Rising Lyme Disease Cases Due to Expanding Tick Habitats and Climate Change: How to Protect Yourself

In 2021, emergency room visits due to tick bites have reached their highest level since 2017, according to data from the US Centers for Disease Control and Prevention (CDC). Simultaneously, reported cases of Lyme disease continue to increase annually.

Experts attribute these increases to warmer temperatures resulting from climate change and the expanding presence of ticks in more areas across the United States and Canada, even in regions where people are less aware of the risks and prevention methods.

Dr. Thomas Daniels, director of the Louis Calder Center at Fordham University’s biological field station, recalls that when he first began research in the mid-1980s, there were few reported cases of Lyme disease in Canada. Today, the disease is well established in the country.

Deer ticks, which are most active when temperatures exceed 45 degrees Fahrenheit and thrive in humid environments with at least 85% humidity, according to the US Environmental Protection Agency (EPA), are primarily responsible for transmitting Lyme disease. During their nymph stage, these ticks are about the size of a poppy seed, making them easy to miss. As they feed on blood, they can transmit pathogens, including Borrelia burgdorferi, which causes Lyme disease.

Brian Fallon, director of the Lyme and Tick-Borne Diseases Research Center at Columbia University, stated that infection with this bacterium can cause a variety of multisystem symptoms. Once in the bloodstream, the bacteria may travel to various parts of the body, including the heart, central nervous system, brain, or peripheral nerves.

Lyme disease symptoms often manifest as a pinkish, reddish rash that expands from a small size to five centimeters or larger over time. Some individuals may experience multiple rashes on different parts of their bodies as the disease progresses without treatment. Symptoms can last for months or even years if left untreated.

Dr. Erin Mordecai, an associate professor of biology at Stanford University, noted during a news briefing that the rising temperatures due to human impacts on climate change make conditions more suitable for disease transmission in the United States and North America.

While climate change plays a role in the expansion of tick habitats, changes in landscapes caused by human activities also significantly influence where ticks are found. Dr. Jean Tsao, a professor at Michigan State University who studies disease ecology, explained that most changes in tick ranges in the continental US are likely due to modifications in wildlife communities resulting from land use change and white-tailed deer management.

Prevention methods against Lyme disease include prompt tick removal and wearing more clothing during summer months to keep ticks on the outside of the body. Ticks can also be repelled using permethrin, an insecticide. When hiking, it’s advisable to stay on trails and perform a “tick check” for yourself and others if you’re in an area with ticks. Showering at the end of the day may help wash off unattached ticks.

If a tick has been attached for an extended period, it gradually expands, becoming as large as a raisin due to continuous blood-sucking. Experts recommend using tweezers to remove the tick from beneath its body and advise against attempting to burn or poison the tick.