Highly pleomorphic, filamentous, gram negative rod.
S. moniliformis is the classic organism. There is also S. hongkongensis isolated from 2 human patients, S. felis from the lung of a cat, S. ratti from black rats, and S. notomytis from a spinifex hopping mouse and a human case in Japan from rats (PubMed).
At least 30% can't recall a rat exposure.
Can also get infection after drinking rat contaminated water or milk.
Incubation is 3-10 days
Fever (often relapsing), rash (mostly on the hands and feet) and polyarticular arthritis. The arthritis may exist without the symptoms of classic rat bite fever: "Asymmetrical polyarticular involvement of the peripheral joints is typical for streptobacillary arthritis. In contrary to streptobacillary rat-bite fever, skin rash and bacteremia is uncommon (PubMed)."
The odd endocarditis.
It is part of the normal respiratory flora of rats and up to 100% of wild and pet rats can carry it.
Relevant links to my Medscape blog
Last Update: 07/05/18.