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Epidemic Typhus -- Georgia

On January 3, 1984, a 12-year-old male resident of middle Georgia became ill with a fever of 40 C (104 F) and a mild sore throat. No other symptoms or signs, including rash, were noted. Treatment with erythromycin for 4 days provided no clinical improvement, and the patient was hospitalized for further evaluation. Physical examination remained unchanged. No antibiotics were administered during the 8-day hospitalization, and the patient was discharged with the diagnosis of fever of undetermined origin. During the next 2 weeks, he gradually recovered.

Acute- and convalescent-phase serum specimens obtained from the patient were submitted to the Georgia Department of Human Resources, where testing indicated infection with either spotted fever group or typhus group rickettsiae. Additional testing at CDC revealed a fourfold increase in antibody titer against Rickettsia prowazekii, the causative agent of epidemic typhus. In February, state and CDC investigators visited the patient's residence and found a colony of eastern flying squirrels (Glaucomys volans) in the attic near the patient's bedroom. Four flying squirrels were trapped and returned to the CDC laboratories. Three of the four captured squirrels had antibodies against R. prowazekii.

Blood specimens obtained from the patient's parents showed no antibodies against R. prowazekii. Specimens were also obtained from 30 residents of 13 neighboring homes, including two residents of a house known to have been infested with flying squirrels. None of these persons had antibodies against R. prowazekii; no additional flying squirrels were captured in their homes. Reported by ER Watson, MD, P Monroe, PhD, Medical Center of Central Georgia, Macon, H Coleman, Bleckley County Health Dept, JD Smith, RK Sikes, DVM, State Epidemiologist, Georgia Dept of Human Resources; Div of Viral Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The characteristics of sporadically occurring R. prowazekii infection have been previously described (1). To date, 33 cases have been confirmed since 1976 (2-4); all but one have occurred in the eastern United States. Seventy percent of the patients have been 20 years of age or older, and 55% have been male. Like classic louse-borne epidemic typhus, these illnesses have been characterized by fever (100% of patients), headache (82%), skin rash (61%), myalgia (42%), and confusion (41%). The skin rash has been characterized as maculopapular, usually involving the trunk and spreading to the extremities. Seventy-four percent of patients have received therapy with tetracycline or chloramphenicol; recovery has been much more rapid among these patients than among those not receiving appropriate antibiotics. However, no patient with sporadic R. prowazekii infection, regardless of antibiotic therapy, has died. Transmission of R. prowazekii infection from flying squirrels to humans is unproven but highly suggested by the high prevalence of R. prowazekii antibodies and the isolation of the agent from flying squirrels (5,6) and the high proportion of patients (57%) that have either handled the squirrels or their nests or reported squirrels in their homes. Seventy percent of the typhus cases have occurred in the colder months of the year--December, January, February--when flying squirrels tend to congregate and nest in attics of homes to which they can find access. Possible mechanisms of transmission of the infection from flying squirrels to humans include vector (fleas, lice, or other ectoparasites) and airborne transmission of dried, aerosolized excretions (of ectoparasites or of flying squirrels). The limited community study conducted following this case suggests that unrecognized infection in the vicinity of cases is uncommon, even among residents of homes in which flying squirrels have been present.

The evolutionary histories of R. prowazekii infection in flying squirrels and in humans remain unclear; R. prowazekii probably evolved from R. typhi, the causative agent of endemic (murine) typhus, or from a common ancestor (7), but it is not known whether R. prowazekii appeared first in flying squirrels or in humans. Furthermore, it is not known whether flying squirrel-associated typhus infection can be transmitted from human to human by the classic epidemic typhus vector, since these sporadically occurring infections in the United States have not occurred in persons infested with body lice.

CDC is interested in studying cases of flying squirrel-associated epidemic typhus, and particularly, in obtaining an isolate of the causative organism from a patient before antibiotics have been administered. In the coming winter months, therefore, physicians should be alerted to the possibility of this infection and should report any suspicious illness promptly to their local and state health departments and to CDC. A blood specimen should be obtained from the patient before treatment.


  1. CDC. Epidemic typhus associated with flying squirrels--United States. MMWR 1982;31:555-61.

  2. McDade JE, Shepard CC, Redus MA, Newhouse VF, Smith JD. Evidence of Rickettsia prowazekii infection in the United States. Am J Trop Med Hyg 1980;29:277-84.

  3. Duma RJ, Sonenshine DE, Bozeman FM, et al. Epidemic typhus in the United States associated with flying squirrels. JAMA 1981;245:2318-23.

  4. CDC. Unpublished data.

  5. Bozeman FM, Masiello SA, Williams MS, Elisberg BL. Epidemic typhus rickettsiae isolated from flying squirrels. Nature 1975;255:545-7.

  6. Sonenshine DE, Bozeman FM, Williams MS, et al. Epizootiology of epidemic typhus (Rickettsia prowazekii) in flying squirrels. Am J Trop Med Hyg 1978;27:339-49.

  7. Marchette NJ. The typhus complex: Rickettsia typhi and R. prowazekii. Adaptation to insects. In: Ecological relationships and evolution of the rickettsiae. Volume I. Boca Raton, Florida: CRC Press, 1982.

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