Recent lesson from a clinical and seroepidemiological survey: low positive predictive value of Borrelia burgdorferi antibody testing in a high risk population.

PURPOSE: The evaluation of the correspondence between positive Borrelia burgdorferi antibody response and the clinical symptoms attributed to Lyme disease is especially important in labour rights-related issues among forestry workers.
MATERIAL AND METHODS: Between 1992 and 1995, 1670 forestry workers were surveyed and tested serologically for Lyme borreliosis in Hungary. The collected data was analysed retrospectively.
RESULTS: In the case histories of the forestry employees erythema migrans, polyneuropathy and large joint arthritis were mentioned in 128 (7.7%), 192 (11.5%), and 93 (5.6%) workers, respectively. We found positive Borrelia burgdorferi s.l. antibody reaction in 622 workers out of whom 280 (45%) were free of any signs or symptoms referring to B. burgdorferi s.l. infection in their case histories. The frequency of seropositivity increased with age, number of registered tick bites, and erythema migrans in case history, as well as arthralgia. The frequency of polyneuropathy was somewhat more closely corresponding with age than seropositivity. Women gave account of a smaller number of tick bites, and were less likely seropositive while fewer of them were symptom-free. Since the 45% of seropositive forestry workers were symptom-free and they could not recall any symptoms suggestive for present or past Lyme borreliosis, the positive predictive value of Borrelia antibody testing in this high-risk group is surprisingly low, less than 5%.
CONCLUSION: Positive Borrelia antibody test result may be especially misleading in a high-risk population.