Parasitic infections of the GI tract Flashcards
what are protozoa and what are their four classes? how do they reproduce?
-eukaryotes and have four classes based on moltility
1) ameba-pseudopodia
2) flagellates- flagella
3) sporozoans- gliding
4) ciliates- cila
reproduce asexually via binary fission or SOMETIMES asexually via schizogony and sexually via sporogoy
can make -cyst forms can protect them from the environment and aid in transmission
what causes Amebiasis? what are the two forms of the amoeba and how are they different? how does the amoeba infect?
- Amebiasis caused by entamoeba histolytica (in history, there has been a lot of racial biases)
- 2- trophozoic form and cyst form
- trophozoic form, when ingested is killed by stomach acids but cyst form is resilient and can cause 1 of 2 things:
1) can infect the GI tract (colon) and multiply causing dysentery
2) can invade the wall of the colon and multiply to infect extra-intestinal organs such as lungs, liver (have flask shaped ulcers that are characteristic) etc
how do you get Amebiasis? how long after ingestion do you see symptoms?
get entamoeba histolytica via ingestion; 1 wk
what’s important to note about aymptomatic vs symptomatic pt with entamoeba histolytica (Amebiasis)
-asymptomatic people are spreading cyst form while symptomatic people are spreading trophozoic form of the bacteria so asymptomatic people are the virulent ones
what’s different between parasitic dysentery and bacterial dysentery? where is the exception?
-parasitic dysentery does not come along with FEVER!!!
(all symptomatic parasite-infected pt will have blood in stool)
-exception- when the cyst form invades the lumen of the GI tract to enter the blood stream, it causes inflammation and fever
diagnosis and prevention of entamoeba histolytica (amebiasis)
diagnosis- stool sample and antigen detection- (eggs and paracytes)- can often see lysed RBCs in sample
prevention- sanitation/hygiene
in terms of stool, what does poop look like if pt has trophozoic vs cyst forms of entamoeba histolytica
trophozoic- dysentery, watery stool
cyst- formed stool
what is giardiasis and what is it caused by? what are the forms it can come in and what are some characteristics of each?
- it is diarrhea, foul smelling stool, bloating, greasy stool, ab cramps, nausea, NO FEVER, NO BLOOD
- caused by giardia
- parasite that has two forms- cyst (that infects and is resilient) and trophozoic form
- trophozoic form looks like a sting ray with two eyes and flagellates whereas the cyst form looks like an oval with 2 eyes
how does giardia infect?
- it enters via fecal oral route and the cyst form enters the duodenum and multiplies allowing the cyst form to ATTACH to the mucosa of the duodenum (DOES NOT INVADE like entamoeba histolytica)
- because it attaches and doesn’t invade, you get diarrhea and not dysentery
who mostly gets giardiasis and when do adults get it?
- kids
- adults get it mostly during the summer when they are in recreational areas like pools and lakes
what is important to note about asymptomatic and symptomatic people with giardia?
-asymptomatic have the cyst form that is transmissible
diagnosis and prevention of giardiasis?
diagnosis- observation of cysts in formed stools or trophozites in diarrheal stools
prevention- sanitation and hygiene with water treatment
Balantidiasis
caused by
how does the disease work
- caused by balantidium coli
- has trophozoic and cyst form
- cyst form has CILIA that acts much like enamoeba histolytica where it invades wall of colon and multiplies and either returns to the lumen causing dysentery
what is unique about balantidium coli?
where does it derive from
- it is the only ciliate that infects man
- pigs- so people who work with them can get it
symptoms of blantidiasis?
- generally asymptomatic
- chronic infection can cause diarrhea to constipation and back
- acute disease diarrhea with blood and mucus (dysentery)
cryptosporidiosis
parasite
how does parasite infect?
- caused by cryptosporidium parvum
-infects via contaminated water (oral/fecal) and are SPORAZOANS that glide to move
-when ingested, attaches to surface of intestinal epithelium and reproduces via SEXUAL REPRODUCTION TO DEVELOP A FERTILIZED OOCYST
-mature oocyst shed in feces
(mnemonic is that crypto-SPOR-idium has spore in it so it says sexual reproduction and also it’s a sporozoan that glides)
what population do we worry about when it comes to cryptosporidiosis?
-HIV population -when CD4 is down, they start treating pt with prophylaxis for c. parvum because it is so common
crypotsporidium parvum transmission-
symptoms-
prevention-
Diagnosis
transmission- oral/fecal-ingestion of oocytes, peaks in early summer to fall (pools?)
symptoms-profuse watery diarrhea, cramping, fatigue, weight loss, NO BLOOD
prevention-self limiting (1-2wks) but can be prolonged or fatal in immunocompromised, sanitation and water treatment
diagnosis- ACID FAST OOCYST IN STOOL
Isospora belli
- ingest oocyst (because sexual reproduction spores) and then it is replicated in intestinal epithelium and makes another oocyst that’s passed into the feces
- NOTE- THE OOCYST IS OVAL SHAPED
what individuals are most likely to get isospora beli? symptoms?
- immunocompromised individuals
- diarrhea, fever, weight loss
- severe- watery diarrhea, malabsorption, electrolyte imbalance, death
cyclospora
- oocyst sporalation in environment and we ingest oocysts via raspberries, basil water
- shed oocysts
how do we identify cyclospora? what can it be confused with? what distinguishes the two?
via acid fast staining where it stains pink just like cryptosporidium parvum
-distinguishing factor- fluorescent spores under UV light = cyclospora
symptoms of cyclospora
-watery diarrhea, cramping, fatigue, weight loss
microsporidiosis
- caused by microsporidia spp.
- primitive eukaryotes that infect via ingestion of spores
- can infect the intestines causing chronic diarrhea and anorexia (10-20 stools a day) and can disseminate to rest of body
