The number of people who got a disease from mosquitoes, ticks or fleas more than tripled from 2004 to 2016, according to the Centers for Disease Control and Prevention.
There are several reasons for that trend, but experts say one main driver is the Earth's warming climate. And that's spelled trouble for the U.S., which has seen longer and longer warm seasons and higher temperatures in the past 15 years.
Insects that carry illnesses are thriving in these extended warm periods. Mosquitoes are very heat-sensitive and actually mature faster in warm weather. This also helps the viruses they carry develop even faster and can lead to an increased number of bites.
Metro Health Department spokesperson Brian Todd says one of the main worries is Rocky Mountain Spotted Fever, which is spread through tick bites. It causes rashes and flu-like symptoms.
"There are definitely diseases that are a threat and they're a threat to us," said Todd. "That's why we recommend people take steps if they're going to be outside to protect yourself."
Those steps include wearing long pants out into areas with ticks, applying bug spray and checking yourself thoroughly after outside activity.
As the U.S gets hotter, more and more areas are becoming suitable for mosquito and tick development. Part of the uptick in Lyme disease is linked to northerly expansion ; many areas that were once too cold for ticks are now perfect for them.
The CDC says to curb these rates, a crucial step is more funding for local health agencies who fight the disease firsthand. The CDC says 84 percent of mosquito control agencies said they didn't have the resources to properly track and control disease outbreaks.