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SECTION I - INFECTIOUS AGENT
NAME: Rickettsia rickettsii
SYNONYM OR CROSS REFERENCE: Rocky Mountain Spotted Fever (RMSF), New World spotted fever, Tickborne typhus
fever, Sao Paulo fever.
CHARACTERISTICS: Pleomorphic gram-negative organism, intracellular.
SECTION II - HEALTH HAZARD
PATHOGENICITY: Sudden onset with moderate to high fever persisting 2-3 weeks, malaise, deep muscle pain,
severe headache, chills and conjunctival injection; maculopapular rash appears on extremities on the 3rd day and
spreads rapidly; hemorrhages are common; 15-20% case fatality rate in absence of therapy but with treatment death
is uncommon; clinical syndrome may be confused with atypical measles, meningococcemia and enteroviral infection.
EPIDEMIOLOGY: Occurs throughout United States during spring, summer and fall; many cases along south-Atlantic
seaboard and the South Central Rocky Mountain region; incidence is higher in children; some infections in Canada,
Central and South America. HOST RANGE: Humans, dogs, rodents, various other small animals.
INFECTIOUS DOSE: < 10 organisms.
MODE OF TRANSMISSION: Ordinarily by bite of an infected tick; several hours of attachment are required before
the rickettsiae become reactivated to infect man; by contamination of skin with crushed tissues or feces of tick.
INCUBATION PERIOD: From 3 to 14 days.
COMMUNICABILITY: Not directly transmitted from person to person.
SECTION III - DISSEMINATION
RESERVOIR: Maintained in nature in ticks by transovarian and transtadial passage; transmitted to humans,
dogs, various rodents and animals.
ZOONOSIS: Yes - bite from ticks from infected animals; contamination of broken skin or mucous membranes
with feces or internal contents of crushed tick from infected animal.
VECTORS: Ticks - Eastern and Southern USA - dog tick, Dermancentor variabilis.
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Northwest USA - wood tick, D. andersoni |
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Southwest USA - Lone Star tick, Amyblyomma americanum. |
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Latin America -A. cajennense. |
SECTION IV - VIABILITY
DRUG SUSCEPTIBILITY: Sensitive to tetracyclines and
chloramphenicol.
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 1% sodium
hypochlorite (20% commercial bleach), 70% ethanol, glutaraldehyde, formaldehyde.
PHYSICAL INACTIVATION: Sensitive to moist heat (121o C for at least 15 min.) and dry heat (160-170o
C for at least 1 hour).
SURVIVAL OUTSIDE HOST: Organism is stable in tick tissues or blood under ambient environmental conditions,
surviving up to one year; sensitive to drying-feces of infected ticks quickly lose their infectivity on drying.
SECTION V - MEDICAL
SURVEILLANCE: Monitor for febrile illness and report symptoms immediately, confirmation by serological
test. Sometimes the organism may be detected in blood.
FIRST AID/TREATMENT: Appropriate antibiotic therapy in the early stages of infection should be initiated
on clinical and epidemiologic considerations without waiting for laboratory confirmation of the diagnosis. Typically
treated with tetracycline or chloramphenicol.
IMMUNIZATION: None licensed; but may be available as killed experimental product from U.S. CDC.
PROPHYLAXIS: Early antibiotic treatment leads to delayed onset of illness or relapse (tetracyclines and
chloramphenicol do not kill Rickettsia).
SECTION VI - LABORATORY HAZARDS
LABORATORY-ACQUIRED INFECTIONS: Documented hazard to laboratory personnel; 63 cases reported up to 1976,
11 of which were fatal; one report of 9 cases occurring over a 6-year period in one lab (exposure to infectious
aerosols).
SOURCES/SPECIMENS: Naturally and experimentally infected mammals, their ectoparasites, and their infected
tissues.
PRIMARY HAZARDS: Accidental parenteral inoculation and exposure to infectious aerosols (successful aerosol
transmission documented in non-human primates).
SPECIAL HAZARDS: None
SECTION VII - RECOMMENDED PRECAUTIONS
CONTAINMENT REQUIREMENTS: Biosafety level 2 practices, containment and facilities for all nonpropagative
laboratory procedures including serological and fluorescent antibody tests, and staining of impression smears;
biosafety level 3 for all other manipulations of known or potentially infectious materials, including necropsy
of infected animals and trituration of their tissues, and inoculation, incubation and harvesting of embryonated
eggs or tissue culture.
PROTECTIVE CLOTHING: Gloves and gown (tight wrists and ties in back) when working with agent.
OTHER PRECAUTIONS: Animal biosafety level 2 practices and facilities are recommended for holding of experimentally
infected rodents, however, all necropsy and manipulation of tissue should be conducted at Biosafety level 3.
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 all wastes before disposal: incineration, steam sterilization.
STORAGE: In sealed containers that are appropriately labeled.
Date prepared: October 11, 1997 Prepared by: Canadian Off-ice of Biosafety Information edited by the Colorado State
University Office of Biosafety; June 16, 1998.
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