5 July 2019
Lyme Disease in Winter
Posted by Shane Hanlon
This is part of a series of posts from our own Shane Hanlon’s disease ecology class that he’s currently teaching at the University of Pittsburgh Pymatuning Laboratory of Ecology. Students were asked to write popular science posts about (mostly) wildlife diseases. Check out all the posts here.
By Alec Kistler
Similar to other wildlife diseases, there are myths about Lyme disease. While many myths exists, one of the most interesting myths about Lyme disease pertains to transmission. People believe that ticks cannot survive in the winter; so, Lyme disease cannot be transmitted during winter.
In the United States, Lyme disease is one of the most common diseases carried by ticks. Lyme disease is caused by the bacteria Borrelia burgdorferi. When an infected blacklegged tick, also known as a deer tick, bites a host, it can transmit the bacteria to the host. It takes approximately 36 – 48 hours for a nymph (juvenile) tick to transmit the bacteria to its host. Adult ticks are also able to pass on the bacteria; however, they are usually spotted and removed before transmission. While Lyme disease is worldwide, it is highly concentrated in northeastern and northern American states. After spending time outside, it is vital to check for ticks. In the summer, it is extremely important to check; but it is also important to check during the winter months.
Unlike summer, winter is deceiving. It is cold during the winter months. Because of the cold, it is challenging for organisms to survive. Due to this knowledge, people have the misconception that ticks cannot survive in winter. This is not true. Depending on the species and life cycle stage of the tick, they are able to survive in the cold. Some tick species can be active above 45 degrees Fahrenheit, while others tick species can be active above 32 degrees Fahrenheit. Below their specific threshold temperature, ticks must go dormant or find a host.
If a tick is unable to find a host, it must go dormant. When a tick goes dormant, they must find a place to hide under leaves, branches, plants, etc. for protection. Anywhere that will provide some shelter against the winter weather. Even snow does not kill ticks. It insulates them. Once the snow thaws, the ticks become active again. Some ticks, such as soft-shell ticks, must burrow underground in order to survive.
If a tick is lucky enough to find a host, they will latch on for the entire winter. During those months, the host provides shelter and nourishment. When the tick is not feeding on the host, it will attach to the organism’s hair. When winter is over, the tick will leave its current host and find a new one.
Climate change is impacting tick activity during winter. Winters are becoming warmer. The temperature is constantly fluctuating; some days the temperature is below 10 degrees Fahrenheit and some days the temperature is above 60 degrees Fahrenheit. The warmer weather allows the ticks to be more active during winter and this can result in an increased number of Lyme disease incidents.
Do not become a victim to the misconception about ticks and Lyme disease. So, while it is more likely to get Lyme disease in the summer, it is not impossible to get Lyme disease in the winter. While it is important to be vigilant during the warmer months, some ticks are still active and the disease can still be transmitted.
Want to read more about Lyme disease? Here is the link to the CDC’s Lyme disease Page.
Want to learn more about ticks during winter? Here is the link.