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SECTION I - INFECTIOUS AGENT
NAME: Yersinia pestis
SYNONYM OR CROSS REFERENCE: Plague, Peste, Bubonic plague
CHARACTERISTICS: Gram negative rod, ovoid, bipolar staining (safety pin appearance), facultative intracellular
parasite.
SECTION II - HEALTH HAZARD
PATHOGENICITY: Zoonotic disease; bubonic plague with lymphadenitis in nodes receiving drainage from site
of flea bite, occurring in lymph nodes and inguinal areas, fever, 50% case fatality if untreated; may progress
to systemic plague with dissemination by blood to meninges; secondary pneumonic plague with pneumonia, mediastinitis,
and pleural effusion; untreated pneumonic and septicemic cases are fatal.
EPIDEMIOLOGY: Wild rodent plague in North America, South America, Africa, Near and Middle East, Central
and Southeast Asia, Indonesia; plague foci in USSR; urban plague controlled in most areas; human plague occurred
recently in Africa; endemic in Burma and Vietnam; sporadic cases in North and South America following exposure
to wild rodents or their fleas (no human-to-human transmission in USA since 1924).
HOST RANGE: Humans, various animals.
INFECTIOUS DOSE: Unknown.
MODE OF TRANSMISSION: Result of human intrusion into zoonotic (sylvatic) cycle or by entry of rodents or
infected fleas into human's habitat and bite of infected fleas; domestic pets can carry plague-infected fleas;
contact of commensal rodents and their fleas with sylvatic rodents may result in epizootic and epidemic plague;
handling of infected tissues; airborne droplets from humans or pets with plague pneumonia; careless manipulation
of laboratory cultures; person-to-person transmission by human fleas.
INCUBATION PERIOD: From 2-6 days; may be a few days longer in vaccinated individuals; for primary plague
pneumonia, 1-6 days, usually short.
COMMUNICABILITY: Fleas may remain infective for months; bubonic plague not usually transmitted directly
from person to person; pneumonic plague may be highly communicable under appropriate climatic conditions (overcrowding
facilitates transmission).
SECTION III - DISSEMINATION
RESERVOIR: Wild rodents (rats) are the natural reservoir; lagomorphs (rabbits, hares) and carnivores
(especially cats via aerosol) may be a source of infection to humans.
ZOONOSIS: Yes - bites of fleas from an infected animal; contact (especially aerosol) or being bitten by
an infected animal.
VECTORS: Wild rodent fleas, especially the oriental rat flea (Xenopsylla cheopis); occasionally by human
fleas (Pulex irritans).
SECTION IV - VIABILITY
DRUG SUSCEPTIBILITY: Sensitive to streptomycin, tetracycline, chloramphenicol.
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to many disinfectants - 1% sodium hypochlorite (20% commercial
bleach), 70% ethanol, 2% glutaraldehyde, iodines, phenolics, formaldehyde.
PHYSICAL INACTIVATION: Sensitive to moist heat (121o C for at least 15 min.) and dry heat (160o
- 170o C for at least 1 hour).
SURVIVAL OUTSIDE HOST: Blood - 100 days; human bodies - up to 270 days.
SECTION V - MEDICAL
SURVEILLANCE: Monitor for symptoms; presumptive diagnosis by visualizing bipolar staining, ovoid, gram-negative
organisms in sputum or material aspirated from bubo; FA and ELISA test; PHA using Fraction-1 antigen.
FIRST AID/TREATMENT: Antibiotic therapy in early stages (8-24 hours after onset of pneumonic plague) typically
tetracycline or streptomycin; secondary infection or suppurative bubo may require incision and drainage.
IMMUNIZATION: Although field trials have not been conducted to determine the efficacy of licensed vaccines,
experience has been favorable; immunization is recommended for personnel working regularly with cultures of Y pestis
or infected rodents.
PROPHYLAXIS: Chemoprophylaxis using tetracyclines or sulfonamides; for close contacts of pneumonic cases.
SECTION VI - LABORATORY HAZARDS
LABORATORY-ACQUIRED INFECTIONS: 10 reported laboratory acquired infections with 4 deaths.
SOURCES/SPECIMENS: Bubo fluid, blood, sputum, CSF, feces, urine.
PRIMARY HAZARDS: Direct contact with cultures and infectious materials from humans or rodents; infectious
aerosols or droplets generated during manipulation of cultures and infected tissues and in the necropsy of rodents-,
accidental auto-inoculation; ingestion.
SPECIAL HAZARDS: Bites by infected fleas collected from rodents.
SECTION VII - RECOMMENDED PRECAUTIONS
CONTAINMENT REQUIREMENTS: Biosafety level 2 practices, containment equipment and facilities for all activities
involving the handling of potentially infectious clinical materials and cultures. Additional primary containment
and personnel precautions as described for BL3 are recommended for activities with high potential for droplet or
aerosol production, for work with antibiotic-resistant strains, and for activities involving production, large
quantities, or high concentrations of infectious materials.
PROTECTIVE CLOTHING: Gloves should be worn when handling field-collected or infected laboratory rodents
and when there is the likelihood of direct skin contact with infectious materials; gown with tight cuffs and ties
in back should be worn when manipulating cultures and specimens.
OTHER PRECAUTIONS: Special care should be taken to avoid the generation of aerosols during the necropsy
of animals- necropsy should be conducted in a biological safety cabinet.
SECTION VIII - HANDLING INFORMATION
SPILLS: Allow aerosols to settle; wearing protective clothing, gently cover spill with paper towels and
apply 1% sodium hypochlorite (20% commercial bleach), starting at perimeter and working towards the center, allow
sufficient contact time (30 min) before clean up.
DISPOSAL: Decontaminate before disposal; steam sterilization, incineration (animal carcasses).
STORAGE: In scaled containers that are appropriately labeled.
Date prepared: October 11, 19 97 Prepared by: Canadian Office of Biosafety Information edited by the Colorado State
University Office of Biosafety; June 16, 1998.
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