During the spring of 1989, 86 members of a military unit from the state of Maryland, USA, participated in two-week-long training manoeuvres in the states of Arkansas (location FC) and Virginia (location FAPH). Acute febrile illnesses due to infections with two tick-borne pathogens, Rickettsia rickettsii and Ehrlichia sp., were confirmed serologically in 2 initial cases who were admitted to the hospital. A seroepidemiological investigation among unit members found an additional 17 of 109 individuals (16%) with elevated post-exposure indirect immunofluorescent antibody (IFA) titres to R. rickettsii (16 cases) and/or E. canis (2 cases). The seropositivity rate of personnel who trained at FC was 38% (15 of 40), compared to only 13% (4 of 31) and 8% (3 of 38) of personnel who trained at FAPH or who did not train in the field, respectively (P < 0.001). Seropositivity was associated with symptoms suggestive of a tick-borne illness. Only 4 (22%) and 6 (33%) of the 18 personnel seropositive for R. rickettsii reported an erythematous or petechial type of rash or a febrile illness, respectively, within 4 weeks of exposure; 5 of 18 (28%) personnel infected with R. rickettsii reported no symptoms and only 8 of 18 (44%) received medical treatment. Mild infections with R. rickettsii, or a closely related spotted fever group agent, may have accounted for the high infection rate experienced by this group.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.