Occupational risk of Lyme disease in endemic areas of New York State.

Although Lyme disease (LD) is the most common tick-borne disease in the United States, little is known about the frequency of and risk factors for infection with Borrelia burgdorferi in occupational groups. In 1986, we recruited primarily outdoor workers from six employee groups in southeastern New York where LD is endemic. Of 414 participants who completed questionnaires and had blood samples tested for antibodies against B. burgdorferi by ELISA and Western immunoblot, 27 (6.5%) were seropositive, but only 14 of the 27 reported previous symptoms of LD. Persons who spent more than 30 hours per week outdoors during leisure were 2.5 times more likely to be seropositive than those who did not (p = .02). Those with a history of outdoor employment were twice as likely to be seropositive as those without such a history, although this finding was not statistically significant (p = .70). However, the seroprevalence rate for the employees was 5.9 times higher than the rate for a comparison group of anonymous blood donors from the same region of New York (p less than .001). These results suggest that there was a relatively high rate of seropositivity for the employee groups and that infection was frequently asymptomatic and associated with outdoor exposure.