GIARDIASIS

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GIARDIASIS

• Causative agent Giardia lamblia (G.
  intestinalis, G. duodenalis)
• Other names lambliasis, beaver fever, lamblia
  intestinalis
• Most common cause of non-bacterial diarrhea in
  North America

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GIARDIASIS

• Features of organism
• a flagellate protozoan parasite
• life cycle includes two forms
• trophozoite active reproducing form with four
  pairs of flagella, two nuclei, attachment disc
• cyst resting stage
• common isolate from digestive tract of humans

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GIARDIASIS

• G. lamblia

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GIARDIASIS

• Features of organism
• reproduce by binary fission
• anaerobic, although aerotolerant
• lack mitochondria, endoplasmic reticulum, golgi,
  lysosomes
• glucose is main food source which is obtained by
  diffusion or pinocytosis

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GIARDIASIS

• Epidemiology
• occurrence worldwide
• prevalence
• ranges from 1 to 30 with estimated incidence in
  US of 2
• higher in areas of poor sanitation and in daycare
  settings
• Canadian study found cysts in 73 of raw sewage
  water samples, 21 raw water, 18 treated water

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GIARDIASIS

• Epidemiology
• year round occurrence in some areas, but more
  likely from June-October in US
• higher frequency of infection in children
• higher frequency of infecion in lt 5 year and
  25-39 year age groups
• outbreaks associated with drinking water that has
  been treated but not filtered

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GIARDIASIS

• Epidemiology
• reservoir man is primary reservoir although
  beaver and other wild and domestic animals may
  serve as reservoir in some regions
• transmission
• direct through oral ingestion of cysts
• hand to mouth (daycare centers)
• contaminated water sometimes food

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GIARDIASIS

• Epidemiology
• key factors in endemic areas
• cysts are highly resistant in environment
• cool moist conditions favor survival
• asymptomatic carriers
• chronic patients
• large number of cysts shed (some patients shed up
  to 900x106 per day)

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GIARDIASIS

• Life cycle

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GIARDIASIS

• Clinical features
• Incubation period 3-25 days or longer
• Infectious dose as little as 1-2 cysts has been
  reported median infective dose (ID50) 25-100
  cysts

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GIARDIASIS

• Clinical features
• Symptoms
• abdominal cramping
• dehydration
• chronic diarrhea
• steatorrhea - fatty, greasy stool
• fatigue
• weight loss

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GIARDIASIS

• Clinical features
• infection may last for months, difficult to treat
  in immunocompromised patients
• cysts shed throughout infection
• generally a non-fatal disease
• may develop intolerance to lactose or other
  disaccharide (40)

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GIARDIASIS

• Clinical features
• chronic infections may lead to malabsorption
• treatment with metronidazole (Flagyl) is
  effective, but may be prolonged
• disease in animals similar to humans and likely
  caused by same organism

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GIARDIASIS

• Diagnosis
• direct examination of cysts or trophozoites in
  stool
• detection of salivary IgA may be more sensitive
  than fecal examination
• ELISA for detection of secretory products

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GIARDIASIS

• G. lamblia trophozoites in diarrhea

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GIARDIASIS

• Prevention and control
• filtration of water supply
• protection of water supply against contamination
• proper disposal of diapers and fecal material in
  daycare centers
• for emergency, boiling best method