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Rickettsial Diseases

Rickettsial diseases are caused by the Rickettsiagenus of bacteria, and spread by ticks and mites. In Canada, the only rickettsial disease observed to occur is Rocky Mountain Spotted Fever.

Information for Health Professionals

Rickettsial diseases are a group of diseases with similar symptoms caused by bacteria of the genus Rickettsia. These bacteria are spread by the bite of an infected tick or mite. Of these, only Rocky Mountain Spotted Fever (RMSF) has been observed to occur in Canada.

Names of other rickettsioses include:

  • Boutonneuse fever
  • African tick bite fever
  • Queensland tick typhus
  • North Asian tick fever
  • Tick-borne lymphadenopathy (tibola)
  • Flinders Island spotted fever
  • Australian spotted fever
  • Far-eastern tick-borne rickettsiosis
  • Oriental spotted fever
  • Maculatum infection
  • Rickettsialpox
 

Symptoms may include: 

  • fever
  • rash
  • a scab at the bite wound
  • inflammation of the blood vessels and/or lymph system

The incubation period ranges from two to 15 days.

The rickettsioses are spread by hard (ixodid) ticks or mites, and generally occur worldwide. The causative agent of RMSF is Rickettsia rickettsii. In northwestern US and western Canada, it is spread by the Rocky Mountain wood tick - Dermacentor andersoni. In eastern North America, the American dog tick, D. variabilis, is responsible. 


The tick may inject the rickettsia directly, after being attached for several hours, or its feces or crushed body may infect the bite wound or open sores.

 More serious forms of illness can include:

  •  enlargement of the liver and spleen (hepatosplenomegaly)
  • bleeding
  • kidney (renal) failure
  • heart failure
  • neurological problems

Overall, the fatality rate varies and is generally low, especially with treatment. It increases with age, and can reach 30 per cent or more if left untreated (RMSF).

 

 

Tests vary, and include serology:

  • identifying antibodies in the blood, and
  • microbiology - identifying the organism through culturing or observing it through a microscope.
 

Treatment of rickettsial diseases is with antibiotics.

 

 

Prevention focuses on the avoidance of ticks and mites, and the prompt removal of attached ticks. 

  • When hiking in grassy areas, wear long pants, and if possible, tuck the cuffs of your pants into your socks.
  • Wear a repellent containing DEET.
  • Check yourself and others, including pets, after hiking and remove any ticks.
  • Remove any attached ticks by grasping the tick with needle-nose tweezers, as close to the skin surface as possible, and pulling straight up, with a steady pressure. Do not squeeze the tick's body, or apply anything to it, since this may cause it to disgorge its stomach contents into the bite wound.
  • Clean the wound well with soap and water. You may also apply an antibiotic ointment.
  • Wash your hands.

Refer to HealthLink BC File #01, Tick Bites and Disease.


 

References: Control of Communicable Diseases Manual, Heymann, 2008 Public Health Agency of Canada

Last Updated: May 7, 2012


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