Lyme disease was first identified in 1975, in Lyme, Conn., but scientists still have more questions than answers about how the bacteria responsible for the condition that wreaks such havoc for some people, leaving them with debilitating symptoms for years, while causing relatively mild disease for others. Tests for Lyme have high false negative rates, especially early in the infection, so even detecting the disease is challenging.

In a paper published in PLOS Pathogens, an international group of researchers report on the most comprehensive analysis of the Borrelia burgdorferi genome to date, which provides clues about what’s causing more severe forms of the disease, and lays the foundation for developing better diagnostic tests and treatments. The data come from samples painstakingly taken from 299 Lyme patients in the northeastern and midwestern U.S., and central Europe, mostly extracted from skin biopsies of the bullseye-shaped rashes that are a hallmark early sign of infection. The scientists first isolated the bacteria from the biopsied skin samples, then correlated genetic signatures of the bacteria with the patients’ health outcomes. That allowe…