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SECTION I - INFECTIOUS AGENT
NAME: Toxocara canis, T. cati
SYNONYM OR CROSS REFERENCE: Toxocariasis, visceral larva migrans, larva migrans visceralis, ocular larva
migrans.
CHARACTERISTICS: Enteric nematode, helminth, larvae are 400 um X 20 um; adults females are 5 to 18 cm long
and adult males 4 to 10 cm long; eggs are about 85 um X 75 um with a thick brown shell.
SECTION II - HEALTH HAZARD
PATHOGENICITY: Two distinct larva migrans infections can occur: visceral larva and ocular larva migrans,
both due to the systemic migration of the larval form of the helminth; visceral larva migrans is characterized
by hepatosplenomegaly, fever, and eosinophilia, symptoms depends on the site and extent of larval migration; ocular
larva migrans symptoms include leukokoria, loss of vision in the affected eye, eye pain and strabismus. Disease
is rarely fatal.
EPIDEMIOLOGY: Worldwide; eggs are ubiquitous in the soil wherever dogs and cats defecate; common in preschool
children with a history of dirt-eating; ocular disease more common in school-age children, increasingly recognized
in humans.
HOST RANGE: Humans, dogs and cats.
INFECTIOUS DOSE: Not known
MODE OF TRANSMISSION: By direct or indirect transmission of eggs from contaminated soil to the mouth; direct
transfer by eating raw, unwashed vegetables and dirt (children).
INCUBATION PERIOD: Varies from weeks to months depending on the intensity of the infection. Eggs infective
after 1-3 weeks incubation.
COMMUNICABILITY: Not directly transmitted from person-to-person.
SECTION III - DISSEMINATION
RESERVOIR: T. canis in dogs; T. cati in cats.
ZOONOSIS: Yes - disease transmitted by contaminated feces of dogs and cats.
VECTORS: None
SECTION IV - VIABILITY
DRUG SUSCEPTIBILITY: Sensitive to diethylcarbamazine, thiabendazole.
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 1% sodium hypochlorite (20% commercial bleach), 2% glutaraldehyde.
PHYSICAL INACTIVATION: Eggs are sensitive to drying.
SURVIVAL OUTSIDE HOST: Eggs can remain viable in soil for many months.
SECTION V - MEDICAL
SURVEILLANCE: Monitor for symptoms; confirm by ELISA testing, microscopic demonstration of eggs in tissue
samples.
FIRST AID/TREATMENT: Administration of appropriate drug therapy; typically diethylcarbamazine for visceral
larva migrans, corticosteroids for ocular larva migrans.
IMMUNIZATION: None available.
PROPHYLAXIS: None available.
SECTION VI - LABORATORY HAZARDS
LABORATORY-ACQUIRED INFECTIONS: None reported to date.
SOURCES/SPECIMENS: Blood and blood products; feces; ocular tissues.
PRIMARY HAZARDS: Ingestion; contamination of mucous membranes; skin penetration of larvae.
SPECIAL HAZARDS: Avoid the generation of aerosols when working with infected laboratory animals; avoid contact
with contaminated feces.
SECTION VII - RECOMMENDED PRECAUTIONS
CONTAINMENT REQUIREMENTS: Biosafety level 2 practices and containment for activities involving the infective
stage of the parasite, infectious body tissues and fluids.
PROTECTIVE CLOTHING: Laboratory coats; gloves when skin contact with infectious materials is unavoidable.
OTHER PRECAUTIONS: Good personal hygiene and frequent hand washing.
SECTION VIII - HANDLING INFORMATION
SPILLS: Allow aerosols to settle; wearing protective clothing, gently cover 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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