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Lecture 6
Parasitology/Intestinal Protozoa - Giardia and Others
Question | Answer |
---|---|
What are two other names for Giardia lamblia? | Giardia duodenalis or G. intestinalis |
What is the transmissible form of Giardia lamblia? | Cyst |
Which form of Giardia lamblia causes disease? | Trophozoites |
Compare the size of the cyst and trophozoites forms of Giardia lamblia. | Cysts: 10um Trophozoites: 20um |
Name some mammals that can cause zoonotic transmission of Giardia lamblia to humans. | Livestock, cats, dogs, beavers |
Which patients are probably at risk for developing worse Giardia infections? | agammaglobulinemic patients |
What are the epidemiologic exposures that should make one consider Giardia lamblia as part of the differential diagnosis in the US? | Day care, waterborne outbreaks, hikers, foreign travel |
True/False: Giardia lamblia can cause symptomatic and asymptomatic infection. | True |
What is are the symptoms of active Giardia lamblia infection? | Foul-smelling diarrhea, abdominal cramping, bloating lasting weeks and often resulting in weight loss. |
How does Giardia lamblia cause symptoms? | Trophozoites multiply and attach to small bowel epithelium by a sucking disk which leads to malabsorption. |
True/False: During asymptomatic infection with Giardia lamblia people can pass trophozoites. | False: They are “cyst passers”. |
How is diagnosis of Giardia lamblia made? | 1.Antigen detection: ELISA/IF 2. Stool microscopy to visualize cysts on a stained smear or motile trohphozoites on a saline wet mount. 3. Duodenal sampling (rare) |
What are the drugs of choice for treating Giardia lamblia? | Tinidazole or metronidazole |
How is infection with Giardia lamblia prevented? | Fecal-oral hygiene, boiling, filtering, iodine works on water |
How are people infected by Cryptosporidium spp.? | Ingestion of oocysts. |
What is the leading cause of diarrhea in AIDS? | Cryptosporidium spp. |
What is the normal course of infection with Cryptosporidium spp. in immunocompetent pts? | self-limited diarrhea, abd pain for 2 wks. Fever is rare |
What are the complications with AIDS and Cryptosporidium spp. infection? | Severe, chronic debilitating diarrhea and dissemination (cholangitis, other sites) |
How do you diagnose infection with Cryptosporidium spp.? | Antigen detection (ELISA/IF), Stool microscopy (staining of oocysts with acid-fast stain), Endoscopy with biopsy. |
What is the treatment for Cryptosporidium spp.? | Cryptosporidium is generally highly resistant to chemotherapy. Can use nitazoxanide and for AIDS HAART should be started. |
What are the strategies for preventing infection with Cryptosporidium spp.? | 1.Fecal-oral hygiene 2. Screen pets of AIDS pts. 3. Boiling and <1um filters |
Does chlorine or iodine kill Cryptosporidium spp.? | no |
What organism causes disseminated diarrhea and keratitis in AIDS pts? | Microsporidia spp. |
What is the treatment for Microsporidia spp? | Albendazole or fumagillin |
What are the two organisms which cause diarrhea in AIDS pts and are treated with TMP/SMX? | Isospora belli and Cyclospora cayetanesis. |
True/False: Cyclospora cayetanesis is foodborne and can be found in raspberries and mesclun. | True |
What is the only life cycle form of Trichomonas vaginalis? | Trophozoite |
How is Trichomonas vaginalis transmitted? | Human to human sexual transmission |
What are the possible increased risks with Trichomonas vaginitis? | Pre-term delivery and may increase HIV transmissibility |
What are the clinical features of Trichomonas vaginitis? | Vaginal discharge and irritation (similar to candida vaginitis or bacterial vaginosis) asymptomatic in men. |
How is the diagnosis of Trichomonas vaginitis made? | On exam: copious yellow bubbly discharge, elevated pH (>5), on wet mount of d/c: WBCs and motile trophozoites |
What is the treatment for Trichomonas vaginalis infection? | Metronidazole single dose to pt and partner |
How is Trichomonas vaginalis transmission prevented? | Condoms |