You Wouldn’t Know it if a Bug Bit You!
September 30, 1999
You Wouldn’t Know it if a Bug Bit You!
Abstract & Commentary
Synopsis: Antibodies to one or more tick-borne organisms were found at baseline in 88 subjects (13%) residing or working in an area endemic for tick-borne diseases.
Source: Hilton E, et al. Am J Med 1999;106:404-409.
The seroepidemiology of five tick-borne diseases (including Borrelia burgdorferi, Ehrlichia chaffeensis, Ehrlichia equi, Babesia microti, and organisms of the spotted fever group of Rickettsia) was assessed in 835 subjects recruited for participation in a Lyme vaccine study. All of the participants resided or worked in a high-risk area of New York, including Suffolk (n = 828) and Westchester (n = 7) counties, and all of them were routinely active in the outdoors. Sera were obtained at baseline and at one year, and in the event of symptoms suggestive of infection. Follow-up serologies at one year were available for 671 participants.
The seroprevalence of infection at the beginning of the study was similar for all of the organisms (~ 4-5%) with the exception of Babesiosis, which was unusual (1%). Antibodies to B. burgdorferi were the most prevalent, being identified in 34 subjects (5%) at baseline. Seven patients (1%), five of whom were symptomatic, had evidence of seroconversion during the study.
Surprisingly, seroevidence of infection was found in 4% of subjects to either Rocky Mountain Spotted Fever or Ehrlichia, including E. chaffeensis in 23 and E. equi in one. Over the course of the one-year study, five (1%) additional patients seroconverted to E. chaffeensis, including two with symptoms suggestive of ehrlichial infection. Six patients (1%) seroconverted to Rocky Mountain Spotted Fever during the study—none of them had any knowledge of infection due to Rickettsia.
Infection due to B. microti was infrequent; only six (1%) patients had evidence of infection at baseline, and one patient had seroconverted during the study.
Comment by Carol A. Kemper, MD
In summary, antibodies to one or more tick-borne organisms were found at baseline in 88 subjects (13%) residing or working in an area endemic for tick-borne diseases, and 19 subjects (2.8%) seroconverted to one of the organisms during the one-year study. Most of the infections were asymptomatic and detected solely by serological means. Not surprisingly, most of the patients had no recollection of a tick bite, which is fairly common for these infections. Serological evidence of dual infection was unusual (0.8%), and no evidence of co-infection was found during the course of this one-year study. (Dr. Kemper is Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center.)
Which of the following tickborne antibodies was the most prevalent in the study by Hilton et al?
a. B. burgdorferi
b. E. chaffeensis
c. B. microti
d. None of the above
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content