A parasite, over 100 spp in various animals. S. hominis, S. nesbitii, and S. suihominis are the cause of human in- fections..
Eating the organism I suppose but the literature is opaque (PubMed).
Fever (relapsing in half of patients), myalgia, headache, cough , and eosinophila. Muscle biospy makes the diagnsosis (PubMed).