A House amendment to national defense legislation is raising alarm about the rates of cases of Lyme Disease in the United States, but it may also lead to a few raised eyebrows. Lyme disease is definitely a threat in the northeastern United States. Across the country in 2017, there were a record-breaking number of cases of tickborne illnesses reported.

The threat of Lyme disease is real, but we’re not so sure about the amendment to the 2020 National Defense Authorization Act ordering that the Pentagon investigate if the Department of Defense weaponized Lyme disease in ticks in the 1960s. While I can neither confirm nor deny the existence of a covert Cold War program to impose rashes, stiffness, and joint pain in America’s enemies, numerous articles disprove this theory.

Explanations instead point to evidence that Lyme disease pre-dated the arrival of Europeans , probably by tens of thousands years. The amendment does, thankfully, include $1 million for the Center for Disease Control (CDC)’s budget for Lyme disease, critical research needed to help diagnose, treat, and prevent Lyme disease. This helps to close the gap in funding for Lyme research discussed in a U.S. Department of Health and Human Services report that found each new case of Lyme disease receives 2 percent or less than the funding per new case of  HIV/AIDS and hepatitis C.  Lyme disease mostly affects the Northeast and Midwest, with cases occurring across the country and other tick-borne illnesses affecting almost every region.

Beyond the biological weapon “theory,” there are some much more compelling explanations for the explosion of Lyme Disease and other tickborne illnesses, and also shed some light on why seven new tickborne germs have been identified in the past two decades.

Unsurprisingly, climate change plays a part. Ranges of the lone star tick have expanded beyond the southeastern United States and the number of counties nationwide with blacklegged deer ticks (largely responsible for Lyme Disease) have doubled in the past twenty years. These changing ranges are related to development patterns (urban sprawl increasingly puts people in contact with wild areas) and deer or other carrier populations. But climate patterns and changes in seasons are also having their impact.

Lyme disease and changes in the climate are so closely linked that the U.S. Environmental Protection Agency (EPA) uses Lyme disease as a climate change indicator. As the EPA explains, the life cycle and prevalence of deer ticks are influenced by temperature. They are most active when temperatures are above 45 degrees F and with at least 85 percent humidity. Warming temperatures are transforming more of the country into a comfortable environment where ticks can thrive. Additionally, warmer winters are allowing ticks to survive, and even stay active in the winter. The explosion of winter ticks in the Northeast has been blamed for declining moose populations where ticks can drain so much blood that moose become anemic, malnourished, and younger moose will die as was reported last year in Scientific American.