Scientists are warning of a particularly bad tick season this year as warmer weather arrives. Emergency room visits for tick bites reached record highs for April since tracking began in 2017, according to CDC data, with elevated rates across most of the country except the south-central United States. These figures likely represent only a fraction of actual tickborne illnesses, according to Nicole Baumgarth, professor of immunology and infectious disease at Johns Hopkins Bloomberg School of Public Health and director of its Lyme and Tickborne Diseases Research and Education Institute.

Ticks transmit serious diseases including Lyme disease, Rocky Mountain spotted fever, and alpha-gal syndrome (which can cause a red meat allergy). A Lyme disease vaccine is in development and shows promise, but it would require multiple initial doses plus annual boosters, leading experts to doubt it will become a widespread solution beyond the most avid outdoors enthusiasts. Tick populations are rising due to climate change—favoring warm, humid conditions and mild winters—and expanding northward, along with abundant hosts like deer and thriving white-footed mouse populations that help spread Lyme.

Public health officials note that despite ongoing efforts, the upward trend in tickborne illnesses has not been reversed. The CDC recommends several prevention steps: avoid grassy, bushy, or wooded areas; treat clothing with 0.5% permethrin; use insect repellents; check clothing and perform full-body tick checks after being outdoors (including under arms, around ears, hairline, belly button, and back of knees); dry clothes on high heat for 10 minutes; check pets; and shower within two hours of coming indoors.