Entamoeba histolytica

Entamoeba histolytica

MATERIAL SAFETY DATA SHEET - INFECTIOUS SUBSTANCES

SECTION I - INFECTIOUS AGENT

NAME: Entamoeba histolytica

SYNONYM OR CROSS REFERENCE: Amebiasis, Amebic dysentery, Ameboma

CHARACTERISTICS: Obligate parasite of human alimentary tract; possess both cyst (10-15 µm in diameter) and trophozoite forms; trophozoite (12-50 µm in diameter) are microaerophilic with a granular, vacuolated endoplasm and clear ectoplasm with pseudopods

SECTION II - HEALTH HAZARD

PATHOGENICITY: Approximately 90% of most infections are asymptomatic, only evidence may be seroconversion; debilitated, pregnant or immunocompromised individuals may develop an abrupt onset of fever, severe abdominal cramps, profuse bloody diarrhea and tenesmus; complications include massive hemorrhage, peritonitis, amebomas and liver abscesses

EPIDEMIOLOGY: Worldwide distribution;10% of world's population is infected with E. histolytica; stool survey in the US indicated that 5% of the population harbors E. histolytica; higher incidence in areas of the tropics with poor sanitation; common in mental institutions and among sexually promiscuous male homosexuals

HOST RANGE: Humans, primates

INFECTIOUS DOSE: Not known; however, theoretically, the ingestion of one viable cyst can cause infection

MODE OF TRANSMISSION: Ingestion of fecally contaminated water and food (raw vegetables), oral-anal sexual contact; by fecally contaminated hands of foodhandlers

INCUBATION PERIOD: Variable, from a few days to several months; usually 2-4 weeks

COMMUNICABILITY: During the period of cyst passing and may continue up to several years

SECTION III - DISSEMINATION

RESERVOIR: Humans (chronically ill or an asymptomatic cyst passer - can excrete 15 million [15 x 106] cysts per day)

ZOONOSIS: None

VECTORS: None

SECTION IV - VIABILITY

DRUG SUSCEPTIBILITY: Susceptible to metronidazole, tinidazone, ornidazole, deloxanide furoate, iodoquinol, dehydroemetine, chloroquine, tetracycline

SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 1% sodium hypochlorite, 2% glutaraldehyde, 2% tincture of iodine, cysts are relatively resistant to levels of chlorination used in standard water purification

PHYSICAL INACTIVATION: Cysts are sensitive to heating above 50° C

SURVIVAL OUTSIDE HOST: Cysts are sensitive to drying, trophozoites are rapidly killed by drying, water, urine and barium

SECTION V - MEDICAL

SURVEILLANCE: Monitor for symptoms; confirm by microscopic demonstration of trophozoites or cysts in faecal specimens, serological assays

FIRST AID/TREATMENT: Administration of appropriate drug therapy; extraintestinal disease is most difficult, needle aspiration of liver abcess may be indicated with antibiotic use

IMMUNIZATION: None available

PROPHYLAXIS: None available

SECTION VI - LABORATORY HAZARDS

LABORATORY-ACQUIRED INFECTIONS: 23 cases were reported up to 1987

SOURCES/SPECIMENS: Fecal specimens, abscess aspirate, tissue sections

PRIMARY HAZARDS: Ingestion; direct contact of mucous membranes with infectious materials

SPECIAL HAZARDS: None

SECTION VII - RECOMMENDED PRECAUTIONS

CONTAINMENT REQUIREMENTS: Biosafety level 2 practices and containment facilities for activities involving the infectious stages of the parasite and the manipulation of known or potentially infectious tissues or body fluids

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

OTHER PRECAUTIONS: Frequent handwashing and proper hygiene practices are important

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 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 labelled

SECTION IX - MISCELLANEOUS INFORMATION

Date prepared: January, 2001

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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