The incubation period is usually 2 to 10 days. The bite wound frequently has healed by the time symptoms appear. A morbilliform or petechial rash, which is most marked on the extremities, particularly the hands and feet, develops in most patients shortly after the onset of fever. Arthralgias and polyarthritis in both large and small joints are characteristic features. The fever may recur.
Abscesses sometimes complicate disseminated infection.
If untreated, the febrile illness and articular manifestations persist for several weeks. Prolongation of symptoms beyond several weeks should raise suspicion of a complicating endocarditis. The diagnosis is made by isolation of the organism from blood or, less commonly, from synovial fluid. The fever, rash, and articular manifestations of S. moniliformis infection may resemble those of meningococcemia, but meningitis is usually not a feature of streptobacillary infection. Rocky Mountain spotted fever, leptospirosis, and echovirus infection have similar presentations.