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17 Cards in this Set
- Front
- Back
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What is Giardia?
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It is a pathogenic flagellated protozoon first observed by Leeuwenhoek. It is the most common flagellate isolated in clinical specimens.
Four pairs of flagella emerge from the ventral surface, which is concave and acts like a suction cup for attachment to a substrate. |
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What are symptoms of Giardia?
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Diarrhea of long duration, abdominal pain and flatulence. Fever is not usually present.
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What is the pathogenesis of Giardia?
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Ingested cysts enter the duodenum, germinate and travel to the jejunem to feed. Some trophozoites remain on the surface, while others invade the deeper crypts to varying degrees. Epithelial cells are damaged with resulatant edema and WBC. Maladsorption esp of fat, is common as is weight loss.
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Where is Giardia found normally?
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It has been isolated from the intestines of beavers, cattle, coyotes, cats and human carriers. Cysts play a greater role in transmission. Infections can occur with ingestion of 10-100 cysts esp. in water or food.
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How is Giardia diagnosed?
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It is shed in feces intermittently. Elisa and PCR tests are functional.
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How is Giardia treated?
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There is a vaccine for animals, but not for humans.
All suspected sources, even clean water sources that are not certified should be avoided. It is killed by boiling, iodine and ozone. Quinacrine and metronidazole are used as therapeutic aids. |
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What is Entamoeba histolytica?
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The life cycle of this parasite alternates between a large trophozoite that is motile by means of pseudopods and a smaller non motile cyst.
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Is the trophozoite similar to other eukaryotes?
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No. It lacks most of the organelles and it has a large single nucleus that has a prominent nucleolus called a karyosome.
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What does the mature cyst look like?
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It is encased in a thin yet tough wall and contains 4 nuclei as well as a distinctive cigar shaped bodies called "chromotoidal bodies" which are dense clusters of ribosomes.
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What are the signs of Amoebiasis/
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It exists in an intestinal and extraintestinal form.
the targets of intestinal amoebiasis is the cecum, appendix colon, and rectum. The amoeba secretes enzymes that dissolve tissues and it penetraytes deeper layers of the mucosa leaving erosive ulcers. |
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What are the symptoms that follow?
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This phase is marked(intestinal) by dysentery, abdominal pain, fever diarrhea and weight loss. Hemorrhage, perforation, appendicitis and tumor growths called amoebomas are seen.
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What is Amoebic extraintestinal infection?
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here, the amoebas invade the viscera of the peritoneal cavity. A common site is the liver. Abscesses, containing necrotic tissue and trophozoites develop and cause amoebic hepatitis. occasionally, pulmonary amoebiasis is seen as well. fatality rate may approach 10%.
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What is the pathogenesis of Amoebiaia?
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1. it begins when viable cysts are swallowed and arrive in the small intestine, where the alkaline pH stimulate excystment.
2. Each cyst releases 4 trophozoites, which are swept into the cecum and large intestine. 3. Trophozoites attach here by fine pseudopods, they multiply and move about. |
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The severity of Amoebiasis infection can vary with the strain of the parasite, inoculum size diet and host resistance. TRUE/FALSE
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TRUE. The secretion of lytic enzymes by the amoeba seems to induce apoptosis of host cells.
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Who are the primary hosts of E. histolytica?
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Humans are. Infection is acquired by ingesting food or drink contaminated with cysts released by the asymptomatic carrier.
It is believed to be carried by 1/10 of the worlds population. |
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How is E. histolytica cultured and diagnosed?
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Microscopic exam of stool for cysts or trophozoites, Elisa tests for antigens.
It is important to differentiate E. histolytica from the similar E. coli and E. dispar, which occur as normal flora. |
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How is E. histolytica treated?
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Drugs such as iodoquinol, which acts in the feces, and metronidazole or chloroquine.
dehydroemetine is used to control symptoms. reinfection is possible. |
