Infectious Disease (Block 6): Gastrointestinal Protozoa

Front 1

1. number one parasitic infection causing death
2. what are the majority etiologies of neglected tropical dz's (NTDs)?

Back 1

malaria; parasites!

Front 2

differentiate b/w definitive, intermediate, reservoir, and incidental HOSTS.

Back 2

o Definitive – where parasite undergoes sexual reproduction or reaches sexual maturity
o Intermediate – where asexual stage develops
o Reservoir – harbors a parasite harmful for other animals
o Incidental – type of host that is accidentally infected & not required for parasite survival

Front 3

protozoa are ___ celled organisms, that multiply SEXUALLY/ASEXUALLY in _____. what are the 2 main types of protozoa?

Back 3

single; asexually; humans

2 types: intestinal protozoa & blood/tissue protozoa

Front 4

Are protozoa usually associated with eosinophilia? what about helminths? what's the exception?

Back 4

protozoa not associated with eosinophilia (EXCEPT for Isospira!!)

helminths (worms) are associated with eosinophilia...that makes sense right?

Front 5

what three protozoans do you treat with metronidazole?

Back 5

GET on the Metro!!

Giardia, Entamoeba histolytica, Trichomonas

Front 6

who is at risk for giardia? how is transmitted/pathogenesis?

Back 6

campers, children in daycare centers, homosexuals.

transmitted by fecal-oral (contaminated hands/fomites) or drinking contiminated water. ingest cyst, giardia converts to trophozoite form, coats small intestines and interfers with fat absorption.

Front 7

incubation of giardia. how would a pt wiht giardia show up?

Back 7

incubation= 5-6 days
pt would have large volume, bulky FOWL smelling & watery diarrhea (may have nausea/vomiting) that could last 1-3 weeks

Front 8

how do you dx giardia?

Back 8

stool antigen test (ELISA)

Front 9

is giardia INTRACELLULAR or EXTRACELLULAR small intestine parasite?

name the intracellular small intestine parasites.

what is the most common intracellular small intestine parasite ?

Back 9

extracellular

Out of cryptosporidium, microsporidium, isospora, cyclospora, CRYPTOSPORIDIUM is the most common (has low infectious dose and oocytes doesn't need maturation process)

Front 10

where woudl cryptosporidium be found and how does it transmit/pathogeneiss?

Back 10

waterparks, swimming pools, rivers, lakes, daycare, hospitals

transmission:
-fecal-oral
- contaminated food/water

- oocytes are ingested and infect/destroy enterocytes leading to watery diarrhea and abdominal pain

Front 11

clinical manifestation/duration of cryptosporidium. what's the difference in immunocompetent vs immunocompromised patients?

Back 11

- watery diarrhea for 1-2 weeks
that's usually self-limited in immunocompent pts
- in immunocompromised (esp HIV pts), this organism causes chronic diarrhea that is life thretening (if CD4<50, pt can get biliary tract disease)

Front 12

how do you Dx for cryptosporidium? how does this compare to the other 2 porotozoans that require this stain?

Back 12

-acid fast stain (look for oocysts)
-stool antigen test (ELISA)

other 2 that use acid fast stain are isospora and cyclospora. in order of size on the stain, its: ISOSPORA > cyclospora > cryptosporidium

Front 13

Tx of cryptospordiium (immunocompetne vs immunocompromised)?

Back 13

healthy pt = nitazoxamide

HIV pt = HAART

Front 14

what type of pt do you almost only find microsporidium? what is the clinical manifestations and how do you dx it?

Back 14

AIDS patients; chronic diarrhea/biliary tract dz

Dx: non-specific fluorescent stain

Front 15

where is isospora most commonly found? who is at particularly high risk?

Back 15

S. America, Africa (uncommon in US)

immunocompromised pts are at high risk

Front 16

what does isospora/cyclospora both cause? how are they transmitted?how do you Dx and Tx it?

Back 16

watery diarrhea (that if left untreated can cause persistent diarrhea)

transmission: fecal-oral

Dx: acid fast stain

Tx: bactrim (TMP/SMX)

Front 17

what's the difference bw isospora and cyclospora?

Back 17

only isospora causes eosinophilai (everything else about the two parasties are generally the same)

Front 18

name the parasite that causes disease in the large intestines. what parasitic stage is ingested and what parastici stage causes dz? what's the pathogenesis?

Back 18

entamoeba histolytica

cysts are infective; trophozoites cause dz by invading intestinal mucosa casuing erosion ==> colitis & possibly dysentery (bloody diarrhea). they can also enter bloodstream and cause hepatic abscess or lung abscess.

Front 19

what are the clinical manifestations of entamoeba histolytica?

Back 19

MOST CASES CAUSE ACUTE, SELF-LIMITED WATERY DIARRHEA!!

intestinal:
- colitis (ulceration and possible dysentery)
- may cause chronic granulomatous lesion (ameboma= formation of annular colonic granulation, which results in a large local lesion of the bowel)

hepatic:
- cystic mass in liver with RUQ pain
- often presetns w/o diarrhea/fever

Front 20

Dx of e. histolytica

Back 20

intestinal = stool microscopy, then differntiate with stool ELISA test (aspirate the RIM of the abscess)

hepatic = utlrasound/CT
- serology only useful for travelers

Front 21

pathogenesis/clinical manifestations of trichomonas vaginalis. how do you Dx it?

Back 21

pathogenesis:
- infects vaginal mucosa and urethra
- transmitted by sexual contact

clinic:
- women get VAGINITIS w/ purulent discharge, "strawberry cervix"
- men usually asymptomatic (could have urethritis)

Dx: direct microscopy of discharge

Front 22

most common microsporidial protozoan in AIDS patients

Back 22

E. bieneusi