For Lyme disease to thrive in the United States, tick populations also need to thrive. It’s a cyclical occurrence that when ticks have a “good” year, Lyme disease numbers tend to increase. With the global onset of environmental changes, though, the effects on the United States climate have been detrimental.
Consider the wildfires that rage through California. Although climate change may not be a direct cause, it is a threat multiplier, meaning that it increases the risk that such events will be worse than in previous years. But what does this have to do with tick populations and Lyme disease?
When extreme weather conditions change and deviate from normal patterns, ecosystems become disrupted. This can either spell disaster for a tick population or encourage a growth in numbers. When it comes to extreme weather this year, if part of the country is expected to see rising temperatures and milder winters, it gives ticks the opportunity to reproduce more rapidly and survive for longer periods of time – thus increasing the likelihood of Lyme disease transmission.
Does weather affect ticks?
Weather affects ticks like it would any other cold-blooded species. Since ticks cannot regulate temperature the same way warm-blooded creatures do, they need certain conditions to maintain life, as their bodies become the same temperature as the conditions they are put in.
In the event that a winter is especially harsh and cold, tick populations the following year will be lower. This is because cold enough temperatures will kill ticks, thus limiting their time to breed. In an opposite event where a winter is especially mild, ticks will have more time to survive and reproduce in larger numbers. This will cause a spike in tick populations the following season.
A tick’s ability to find a host, such as a deer, will also come into play during changing seasons, as they can take body heat away from the deer to survive for longer periods of time. Snow can also encourage tick survival; it acts as an insulator for ticks hiding underneath leaves and debris in wooded areas.
Do ticks like wet or dry weather?
Humidity plays a huge role in tick populations because they thrive in wet weather. When a summer is especially humid and the heat lingers well into the fall, tick populations for the following season become larger due to this climatic encouragement.
Humidity and heat also play a role in the life cycle and activity of other animals, some of which ticks use as hosts, giving them an even better chance at surviving for longer throughout the year. When animals are more active during warmer months and longer summers, they offer the perfect place for ticks to feed and breed.
How is climate change impacting the spread of Lyme disease?
Climate change has a direct effect on global tick populations, and since ticks are the spreaders of Lyme disease, it can spell bad news for those who explore the outdoors during the warmer months. When a larger geographical area becomes habitable for tick populations, they can spread across the United States, giving them more ground to cover and more hosts to latch on to.
This leads to an increased risk for catching Lyme disease because of the higher number of possible areas where infected ticks are able to thrive. With climate change and the increase in winter temperatures, ticks can also have longer life cycles, which then leads to higher populations and a higher susceptibility of infected tick contact.
Studies have suggested that the public health threat of Lyme disease will continue to grow in the United States as climate change becomes more prevalent, due to tick distribution throughout the country as well as the ability for ticks to live, feed, and breed longer. It is expected that higher tick populations will become a part of everyday life across the entire eastern side of the country due to climate change.
Lyme disease environmental factors
Climate change is not directly related to the onset of Lyme disease, because Lyme can only be contracted via tick bite. However, it plays a huge role in tick populations, which can lead to a surge in cases.
The 2020/2021 winter season is in a La Niña cycle, which means that winter weather is likely to be wetter than normal and could have more snow than usual. As mentioned, snow can act as an insulator for ticks to help them survive longer into the winter, thus improving their ability to procreate and increase their populations.
Tick populations and the prevalence of Lyme disease is so closely related to climate change that the United States Environmental Protection Agency has used Lyme disease numbers as a climate change indicator.
Extreme weather conditions will always play a direct role in tick populations, and when ticks have the proper ecosystem – warm weather that lasts long enough for them to go through their lifecycle and viable mammal hosts – they will continue to thrive and make their way around the forested areas of the country. When this happens, the risk of becoming ill with Lyme disease is higher because the opportunity for a tick to latch on to a human host is heightened. To battle the overabundance of Lyme disease-infected tick populations, climate change must be addressed.
Featured image by Erik Karits on Unsplash