Ascaris lumbricoides

Ascaris lumbricoides

MATERIAL SAFETY DATA SHEET - INFECTIOUS SUBSTANCES

SECTION I - INFECTIOUS AGENT

NAME: Ascaris lumbricoides

SYNONYM OR CROSS REFERENCE: Ascariasis, roundworm infection, ascaridiasis

CHARACTERISTICS: Largest and most common intestinal nematode in humans; fertile eggs are oval to subspherical, 45-75 µm by 35-50 µm and are covered by a thick shell with a light brown mammillated, albuminous outer coat; unfertile eggs are thin-walled, ellipsoidal; found in the small intestine, particularly the jejunum

SECTION II - HEALTH HAZARD

PATHOGENICITY: Symptoms correlate with worm load: light loads are asymptomatic; heavier loads cause abdominal symptoms, diarrhea and malnutrition. A bolus of worms may obstruct the intestine; migrating larvae may cause pneumonitis and eosinophilia

EPIDEMIOLOGY: Worldwide; greatest prevalence in the moist tropical countries where incidence exceeds 50%; incidence highest in children 3-8 years old

HOST RANGE: Humans

INFECTIOUS DOSE: Not known

MODE OF TRANSMISSION: Ingestion of infective eggs from soil contaminated with human faeces, uncooked produce contaminated with soil containing infective eggs

INCUBATION PERIOD: Variable; life cycle requires 4-8 weeks to be completed; faeces contain fertile eggs about 60 days after ingestion of embryonated eggs

COMMUNICABILITY: For as long as mature fertilized female worms are alive in the intestine transmission is possible; usual life span of adult worm is 12 months, maximum is 24 months

SECTION III - DISSEMINATION

RESERVOIR: Humans; ascarid eggs in soil

ZOONOSIS: None

VECTORS: None

SECTION IV - VIABILITY

DRUG SUSCEPTIBILITY: Susceptible to mebendazole, albendazole, pyrantel pamoate

SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 1% sodium hypochlorite, 2% glutaraldehyde; ascaris eggs are resistant to chemical disinfectants and temporary immersion in strong chemicals

PHYSICAL INACTIVATION: Sensitive to heat

SURVIVAL OUTSIDE HOST: Eggs may remain viable in favourable soil for years

SECTION V - MEDICAL

SURVEILLANCE: Monitor for symptoms; confirm by microscopic examination for eggs in faeces or for passage of adult worms

FIRST AID/TREATMENT: Administer appropriate drug therapy

IMMUNIZATION: None available

PROPHYLAXIS: None available

SECTION VI - LABORATORY HAZARDS

LABORATORY-ACQUIRED INFECTIONS: Eight cases reported

SOURCES/SPECIMENS: Stool specimens

PRIMARY HAZARDS: Ingestion; direct contact of eggs with mucous membranes; skin penetration of larvae

SPECIAL HAZARDS: Avoid generation of aerosols when working with infective stages of Ascaris since frequent exposure to aerosolized antigens can lead to hypersensitivity

SECTION VII - RECOMMENDED PRECAUTIONS

CONTAINMENT REQUIREMENTS: Biosafety level 2 practices and containment facilities for activities involving infective stages of the parasite, infectious body tissues and fluids

PROTECTIVE CLOTHING: Laboratory coat; gloves when skin contact with infectious material is unavoidable

OTHER PRECAUTIONS: Work in a biosafety cabinet when chance of aerosolizing antigens

SECTION VIII - HANDLING INFORMATION

SPILLS: Allow aerosols to settle; wearing protective clothing, gently cover spill with absorbent paper towel and apply 1% sodium hypochlorite starting at the perimeter and working towards the centre; 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 labelled

SECTION IX - MISCELLANEOUS INFORMATION

Date prepared: November 1999

Prepared by: Office of Laboratory Security, PHAC

Although the information, opinions and recommendations contained in this Material Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.

Copyright © Health Canada, 2001

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