Lect 7 Flashcards
Giardia lamblia is found in what animals
beavers, dogs, cats, primates
- zoonosis, cross infectivity between animals and humans
Giardiasis is most common in what patient population
children
Giardiasis is caused by what organism (name both names)
- Giardia lamblia / G. intestinalis
is Giardiasis motile
Flagellate protozoan: very motile
Giardiasis has what two life stages
- Trophozoite
- exists freely in small intestine
- teardrop shape, flagella, 2 nuclei
- feeds on mucus secretions, does not invade tissue
- Cyst
- form passed into environment
- 4 nuclei
- 1 cyst produces 2 trophozoites
what is this organism
Giardiasis
give the life cycle of Giardiasis
- ingestion of cyst (infectious stage)
- Excystation occurs in stomach
- Trophozoites pass into small bowel and divide
- trophozoites in large bowel encyst
- cysts pass into environment
how is Giardiasis passed
drinking water contaminated with feces
when is Giardiasis infection most prevalent
June-October
clinical presentation of Giardiasis that seperates it from other parasites
- watery diarrhea (No blood), abdominal cramps
- vitamin B 12 deficiency
- can be a STI
how is Giardiasis diagnosed
- cysts and/or trophozoites in stool sample
- ELISA dectection of (Giardia specific enzymes 65) GSA 65
protective features against Giardiasis
- human milk - IgA
- phagocytes can kill trophozoites
Amoebiasis is caused by what organism
Emtamoeba histolytica
Describe the two forms of Emtamoeba histolytica
- Trophozoite
- amoeboid with 1 nucleus
- non-flagellated
- pseudopod forming (how it walks)
- invasive and pathogenic
- Cyst
- round in shape
- 4 nuclei
- infectious stage
what is this organism
Emtamoeba histolytica
describe the life cycle of Emtamoeba histolytica
- ingestion of cysts
- excystation in colon
- trophozoites colonize in mucosa of colon
- can encyst and pass in feces OR invade intestinal mucosa
how is E. histolytica contracted
fecal contamination of water and food
Name some high risk populations to getting E. histolytica
- children
- pregnant woman
- long term corticosteroid
- oral-anal sexual practices
clinical presentation
- abd cramps
- bloody stools
- fever
- vomiting
- unintentional weight loss
- Rt upper quadrant pain
E. histolytica
Amoeba hydrolyzes the intestinal lining which results in what condition
- ulcers
- presents as right upper quadrant pain
- death can occur from peritonitis, cardiac failure, exhaustion
List the virulence factors of E. histolytica
- Lectin: adhesion to host cell
- Phospholipases: disrupt host cell membrane
- Amebapore: inserts ion channels into host lipid structure -> lysis of host cell
- Cysteine proteases: degrades mucus, antibody, complement and cellular matrix
how is E. histolytica diagnosed
- trophozoites or cysts in stool sample
- CT and MRI to reveal large cysts (abscesses)
- ELISA to indentify E. histolytica
- PCR
what other condition can E. histolytica create all over the body that is diagnosed with CT/MRI
abscess
Why are E. histolytica infections emerging in backyard pools
cysts are resistant to chlorine
Cryptosproridiosis is caused by at least 15 different species, but name the most important two
- Cryptosporidium hominis
- Cryptosporidium parvum
Reservoir for Cryptosporidium hominis
humans
reservoir for Cryptosporidium parvum
bovine and human
name the two forms of Cryptosporidium
-
Oocysts
- contain 4 sporozoites
- infectious stage
- do not multiply outside of host
-
sporozoites
- motile
- bind receptors on surface of intestinal epithelial cells
how does Cryptosporidium reproduce
sexual and asexual reproduction
describe the life cycle of Cryptosporidium
- ingestion of oocysts
- activates and releases 4 sporozoites
- sporozoites bind to receptors on intestinal epithelial cells
- ingested into parasitophorous vacule (replaces cell membrane with itself)
- sexual/asexual reproduction
- asexual -> thin walled oocyte -> reinfect host
- sexual -> thick walled oocyte -> shed into environement
transmission of Cryptosporidium
- endemic: person to person
- sporatic: contaminated water and food
- animal (cows) to human
why is Cryptosporidium found in recreational water
resistant to chlorine
why are Cryptosporidium infections hard to treat
- Extracytoplasmic, but intracellular
Cryptosporidium mainly affects what patient population
children
clinical presentation
- watery diarrhea
- dehydration, weight loss, fever, abd pain
- lasts for 2 weeks (self limited in immunocompetent person)
Cryptosporidium
how id Cryptosporidium identified
- isolate oocysts in stool sample
- Immunofluroescence
- ELISA
Cyclosporiasis is caused by what organism
Cyclospora Cayetanensis
How is the oocyst of cyclospora cayetanensis different than other organisms
- autofluorescene oocyst
- larger than oocyst of cryptosporidium
cyclospora cayetanensis is associated with ingestion of oocysts in what
- water
- imported foods (fresh fruits and vegetables)
how is the life cycle of cyclospora cayetanensis different from other organisms
- ingestion of oocysts
- oocysts shed in feces MUST SPORULATE in the environment
- requires days
clinical presentation
- low grade fever
- chills
- abd crampls
- N/V
- explosive, non-bloody-watery diarrrhea
- rapid weight loss
cyclospora cayetanensis
how is cyclospora cayetanensis identified
- Large oocyst in stool sample
- acid fast positive, autofluorescent oocyte
- PCR
What organism has a large central vacuole and multiple nuclei distributed around rim of cytoplasm
Blastocystis hominis
how does someone get Blastocystis hominis
ingestion of cysts from contaminated food or water (animal feces)
Which organism has a large intestine microbe that has a MACROnucleus and cilia
Balantidium coli
reservoir for Balantidium coli
Zoonotic (pigs)
what can happen from Balantidium coli infection
gut perforation
