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SECTION I - INFECTIOUS AGENT
NAME: Giardia lamblia
SYNONYM OR CROSS REFERENCE: Giardia intestinalis, Giardiasis, Giardia enteritis, Lambliasis
CHARACTERISTICS: Flagellated protozoa, trophozoite (9-21 um long, 5-15 um wide and 2-4 um thick) contains
2 nuclei and 4 flagella with tumbling motility; cyst form develops in the colon.
SECTION II - HEALTH HAZARD
PATHOGENICITY: Varies from asymptomatic in most individuals to a sudden onset of diarrhea with foul-smelling,
greasy-looking stool that lacks mucous and blood; associated with abdominal cramps, bloating, fatigue and weight
loss; restricted to upper small intestine with no invasion.
EPIDEMIOLOGY: Worldwide; prevalent in areas with poor sanitation; outbreaks more common in children than
in adults; waterbome outbreaks are common where unfiltered waters are routinely contaminated by human and animal
feces.
HOST RANGE: Humans; wild and domestic animals.
INFECTIOUS DOSE: Less than 10 cysts when given orally.
MODE OF TRANSMISSION: Fecal-oral route is most important (hand to mouth transfer of cysts); ingestion of
fecally-contaminated water and food are also mechanisms for transmission.
INCUBATION PERIOD: From 5 - 25 days, usually 7 - 10 days.
COMMUNICABILITY: Cysts are shed during the entire period of infection.
SECTION III - DISSEMINATION
RESERVOIR: Humans, wild and domestic animals.
ZOONOSIS: Beaver considered zoonotic reservoir for water-borne infection in headwaters of many cold water streams.
VECTORS: None
SECTION IV - VIABILITY
DRUG SUSCEPTIBILITY: Sensitive to quinacrine hydrochloride, metronidazole and furazolidone.
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 1% sodium hypochlorite (20% commercial bleach); chlorine
in drinking water not sufficient, especially if water is cold)- 2% glutaraldehyde.
PHYSICAL INACTIVATION: Boiling
SURVIVAL OUTSIDE HOST: Cysts remains infectious for prolonged periods in the environment.
SECTION V - MEDICAL
SURVEILLANCE: Monitor for symptoms, confirm by microscopic demonstration of trophozoite and cysts in
feces.
FIRST AID/TREATMENT: Administer appropriate drug therapy, usually Metronidazole.
IMMUNIZATION: None available.
PROPHYLAXIS: None available.
SECTION VI - LABORATORY HAZARDS
LABORATORY-ACQUIRED INFECTIONS: Two cases were reported up to 1987.
SOURCES/SPECIMENS: Feces, duodenal secretions.
PRIMARY HAZARDS: Ingestion.
SPECIAL HAZARDS: None.
SECTION VII - RECOMMENDED PRECAUTIONS
CONTAINMENT REQUIREMENTS: Biosafety level 2 practices and containment facilities are recommended for
activities with infective stages of mammalian Giardia spp. and infectious body fluids and tissues.
PROTECTIVE CLOTHING: Laboratory coat; gloves when skin contact with infectious materials Is unavoidable.
OTHER PRECAUTIONS: None
SECTION VIII - HANDLING INFORMATION
SPILLS: Allow aerosols to settle, wearing protective clothing gently cover the spill with absorbent paper
towel and apply 1% sodium hypochlorite (20% commercial bleach) starting at the perimeter and working towards the
center; allow sufficient contact time (30 min.) before clean up.
DISPOSAL: Decontaminate all wastes before disposal; steam sterilization, chemical disinfection, incineration.
STORAGE: In sealed containers that are appropriately labeled.
Date prepared: October 11, 1997 Prepared by.- Canadian Office of Biosafety Information edited by the Colorado State
University Office of Biosafety- June 16, 1998.
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