Vermont may have nudged out Maine to become the state with the highest incidence of Lyme disease. Preliminary data show 1,091 cases reported to the Vermont Department of Health in 2017, up from 763 in 2016, when Vermont ranked second in the country for cases per capita. Actual numbers are likely much higher; the Centers for Disease Control and Prevention estimates that only one in 10 cases gets reported. Children ages 5 to 14 are most likely to contract Lyme because they spend lots of time outdoors and are lower to the ground, said Pat Bannerman, vice president of the education and support group VTLyme.org. Lyme disease is caused by an infection with a bacterium called Borrelia burgdorferi. In the Northeast, it is transmitted to humans by the bite of a black-legged tick, formerly known as the deer tick, said Bradley Tompkins, the health department's tickborne disease program chief. Most transmission to people comes from young ticks called nymphs, which look like poppy seeds and are most active in the spring and early summer, Tompkins said. Adult black-legged ticks, which look like large sesame seeds, also transmit Lyme and are more active in the fall. The health department recommends removing ticks at home — an instructional video is available on the department website — then seeking medical care if symptoms, including a rash, headache, fever, chills, fatigue, and muscle and joint pain, start, usually within three to 30 days. Antibiotics are used to treat the disease.