Ticks can really get under your skin—literally. And in many parts of the country they spread illness, including Lyme disease and Rocky Mountain spotted fever. Add to that list a new scourge: Heartland virus, which doesn't respond to treatment. This infection was described for the first time last year after two Missouri men were hospitalized with fever and headaches. No one was sure how the men contracted the disease. Now a study in theAmerican Journal of Tropical Medicine and Hygiene confirms that ticks were the transmitters. [Harry M. Savage et al., First Detection of Heartland Virus (Bunyaviridae: Phlebovirus) from Field Collected Arthropods] Researchers tromped out to the two men's properties, and 10 more sites in the region, to set up tick traps. These included containers of dry ice, which emit carbon dioxide to attract ticks, and flannel bedding, which traps them. They also picked some ticks off of area dogs and horses. All told, they collected more than 56,000 tick specimens. And they found the virus residing in lone star ticks—the most common in the region. About one in 500 of the arachnids carried the virus. Enough to make me check for ticks. And then check again. —Katherine Harmon