Results were obtained for 1973 of those bitten. There were 50 cases of Lyme disease. Overall risk of a single bite was calculated at 2.6%; influencing factors were: 1) Engorgement: low engorgement risk 1.4%, very engorged risk 5 percent. 2) Patient reported duration of attachment: less than 12 hours risk of disease 2 %, greater than 4 days ....