Giardiasis Flashcards
Life cycle: What is responsible for signs and symptoms of Giardia?
Trophs attach to the surface lining cells and cause symptoms
Life cycle: What part of the cyst is most important in transmission
Cysts have an outer wall to protect them
Life cycle: What is Excystation?
Step 1 Release of parasite from cyst in the small intestine
Life cycle: Each cyst releases how many parasites?
Each cyst releases 2 trophs
Life cycle: What is Encystation?
formation of cyst from trophs; with giardia smooth wall cyst can contain 2 trophs
Clinical: Describe the clinical manifestations of Giardia
- Acute diarrhea x 7-10 days, watery, foul-smelling (Concern with dehydration in children)
- Incubation period is 7-10 days
- Abdominal discomfort
Chronic diarrhea =/- malabsorption, weight loss
Asymptomatic “infection can occur”
Occasional lactase deficiency with or after infection (important to avoid dairy, as it will prolong symptoms)
Describe the Epidemiology of Giardia
HIGHLY CONTAGIOUS (infection spreads with only 10 or more cysts) - Fecal oral (person to person) - Day care (person to person) - Sex practice (person to person) - Water - Foodborne (after fecal contamination) Traveller's Diarrhea
Describe the Diagnosis of Giardia
Giardia stool antigen (most cost effective) polyclonal or monoclonal antibody against cyst or trophozoite antigens is used, whether with an immunoflourscent antibody test or ELISA
- useful to dx or r/o giardia
- Ab or ELISA (highly specific/sensitive test)
- Fecal leukocytes (WBC) absent (no inflammation)
- Duodenal aspirate and/or biopsy or “string test:
- Stool for O & P (ova and parasite exam) can be negative even with infection. Organisms can be shed intermittently
- No serologic test available
Describe the Treatment of Giardia
TINIDAZOLE (DOC - drug of choice)
- single dosing
- avoid dairy 1 month
- also: metronidazole (was DOC, still used)
- empiric therapy for presumed giardiasis in very selective patients= diarrhea for longer than 3 weeks or lab w/u negative but patient “at risk” by hx
Explain prevention of Giardia
- proper handling/treatment of water (chlorination)
- hand washing
- avoid oral-anal
- campers: boil/treat H2O w/ chlorine/iodine
- small volume personal water filter
How can we prevent this disease?
- Proper handling & treatment of water
- Good personal hygiene
- Campers & travelers to filter/boil water
What are Trophozoites?
- The active form that grows and replicates by binary fission
- Protozoan enteric flagellate. Single cell protozoa