhosis
Schistosoma hematobium- presentation
- Swimmer’s itch where larvae penetrate the skin
- Resides in the bladder
- Hematuria
- Bladder cancer
What is the intermediate host of Schistosoma?
Snails
Schistosoma- treatment
Praziquantel
Schistosoma- treatment
Praziquantel
Clonorchis sinensis- morphology
- Trematode
- Operculated eggs
Clonorchis sinensis- transmission
Larvae from snail hosts are transferred to fish. Humans ingest cysted larvae in uncooked fish.
Clonorchis sinensis- treatment
Praziquantel
Clonorchis sinensis- diagnosis
Operculated eggs on stool O&P
What is the intermediate host of Clonorchis sinensis?
Snails
Clonorchis sinensis- presentation
“Liver fluke”;Reside in biliary tract, causing biliary tract fibrosis, pigmented gallstones, and cholangiocarcinoma
Paragonimus westermani- type of parasite
Trematode
Paragonimus westermani- presentation
“Lung fluke”; causing chronic cough with bloody sputum
Paragonimus westermani- transmission
Consumption of raw/undercooked crab meat with larvae
Paragonimus westermani
Praziquantel
Taenia solium- transmission
Intermediate host is pig
Taenia saginata- transmission
Intermediate host is cattle
Taenia solium- diagnosis
Cestode with proglottid head on stool O&P
Taenia saginata-
Cestode
Taenia- presentation
- Taeniasis from ingesting cysts (GI problems, malabsorption)
- Neurocysticercosis from ingestion of eggs (seizures and hydrocephalus)
Taenia- treatment
- Praziquantel for taeniasis
- Praziquantel + albendazole for neurocysticercosis
Diphyllobothrium latum- diagnosis
Cestode with proglottid segments on stool O&P
Diphyllobothrium latum- presentation
- “Fish tapeworm”; resides in small intestine and causes diarrhea, associated with B12 deficiency and magaloblastic anemia
- Longest tapeworm
Diphyllobothrium latum- treatment
Praziquantel or niclosamide
Ecchinococcus granulosus- transmission
- Cestode
- Sheep are intermediate hosts.
- Dogs are definitive hosts.
- Humans are incidental hosts from ingestion of eggs (fecal-oral route)
Ecchinococcus granulosus- treatment
Surgical removal of cysts, with prior injection of ethanol/hypertonic saline into cysts to kill cells and prevent anaphylaxis
Ecchinococcus granulosus- presentation
- Hydatid cysts in the liver (looks like slow growing tumor; eggshell calcifications on CT)
- Anaphylaxis and acute abdomen if hydatid cysts rupture
- Hooks in sputum if cysts rupture in lungs
- Eosinophilia may be observed (all helminths)
Enterobius vermicularis- diagnosis
Nematode; Scotch tape shows eggs deposited at night
Enterobius vermicularis- transmission
Female worms migrate to anus at night to lay eggs; spread by fecal-oral route (scratching itchy anus causes reinfection)
Enterobius vermicularis- presentation
Itchy anus
Ecchinococcus granulosus- treatment
Pyrantel pamoate or albendazole
Acyclostoma duodenale- transmission
Common in southern US; larvae penetrate skin of sole of feet and go to lungs, ascend bronchial tree, are coughed and swallowed, and mature into adults in the small intestine
Necator americanus- transmission
Common in southern US; larvae penetrate skin of sole of feet and go to lungs, ascend bronchial tree, are coughed and swallowed, and mature into adults in the small intestine
Acyclostoma duodenale- presentation
Iron deficiency anemia
Acyclostoma duodenale- diagnosis
Eggs in stool, high eosinophil count
Necator americanus- presentation
Iron deficiency anemia
Necator americanus- diagnosis
Eggs in stool, high eosinophil count
Necator americanus- treatment
Pyrantel pamoate (choice) or albendazole
Acyclostoma duodenale-
Pyrantel pamoate (choice) or albendazole
Ascaris lumbricoides- transmission
Eggs in contaminated food/water; eggs hatch in small intestine, and larvae migrate into bloodstream into the lungs, where they ascend the bronchial tree, are coughed and swallowed, and mature into adults in the small intestine
Ascaris lumbricoides- presentation
- Respiratory symptoms
- GI obstruction (especially at ileocecal valve)
Ascaris lumbricoides- diagnosis
- Eggs in stool
- Eosinophilia
Ascaris lumbricoides- treatment
Albendazole
Albendazole- MOA
Cause microtubule dysfunction and immobilize worms
What complication can happen with albendazole?
Intestinal obstruction due to immotile worms
Alternative to albendazole in pregnant women
Pyrantel pamoate
Strongyloides stercoralis- diagnosis
- Larvae in the stool (eggs do not exit!)
- Eosinophilia
Strongyloides stercoralis- transmission
Larvae penetrate skin of sole of feet and go to lungs, ascend bronchial tree, are coughed and swallowed, and mature into adults in the small intestine. Autoinfection by laying eggs in the intestinal tract, which then penetrate the wall and enter the bloodstream.
Strongyloides stercoralis- treatment
- Albendazole
- Ivermectin
Trichinella spiralis- type of parasite
Nematode (intestinal)
Trichinella spiralis- presentation
Fever, vomiting, and periorbital edema, severe myalgias (larvae form cysts within striated muscle)
Trichinella spiralis- transmission
Ingestion of cysts from undercooked meat (especially pork or bear)
Trichinella spiralis- treatment
Albendazole
