What are the 4 classes of protozoa?
And their distinguishing feature?

Amoeba- pseudopodia
Flagellates- flagella
Sporozoans- gliding
Ciliates- cilia

What are the classes based on?

based on motility

What is the reproduction scheme of most?

binary fission

What is the reproduction of some?

Some sporozoans can do asexual via Schizogony, and/or asexual via Sporogoy

What is the protective/infectious form of protozoa?

protects from env and helps in transmission

Overall, how do cysts get back to environment?

we usually ingest in cyst form, people poop them out

What are the 5 protozoa we are going to talk about here?

Entamoeba histolytica, Giardia lamblia, Cyclospora, Isospora belli, and Cryptosporidium parvum


What disease does Entamoeba histolytica cause?


What is the infectious form?


How is it transmitted?


trophozoites will not survive in the env. or gastric acidity, so they are not infectious

Pathology? Where will it multiply? Is it invasive?

Cysts hatch in GI goes to either colon or circulatory multiplies in colon; INVASIVE

What is the claim to fame?

only ameoba that causes disease

other non-pathogenic species confused for E. histolytica.
E. dispar often responsible for asymptomatic infections

What are the secondary effects**** of the pathogenesis of Entamoeba histolytica?

lysis RBC's and forms brain and liver abcesses


GI distress

All symptomatic pts have will present with visible or microscopic blood in their stool (dysntary)

NO fever! this is a way you can distingiush ameobic dysentary from other dysenteries

Symptomatic vs. Asymptomatic? and passing on disease?

Symptomatics have the Tropho-fom but have a harder time passing the disease on

Asymptomatics have cyst form but pass it on easily

Life cycle?

lacks a sexual stage
infectious cyst form and an invasive trophozoite form

cyst can survive in env for weeks, enters humans, motile trophs are released from cysts in the small intestine and go to large: then can invade host tissues (symptomatic) or live in the lumen of LG Intestine without invasion (asymptomatic) or encyst and be shed from host

What is the shape of Entamoeba histolytica penetration lesion into the intestinal wall?

FLASK shaped

When is the only time we see fever with Entamoeba histolytica?

When they get through intestine, into circ., then into liver and make abscesses
get fever and abdominal pain, and WBC increased


Stool sample, observational
see cysts or trophozoites
biobsy and serology (extra-intestinal) reacting to antigens of the ameoba

Control Prevention?


When do we see watery stool: with more trophs or more cysts?

more trophs = watery

more cysts = formed



What are the 2 forms of Giardia lamblia?

1: flagellated looks like a sting ray w/ 2 eyes

2: Cyst normal cyst form

Path? Where will they settle? How is this done?

Ingested as cyst excyst in duodenum multiplies by binary fission on mucosa of duodenum--> NO INVASION Adheres to mucosa in intestines using a suction disk on the front of their body --> in feces

Age group of target? Why?

VERY young (b/c kids can be gross); 25-40 y. olds b/c of the recreational sports/being outside a lot



peaks in summer to late fall
can be animal reservoirs

symptomatic: pass trophozoites
asymptomatic: pass more cysts

What harbors Giardia lamblia a LOT?

water sources

Where can outbreaks (locations)?

Day care centers and workers there; recreation spots

Sx? (asymptomatic vs. symptomatic?)

If symptomatic, then have trophs, so get foul smelling, greasy, floating stool with NO BLOOD (b/c no invasion of mucosa, just attachment), cramping, bloating, gas, NO fever

If asymptomatic, you have cysts and spread Giardia to all your friends

How long does disease last?

Acute: weeks
Chronic: months to years
malnutrition due to malabsorption


observe cysts in formed stool
observe trophs in diarrheal stools


water treatment/filtration when hiking, etc.

Giardia Troph and cyst: what do they look like?

Troph: teardrop shaped, two nuclei (eyes) four pairs of flagella, claw-shaped median bodies, ventral disk, tumbling swimming motions

Cyst: oval and smooth walled
prominent transvers claw-shaped median bodies and longitudinal axostyle

What is the only other of 5 flagelletes that causes disease?

dientomoeba fragilis and most are asymptomatic
if symps: ab pain, flatulence, diarrhea, and weight loss

no cyst stage



What is the claim to fame for Balantidium Coli?

only ciliated pathogen associated with disease in humans


fecal oral from pigs

Sx generally? Can cause?

Asymptomatic; alternating bouts of diarrhea and constipation CHRONICALLY

The acute path is?

INVASIVE so can have blood and pus in stool
simialar to amebic dystentary


a sporozoan

Transmission of Cryptosporidium parvum?

fecal oral

What do you ingest, in particular?


Type of disease caused by Cryptosporidium parvum?



mature oocyst with sporozites gets ingested, then the sporozoans attach to intestinal epithelium and mature, then sexual forms develop and produce fertilized oocyst, mature oocyst in feces


asexual reproduction in small intestine, merozites are relased into the lumen and can infect new intestinal cells perpetuating asexual cycle

What type of reproduction for Cryptosporidium parvum?


What is another source for Cryptosporidium parvum?


Target audience?

very youn and 25-40 yrs


Profuse watery diarrhea with cramps, fatigue; NO BLOOD B/C not invasive

Where can we see Cryptosporidium parvum?

Water, public pools contaminated drinking water


oocyte in stool

What is the Tx?

mainly self limiting


proper sanitization for drinking water

Who is also at risk here?

immunocompromised, AIDS (15-25% of these pts are infected) can be fatal for AIDS patients, so immunity is important here both Ab and cell mediated




sexual sporozoan


fever, diarrhea, weight loss


immature oocyst with sporocyst is injested, mature, sporozoites divide and mature in small intestine of mucosa, sexual forms develop and produce fertilized cyst, becomes oocyst with zygote in feces


Who is most seriously effected?

AIDS PTs: second only to cryptosoridium for causing diarrhea in AIDS pts.

get Watery diarrhea, malabsorption, wt. loss, death




unsporulated oocyte shed from infected folks oocyst sporulation in env --> fecal to oral transmission oocyte get ingested from contaminated env


PROFUSE WATERY DIARRHEA, may have RASPBERRY SEEDS, cramp, fatigue, wt. loss

Disease in AIDS pts more serious


Stool sample with FLOURESCING oocytes under UV!!!!!




intestinal disease or disseminate throughout the body, microsporidiosis

Type of parasite?

obligate intracellular parasite

primitive eukaryotes

worldwide distribution

Infection by?

ingest spores

What we know about disease if from?

increased occurance in AIDS pts


Chronic debilitating diarrhea, anorexia, weight loss, 10-20 stools a day

Extra intestinal Sx?

keratoconjunctivitis is an early indicator of dissemination

symps depend on organ infected



Which has diarrhea that is foul smelling, greasy, and floating?


Which has bloody mucus?


Which is profuse and watery?


Which is profuse and watery W/ RASPBERRY seeds?


Which is seen under UV?


Which can be debilitating to AIDS pts?

Crypto and Isospora

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