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.
References
CDC. Epidemic typhus associated with flying squirrels--United
States. MMWR 1982;31:555-61.
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.
Duma RJ, Sonenshine DE, Bozeman FM, et al. Epidemic typhus in
the
United States associated with flying squirrels. JAMA
1981;245:2318-23.
CDC. Unpublished data.
Bozeman FM, Masiello SA, Williams MS, Elisberg BL. Epidemic
typhus rickettsiae isolated from flying squirrels. Nature
1975;255:545-7.
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.
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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