36 - Parasitic Infections of the GI Tract Flashcards
What are protozoa?
- A diverse group of mostly motile unicellular eukaryotic organism
There are four different classes of protozoa. What are they?
- Ameba-pseudopodia
- Flagellates-flagella
- Sporozoans-gliding
- Ciliates-cilia
Most protozoa reproduce ________ by _________
Most protozoa reproduce asexually via binary fission
Why is this asexual reproduction clinically relevant?
- This is important because if you’re infected by just one small parasite, it will replicate and make you very ill
- This allows them to have a very low infectious dose to cause disease
What type of protozoa can reproduce asexually AND sexually?
Sporozoans
What are the names of their sexual and asexual reproduction types?
Schizogony = asexual Sporogoy = sexual
What does the ability to reproduce sexually AND asexually allow for?
Allows these parasites to exist in the environment
- Dry
- Head
- GI tract pH
Very stable through all of this
How are sporozoans transmitted?
Fecal-oral route
What do many potozoans produce which protects them from the environment and aids in transmission?
Cysts
What is amebiasis-entamoeba histolytica?
- An important ameba that only causes a few thousand cases of entamoeba (disease) per year
What is an important feature of the hystolytica form?
It is the stable form
- Stable in the environment
- Protected from GI tract
- Able to do fecal-oral transmission
What is the mode of ingestion?
Ingestion of cysts via the fecal-oral route
What are the symptoms of hystolytica?
Bloody, mucous diarrhea
What intestinal disease does hystolytica cause??
- Gastrointestinal distress
What percent of symptomatic patients will present with visible or microscopic blood in their stool?
95-100%
What is a major sign of hystolytical?
BLOOD IN THE STOOL (dysentery)
What is common in bacterial dysentery that is rare in hystolytica?
Fever
So what key things do you need to remember about hystolytica?
Bloody stool with NO fever
What happens when hystolytica leads to an invasive disease?
Penetration of the intestinal wall by tophozoites
What type of lesions do histolytica form?
Flask shaped lesions
How does histolytica spread throughout the body?
Spread via the blood stream
What will a systemic infection of histolytica cause?
- Liver abscess
- Abdominal pain
- Fever
- WBC
How do you diagnose histolytica?
- Stool examination
- Antigen detection (intestinal)
What is the rapid test for histolytica?
- A dip stick test, which looks for the antigen
- This type is becoming more common
When would you use a biopsy and serology (extra-intestinal) in order to test for
If you think they have an abscess
How do you control and prevent histolytica?
- Sanitation
- Hygiene
- Proper waste water treatment
This is easy in the US… Not so easy in developing countries
What disease is caused by Giardia lamblia?
Giardiasis
How many cases do we see each year in the US?
20,000 to 30,000
There are two forms. What are they?
- Flagellated form
- Cyst form
Does the cyst form have any flagella?
No
Is giardia typically deadly?
No, usually no deaths due to giardia
Is giardia seen more commonly in males or females?
Equal
What population is giardia seen most commonly in?
Young children
Due to the fecal-oral route of transmission
What activities is giardia associated with?
Bathtub, swimming pool, lake water
Not food transmission very commonly
What time of the year does giardia peak?
Summer months - swimming
What is the pathogenesis of giardia?
Flagellated form has “plungers” that attach to the intestinal mucosa – your entire GI route can be coated with these things
Is giardia invasive?
NO
Do you see a fever with giardia?
No