Co-infections: Rickettsia Diseases

Some Diseases Caused by the Rickettsia Bacteria

Ehrlichiosis  (HME, human monocytic ehrlichiosis)

Anaplasmosis (HGA, human granulocytic anaplasmosis, formerly called HGE)

Rocky Mountain Spotted Fever (RMSF)

Spotted Fever Group Rickettsias (SFGR)
May cause milder illness than Rocky Mountain spotted fever



Ehrlichiosis, Anaplasmosis, and Rocky Mountain Spotted Fever share Similar Symptoms

  • Fever
  • Chills
  • Severe headache
  • Muscle aches or pain
  • Confusion
  • Meningitis
  • Abdominal pain
  • Nausea
  • Vomiting (sometimes)
  • Diarrhea (sometimes)
  • Rash

 Rickettsia Disease Rash

  • Flat red and/or bumpy rash.
  • Rash doesn’t appear for several days.
  • Many people with Rocky Mountain spotted fever don’t get a rash.
  • The rash is rare in anaplasmosis and ehrlichiosis.
  • The RMSF rash typically begins at the wrists and ankles and moves up the limbs.
  • May also occur on the palms of the hands and soles of the feet.
  • Spotted fever group rickettsias may cause a milder illness than these other diseases.

Rocky Mountain Spotted Fever Picture

Rocky Mountain Spotted Fever Feet



Diagnosis Issues

  • Rickettsial diseases can be confused with the flu or viral meningitis.
  • They may not get diagnosed until the rash appears.
  • These diseases cause low platelet count, low white blood cell count, and elevated liver enzymes. A CBC panel and liver enzyme test should be ordered.
  • Antibody tests can be ordered, but treatment must not wait for the antibody test results.
  • Antibody tests for anaplasma are likely to be negative during the first week or two of infection.
  • People can get Lyme disease along with these diseases.

Treatment of Rickettsial Diseases

  •  Treatment is most successful if begun promptly (before the 5th day of illness).
  • Don’t wait for test results.
  • Tests are usually negative early in the illness.
  • Begin treatment as soon as a rickettsial disease is suspected.
  • These diseases can be fatal if treatment is delayed.

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