Parasites of GI of Immunocompromised Flashcards
Name 3 intestinal protozoa.
Giardia lamblia-
Entamoeba histolytica-
Crytposporidium
What do giardia lamblia look like? What are their symptoms? What is their lifecycle inside the human body (mechanism)? Transmission? Life cycle? Diagnosis? Treatment?
extracellular flagellated intestinal protozoan
Varies from asymptomatic carriage to severe diarrhea and malabsorption
Most frequent intestinal parasite in U.S.
Attach to brush border of duodenal and jejunal epithelium
Transmitted through ingestion of cysts in contaminated water, food, or fecal-oral route
Life cycle of cysts to trophozoites-which adhere to the intestinal epithelium
Diagnosed by microscopic exam of stool, ELISA of stool sample
Treat with metronidazole
What do Entamoeba Histolytica look like? What are their symptoms? What is their lifecycle inside the human body (mechanism)? Transmission? Life cycle? Diagnosis? Treatment?
extracellular intestinal protozoan
Affects the colon
Cysts are ingested and then trophozoites are released in the small intestine.
Trophozoites adhere to colonic epithelial cells and invade tissue
Can lead to liver abscesses
Transmitted by ingestion of cysts from fecally contaminated food or water
Uncommon in U.S.
Can be asymptomatic, dysentery (amoebic colitis), or extraintestinal disease (liver abscess)
Diagnosed by stool exam, ELISA, serum anti-body titers
Treatment depends on location (luminal- iodoquinol, paromomycin)
What do Cryptosporidium look like? What are their symptoms?
Intracellular Protozoan parasites
Cause self-limited diarrhea in immunocompetent patients
Can cause significant, intractable diarrhea in the immunocompromised-especially those with immunoglobulin deficiency, lymphoid malignancies, or
low CD4 counts associated with HIV.
How is T. cruzi spread? Where does it occur? What are the symptoms?
Trypanosoma cruzi
Spread through the reduviid bug (or kissing bug)
Occurs in Central and South America; few cases in the USA
Causes neuronal damage
Cardiac muscle—cardiac arrhythmias
Colon/esophagus—Megacolon/megaesopahgus- mimics achalasia
List 6 Nematodes.
• Nematodes
– Ascaris lumbricoides
– Strongyloides
– Hookworm
– Trichuris
– Enterobius
– Trichinella
How are Ascaris Lumbricoides acquired? What are the symptoms? How is the diagnosis made? Treatment?
Nematode infection acquired by ingesting eggs
Causes intestinal obstruction and biliary infection.
Diagnosed by visible worm in the stool or eggs observed on stool smear
Adult worms can also be seen on endoscopy.
• Treatment: albendazole
Describe the lifecycle in and outside of the human body, as well as the transmission of strongyloides. What are the symptoms? Diagnosis? Treatment?
Free living organism that doesn’t require a host to replicate
Larvae from soil can penetrate skin, entering the dermis then vasculature.
They circulate within the venous system until they reach the lungs, where they break into the alveoli and ascend the bronchial tree. Worms are then swallowed with bronchial secretions and make their way to the small
intestine. Here they imbed in the jejunal mucosa, mature, and reproduce.
Clinical symptoms include rash, nausea/vomiting, abdominal pain or unexplained GI occult blood loss. Can also cause colitis and mimic inflammatory bowel disease.
Diagnosed by ELISA for IgG against the organism.
• Treat with ivermectin
What causes hookworm? How are they transmitted? What is their lifecycle in the human? Symptoms? Treatment?
- Ancylostoma duodenale
- Necator americanus
- Infect 20% of the world’s population
- Cause infection much like Strongyloides, penetrating the skin
- Worms can also be directly ingested through contaminated food
• Adult worms feed on intestinal epithelial cells and red
blood cells
- Cause iron deficiency anemia and eosinophilia
- Some species infect cats and dogs
- Treat with albendazole or mebendazole
What is trichuris? Symptoms? Size?
Trichuris (Whipworm)
• Infection can be
asymptomatic or cause
diarrhea
• Infection with large
numbers can cause
rectal prolapse in
• Worms can be up to 3
cm in size
What is enterobius? Life cycle in humans? What are the symptoms? Diagnosis?
Pinworm
• Adult worms live in the colon
• At night worms migrate to the anus and release
thousands of fertilized eggs onto the perianal skin
• Within hours eggs hatch into larvae and are
infectious
- Hosts generally asymptomatic.
- Can cause pruritis ani, restless sleeping
- Can cause vulvovaginitis in girls
“scotch tape test”
What is the transmission of trichinella? Symptoms? Life cycle in humans?
- Infection occurs through ingestion of undercooked meat (often pork)
- Causes gastroenteritis, fever, muscle pain, eosinophilia
- After larvae hatch, they travel via the bloodstream to other organs
• Larvae develop in striated muscle cells, and
can persist there for years
List 2 cestodes.
• Cestodes
– Diphyllobothrium
– Taenia saginata and solium
What is Diphyllobothryium? What does it look like? Symptoms?
- Fish tapeworm
- Largest of the human parasites
- Can reach up to 40 feet!
- Absorbs cobalamin and can cause vitamin B12
deficiency over time.
What are taenia saginata and taenia solium? What is their lifecycle? What are their common symptoms? Which is more likely to have symptoms? What are the symptoms unique to T. solium? How are they diagnosed? Treated?
- Taenia saginata (beef tapeworm)
- Taenia solium (pork tapeworm)
- 80 million people worldwide colonized
Eggs in feces in soil. Pigs and cows eat the feces. They hatch, penetrate intestinal wall, and circulate to musculature. Cysticerci form in the muscles. Humans ingest them. The scolex attach in human intestine. Adults form in the small intestine.
- Usually none
- Digestive problems- abdominal pain, loss of appetite, weight loss, dyspepsia
- Symptoms more likely with T. saginata because it is larger (up to 10 m).
- Visible symptom of passing proglottids in feces.
- T. solium infection can result in human cysticercosis.
- Caused by larval cysts
- Infect brain, muscle, other tissue
- Major cause of adult seizures in underdeveloped countries
