Rat Bite Fever can occasionally present as a vasculitis syndrome. The patient may be initially misdiagnosed as having an autoimmune disease.
Pathogen: Streptobacillus moniliformis or Spirillum minus
Clinical features may include:
(1) fever
(2) polyarthritis
(3) skin rash that may be macular or papular
(4) sore throat
(5) headache
Skin biopsy may show a leukocytoclastic vasculitis.
Laboratory testing may show a positive ANCA and/or ANA test.
The initial diagnosis may be rheumatoid arthritis (RA), ANCA vasculitis or SLE.
Clues to the correct diagnosis:
(1) history of rat or pet bite
(2) positive culture or PCR of blood or synovial fluid
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Specialty: Infectious Diseases
