The herd, lacking natural predators, continued to grow. A decade ago, a consistent level of about 60 deer roamed the island. Fifteen deer is considered the optimum, safe level for 600 acres - the size of Monhegan. In 1989, Lyme disease entered the picture. The disease, named for the Connecticut town where it was discovered two decades ago, is spread by deer ticks that attach to humans.
Deer serve as hosts for the tick.
Lyme disease can cause joint pain and fatigue and may lead to arthritis and neurological and heart problems. Eighteen contract disease Since 1989, a total of 18 year-round and summer residents on Monhegan have contracted the disease. The incidence rate of 10 percent is five times higher than the general population, leading some to call Lyme disease on Monhegan an epidemic. Islanders began working with the Maine Medical Center Lyme Disease Research Program, which has led efforts to eradicate the deer tick. Small and isolated, the island is an ideal research area.