The top reason people attribute to Lyme becoming more common is a warmer climate. As the climate changes, ticks are out longer (as temperature exceeds freezing) and that their hosts may be changing and/or increasing in number.
According to a research article conducted by Mayo and Carnegie Mellon, the life cycle of a tick that transmits Lyme “usually takes two to three years to complete and goes through three stages, all of which are dependent on environmental factors.” They concluded that increased temperature and humidity increase tick survival rates.
More specifically, the Vector Disease Control International says that “increases in temperature, changes in precipitation patterns, increases in extreme weather, and rising sea levels are capable of influencing the life cycle, distribution, and prevalence of vector-borne diseases by altering habitat availability and reproduction rates.”
Climate change also affects animal reservoirs because the geographic range for animals expands and shifts. Ticks are able to survive because they have an animal reservoir (another animal they can pass Borrelia burgdorferi to). According to University of San Francisco doctor and professor Charles Chiu, “the expansion of the animal reservoir…increase[s] the risk of infections to humans by maintating the tick population in the wild.”
Another reason that warmer climates (for longer periods of time) may contribute to the rise in Lyme disease is that people are outside more often when the nymphs are also out. They are so small and often difficult to detect, which means there is a higher risk for the tick to go unnoticed and unremoved. People aren’t as educated and precautions aren’t in place. The best way to prevent Lyme disease is to avoid getting bitten by a tick, so there would be less Lyme cases if people knew what precautions to take.
Not only are people outside more, but they travel out of state more often, as well, potentially getting infected on the east coast and then traveling home to an area where Lyme is less common. This globalization is a potential reason for why Lyme rates have been increasing in different regions. Lyme has been reported in all 50 states; however, we know it is much more common on the east coast.
Lyme may also be spreading more rapidly because of the increase in deer population, which is one way in which ticks are becoming infected. According to a study by Penn State College of Agricultural Sciences, researchers conducted a study in which they observed that the removal of wolves had a huge impact, finding that “when large carnivores disappear, it can devastate the ecology.” An example in Lancaster Online shows that because there is an upsurge in coyotes, there are more mice—which carry Lyme. Likewise, cougars and wolves are preying on different animals than coyotes and bobcats. Hence, the higher density of deer.
While the media may consider Lyme disease to be a hot topic (with celebrities like Avril Lavigne and Yolanda Hadid at the head of the conversation), it seems as though Lyme isn’t just being talked about for that reason—it seems to really be on the rise. Thousands of cases are going unreported each year, and with more awareness and more research, we hope the predicted 20 percent increase in Lyme cases won’t actually come true.