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TICK-BORNE RELAPSING FEVER - USA (02): BACKGROUND
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A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>
Date: Sat 6 Jun 2009
Source: GIDEON (Global Infectious Disease & Epidemiology Network) [edited]
<http://www.gideononline.com/blog/2009/06/05/relapsing-fever-in-the-united-states/>
The following background data regarding relapsing fever in the USA
are abstracted from Gideon at the URL above. Primary references
available on request.
Historical
----------
- Tick-borne relapsing fever was first described in the USA in 1915 (Colorado).
- The 1st case of louse-borne infection in the USA during the 20th
century was reported in 1976, imported from Ethiopia.
Time and place
--------------
- Peak incidence is reported during the summer, with 47 percent of
cases from July to August.
- The disease is most common in Arizona, California, Colorado, and Oregon.
- Sporadic cases are reported from Idaho, Kansas, Montana, Nebraska,
New Mexico, Oklahoma, Texas, Utah, Washington, and Wyoming.
- Most cases occur in the Cascade, Rocky Mountain, San Bernardino,
and Sierra Nevada ranges.
- 40 percent of cases occur in tourists to endemic areas (1977 to 2000).
- Washington and Oregon reported 30 cases during 1965 to 1978.
- Washington reported 24 cases during 1991 to 1994.
- California reported 173 cases during 1964 to 1989; Oregon 73;
Washington 27; Arizona 74; Texas 25; Idaho 13; New Mexico 15; Oklahoma 2.
- California reported 3 to 18 cases yearly during 1985 to 2002.
- Texas reported 13 cases during 1990 to the first half of 1994.
- 5 cases were reported in the Lake Tahoe region of California in
2005, 3 during the summer of 2006.
Incidence
---------
- Tick-borne relapsing fever is reportable in Arizona, California,
Colorado, Idaho, New Mexico, Nevada, Texas, Utah, and Washington.
- 450 cases (300 confirmed and 150 probable) were reported by 11
western states during 1977 to Jan 2000. Only 1 fatal case was
reported during this period, a neonate born to an infected mother.
- 285 cases were reported by California, Colorado, Idaho, Texas, and
Washington during 1985 to 1996.
- There is evidence for the existence of _Borrelia turicatae_ in Florida.
- An American tourist acquired relapsing fever in Israel (1988 publication).
Infecting species
-----------------
- _B. hermsii_ (vector _Ornithodoros hermsii_) and _B. coriaceae_ in
the western region
- _B. turicatae_ (vector _O. turicatae_) in the southwest
- _B. parkeri (vector _O. parkeri_) in the west
- _B. mazzotti_ (vector _O. talaje_) in the south.
Notes regarding transmission
----------------------------
- _Ornithodoros_ is nocturnal and feeds within 20 to 90 minutes,
thus, patients rarely recall the tick bite.
- _B. hermsii_ is maintained in small sylvatic rodents, notably
chipmunks (_Tamias_ spp.) and pine squirrels (_Tamiasciurus_ spp.)
above 1000 meters (3280 ft) elevation.
- Antibodies to _B. hermsii_ are present in 5.4 percent of big brown
bats (_Eptesicus fuscus_). (Georgia, 2007 publication)
-_B. turicatae_ has been detected in dogs in Texas. (2007 publication)
Notable outbreaks
-----------------
All of the following outbreaks were associated with tick
(_Ornithodoros_ spp.) infestations of rodent nests in cabins.
- 1968 -- an outbreak was reported in Spokane County, Washington.
- 1973 -- outbreaks (62 clinical cases, 16 confirmed) were reported
in Grand Canyon National Park, Arizona.
- 1989 -- an outbreak (6 cases) was reported in San Bernardino
County, California.
- 1990 to 1991 -- outbreaks (24 cases, 14 confirmed) were reported in
Grand Canyon National Park, Arizona. No outbreaks were reported in
this area during 1992 to 1999.
- 1995 -- an outbreak (23 family members) was reported among campers
in Colorado.
- 2002 -- an outbreak (5 cases) of _B. hermsii_ infection was
associated with a cabin in western Montana. Infected ticks were
identified at the time.
- 2002 -- an outbreak was associated with a family gathering in New Mexico.
--
Communicated by:
Dr Steve Berger
Geographic Medicine
Tel Aviv Medical Center
Israel
<mberger@post.tau.ac.il>
[ProMED-mail acknowledges Dr Berger's continuing contributions. - Mod.LL]
[see also:
Tick-borne relapsing fever - USA: (CA) 20090605.2083
2006
----
Tick-borne relapsing fever - USA (CA) 20060821.2348
2004
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Tick-borne relapsing fever - USA (MT) 20040727.2052
2003
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Tick-borne relapsing fever - USA (MT): 2002 20030829.2179
2000
----
Borreliosis, relapsing fever - Israel: background 20000423.0607
Borreliosis, relapsing fever, soldiers - Israel 20000423.0602
1999
----
Borreliosis, relapsing fever - Sudan (south) (04) 19990511.0767
Borreliosis, relapsing fever - Sudan (south) 19990429.0713
1998
----
Tickborne disease - USA (California) (02) 19980425.0771]
...................................ll/mj/dk
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