Tests for Lyme disease miss many early cases — but a new approach could help

As a kid in rural Connecticut in the early 2000s, Kathleen McWilliams was well acquainted with the danger of ticks. After days spent playing outside in the wooded areas around her house, “our home routine was you brushed your teeth, you went to the bathroom, and you did a tick check,” she said.

So when, at age 15, McWilliams suddenly spiked a 104-degree fever, her mom immediately thought Lyme disease, the tick-borne illness caused by the bacterium Borrelia burgdorferi. She requested a Lyme test. While they waited for results, McWilliams’s symptoms morphed into near-constant dizziness and achy joints, two more markers of the disease.

But, after two weeks had passed, they got surprising news: Her Lyme test came back negative.

Had it been positive, McWilliams’s doctor would