Fort Chaffee revisited: the epidemiology of XXXX at a natural focus.

@entity3403 @entity281 @entity16736 @entity221 @entity7545
A retrospective cohort study was conducted among troops training at Fort Chaffee, Arkansas, from May through June 1997, to identify @entity281 caused by tick-borne pathogens. Serum samples were tested by IFAs for antibodies to selected @entity16736 and Ehrlichia species and by an investigational EIA for spotted @entity221 group @entity16736 lipopolysaccharide antigens. Of 1,067 guardsmen tested, 162 (15.2%) had antibodies to one or more pathogens. Of 93 guardsmen with paired serum samples, 33 seroconverted to @entity16736 or spotted @entity221 group rickettsiae (SFGR) and five to Ehrlichia species. Most (84.8%) of the personnel who seroconverted to SFGR were detected only by EIA, and seropositivity was significantly associated with an illness compatible with a @entity7545 . In addition, 34 (27%) of 126 subjects with detectable antibody titers reported a compatible illness. The primary risk factor for confirmed or probable disease was finding > 10 ticks on the body. @entity3403 use and rolling up of long sleeves were protective against seropositivity. The risk of transmission of tick-borne pathogens at Fort Chaffee remains high, and use of the broadly reactive EIA suggests that previous investigations may have underestimated the risk for @entity281 by SFGR. Measures to prevent tick bite and associated disease may require reevaluation.
