THE GEOGRAPHICAL-DISTRIBUTION OF TICK BITES AND ERYTHEMA MIGRANS IN GENERAL-PRACTICE IN THE NETHERLANDS

Background. Lyme disease is caused by Borrelia burgdorferi which is tr ansmitted in Europe by the tick Ixodes ricinus. Erythema migrans is a skin lesion which is pathognomonic of Lyme disease. A retrospective st udy was carried out to determine the geographical distribution of the occurrence of tick bites and erythema migrans in the Netherlands and t o identify ecological risk factors, Methods. In April 1995, all genera l practitioners (GPs) in the Netherlands were asked to complete a post al questionnaire on the number of tick bites and erythema migrans case -patients seen in 1994 and the size of the practice, Reminders were se nt to non-responders, information on ecological risk factors by local government area was obtained from a geographical information system. R esults. The response rate was 79.9%. In 1994, GPs reported seeing appr oximately 33 000 patients with tick bites and 6500 with erythema migra ns. The incidence rate of erythema migrans was estimated at 4.3 per 10 000 population. Ecological risk factors for both tick bites and eryth ema migrans were the proportion of the area covered by woods, sandy so il, dry uncultivated land, the number of tourist-nights per inhabitant and sheep population density, The cattle population density was a ris k factor for erythema migrans. Conclusions. Using simple methods, a cr ude estimate of the incidence rate of erythema migrans was obtained ra pidly, and high risk areas were identified, Lyme disease appears to be an important problem in the Netherlands.