Long-Forgotten Research Unearths New Mystery about Lyme Disease

The tick hunter was hopeful he had found the cause of the disabling illness, recently named Lyme disease, that was spreading anxiety through leafy communities east of New York City. At a government lab in Montana, Willy Burgdorfer typed a letter to a colleague, reporting that blood from Lyme patients showed “very strong reactions” on a test for an obscure, tick-borne bacterium. He called it the “Swiss Agent.”