Tick bite ER visits hit highest weekly rates since 2017

Why are emergency rooms seeing a rise in tick-related visits while many people are still transitioning out of winter?

The answer lies in a combination of specific weather patterns and the biological nature of ticks. According to the U.S. Centers for Disease Control and Prevention, emergency department visits for tick bites are currently at their highest weekly rate for this time of year since 2017. While the Northeast is bearing the brunt of this trend, the Midwest is also seeing an increase in activity.

Wisconsin’s record wet spring triggers early emergence

In Wisconsin, the increase in visits reflects a broader regional trend. Data from the state Department of Health Services for the week ending April 19 revealed a rate of 44 tick-bite visits for every 10,000 emergency room visits. Xia Lee, a DHS public health entomologist, noted that this figure is about double the number of ER visits seen during the same period last year.

The catalyst is a record-breaking spring. Despite a winter that felt more normal than in recent years, February was nearly 6 degrees warmer than usual. That warmth was followed by the wettest April on record for the state. These conditions are ideal for ticks, which thrive in warm, humid environments.

“Compounded with the deer ticks already out there, what we’re seeing is just this large spike in the number of (emergency department) visits because there are more ticks out there a lot earlier,”Xia Lee, DHS public health entomologist

Lee reported that warmer weather is prompting wood ticks to emerge approximately two weeks earlier than normal. This early activity creates a dangerous overlap with the deer ticks already present in the environment. In Dane County, the impact is already visible at the local level; urgent care centers reported at least 35 tick-related visits in a single week, compared to 17 visits during the same timeframe last year, according to reporting from WKOW.

The climate link and the Lyme disease trajectory

The connection between shifting weather and tick behavior is more than a seasonal fluke. Andrew Lewandowski, a pediatrician and board member for Healthy Climate Wisconsin, attributes the trend to climate change, which he says is increasing the number of frost-free days. This allows ticks to emerge sooner and increases their biting behavior.

“With some of these warm snaps that we get in the winter time, it’s increasing the timeframe that ticks can be active and can spread disease,”Andrew Lewandowski, pediatrician and board member for Healthy Climate Wisconsin

The stakes for this increase in activity are high. Wisconsin recorded a record 6,469 cases of Lyme disease in 2024. Over the last 20 years, cases in the state have quadrupled, a trend driven by both biological spread and improved recognition and reporting. PJ Liesch, an extension entomologist at UW-Madison, noted that deer ticks—the most common culprit in the region—have expanded their reach from the woods of northwestern Wisconsin to nearly every corner of the state.

For more on this story, see Rare Tick-Borne Meat Allergy Confirmed Deadly in First Fatal Case: New Jersey Man Dies Hours After Eating Beef, Tied to Alpha-Gal Syndrome from Lone Star Bites.

The risk of infection is high among these populations. Liesch stated that an average of 20 percent of juvenile deer ticks and 40 percent of adult deer ticks are positive for Lyme disease. Because of the current weather patterns, Dr. Greg Demuri, a professor of pediatric infectious diseases at the University of Wisconsin School of Medicine and Public Health, believes the region is headed for a big year for Lyme.

A decade of creeping growth in the Northeast

The trend is not isolated to the Midwest. In the Northeast, emergency room visits for tick bites have climbed to their highest levels for this time of year in nearly a decade. This rise persists even in areas that experienced harsh, snowy winters, which often lead the public to believe tick activity will be suppressed.

Julie McCarthy, the assistant public health director for nursing and behavioral health for the town of Needham, Massachusetts, explained that ticks are really hardy and capable of finding shelter in burrows, bushes, and long grass to survive the cold. She described the steady increase in data over the last 10 years as jarring, but it’s not surprising.

According to McCarthy, as reported by NBC Boston, this long-term rise is fueled by three primary factors: growing tick populations, a wider geographic spread, and a heightened public awareness that leads to more testing and better reporting.

The risk extends beyond the wilderness. While long grass remains the primary hazard, McCarthy warned that tick encounters can happen in well-manicured backyards. This reality has shifted the prevention strategies for residents, some of whom are now treating their pets as the primary vector for bringing ticks into the home. Sharon Woo, a dog owner in Jamaica Plain, noted that she has seen more ticks on her dogs this year, leading her to vaccinate her pets against Lyme disease—a precaution she had not taken in previous years.

Identifying risks and preventing infection

The danger of the current surge is compounded by the size of the ticks. From late May to mid-July, ticks can be as small as a poppy seed, making them difficult to detect during a visual check. While not every bite results in illness, ticks can transmit various diseases, including anaplasmosis, ehrlichiosis, the Powassan virus, and Lyme disease.

Public health officials, including those from Public Health Madison & Dane County, emphasize that the first 30 days after a bite are critical.

• Fever and chills
• Rashes
• Headaches and fatigue
• Muscle or joint aches

To mitigate these risks, health experts recommend showering within two hours of being outdoors to wash off unattached ticks. A full body check is essential, focusing on hidden areas such as the scalp, ears, groin, and armpits. For those heading into high-risk areas, the use of insect repellent containing DEET is recommended. McCarthy noted that many people mistakenly associate DEET only with mosquitoes, but it remains a critical component of tick prevention.

As the season progresses toward the typical June peak, the focus remains on early detection and the use of protective clothing to avoid the tall grasses where ticks typically wait for a host.