Rickettsiae

• Rickettsiae


  Obligate intracellular parasites
• Rickettsiae


  • Size smaller than bacteria ranging from 0.3 to 0.5 um in width & 0.3 to 2.0 in length
  • Shape is pleomorphic, cocobacillary (fat rods) in shape
  • Employ arthropods (fleas, lice, mites, ticks)
• Rickettsial Diseases


  • Rocky mountain spotted fever
  • Epidemic Typhus
  • Murine Typhus
  • Tsutsugamushi
  • Ricketsial Pox
  • A. Fever
• Fever


  A symptom of rickettsial diseases
• Rocky Mountain Spotted Fever

  • Causative agent: Rickettsia Rickettsii
  • Vector: wood and dog ticks
  • Reservoir: wild rabbit
  • Symptoms: malaise, abrupt fever, muscle and joint pains; rash on wrist and ankles spreading to the body
• Epidemic Typhus


  • Causative agent: R. Prowazekii
  • Vector: Human body lice
  • Reservoir: Human
  • Symptoms: abrupt severe aches, fever, chills, rash on back and chest spreading down
• Murine Typhus


  • Causative agent: R. Typhi
  • Vector: rat, fleas
  • Reservoir: rodents
  • Symptoms: similar to those epidemic typhus but milder
• Tsutsugamushi


  • Causative agent: R. tsutsugamushi
  • Vector: mites
  • Reservoir: wild rats and mice
  • Symptoms: abrupt onset and chills, rash on trunk spreading peripherally
• Rickettsial Pox


  • Causative agents: R. Akari
  • Vector: mouse, mite
  • Reservoir: house mite
  • Symptoms: lesion at site of bite, chills fever, generalized rash
• A. Fever


  • Causative agent: C. Burnetti
  • Vector: Ticks, body lice
  • Reservoir: wild rodents, cattle, sheep, goats
  • Symptoms: fever, malaise, frequently cough and patchy pneumonia; no rash