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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