If unrecognized and untreated, the organism is disseminated by hematogenous spread to multiple body sites. Several secondary erythema migrans lesions may develop and are usually smaller than the primary lesion. Flu-like symptoms occur, and meningitis can rarely develop. Carditis presenting as a heart block can occur but is also rare. A frequent sign is paralysis of the 7th cranial nerve, commonly known as Bell's palsy. One in four cases of Bell's palsy occurs in warm weather due to Borrelia burgdorferi. The facial paralysis may last 2–8 weeks.
