The number of Americans catching diseases from tiny bloodsucking creatures is going up at an alarming rate, federal authorities warn. According to the latest report from the Centers for Disease Control and Prevention, the number of reported illnesses caused by ticks, mosquitoes, and fleas more than tripled between 2004 and 2016—and since many illnesses go unreported, the true total is probably much higher than the 642,602 cases reported over the period. In the case of Lyme disease, which is spread by ticks, the number of illnesses may be up to 10 times the 36,429 cases the CDC recorded for 2016, the Washington Post reports. Lyme and other tick-borne diseases like Rocky Mountain spotted fever accounted for 75% of what the CDC calls "vectorborne disease cases."
The CDC says tick-borne diseases—including recently discovered ones like Powassan virus—are on the rise in the Northeast, California, and the upper Midwest, the New York Times reports. Analysts say warmer weather, which is causing longer tick seasons and expanded insect ranges, has certainly played a role in the rise in infections, though there are certainly other factors: The increase in jet travel is helping disease spread more quickly than in the past, and the reforesting of suburban areas combined with the decline in deer hunting has created a good environment and an ample supply of hosts for the creatures. The Times has a guide on how to protect yourself from ticks and mosquitoes. Experts say it's a good idea to steer clear of downed logs and tall, grassy fields.