Murine typhus is caused by Rickettsia typhi and R. felis, which are transmitted to humans by fleas; it is clinically similar to but milder than epidemic typhus, causing chills, headache, fever, and rash.

Animal reservoirs include wild rats, mice, and other rodents. Rat fleas and probably cat fleas transmit the agent to humans. Distribution is sporadic but worldwide; the incidence is low but higher in rat-infested areas.

After an incubation of 6 to 18 days (mean 10 days), a shaking chill accompanies headache and fever. The fever lasts about 12 days; then temperature gradually returns to normal. The rash and other manifestations are similar to those of epidemic typhus but are much less severe. The early rash is sparse and discrete. Mortality is low but is higher in elderly patients.

Diagnosis

Murine typhus is identified by immunofluorescence assay (IFA), immunohistology of a skin biopsy, PCR, and enzyme-linked immunosorbent assay (ELISA).

Treatment

• Doxycycline

Primary treatment is doxycycline 200 mg po once followed by 100 mg bid until the patient improves, has been afebrile for 24 to 48 h, and has received treatment for at least 7 days. Chloramphenicol 500 mg po or IV qid for 7 days is 2nd-line treatment. (For details of treatment, see Rickettsiae and Related Organisms: Treatment.)

Incidence has been decreased by reducing rat and rat flea populations. No effective vaccine exists.

Last full review/revision November 2012 by William A. Petri, Jr., MD, PhD