The number of people in the United States infected by mosquito, tick, and flea-transmitted diseases have tripled, increasing from 27,388 cases in 2004 to 96,075 in 2016, according to a new report from the Centers for Disease Control. Since 2004, nine insect-borne diseases have also been discovered or introduced into the U.S., seven of which are carried by ticks.
In total, more than 640,000 cases of mosquito, tick, and flea-borne diseases were reported to the CDC between 2004 and 2016. Infections spiked in 2016, increasing 73 percent from 2015, due to the Zika epidemic. Cases of Lyme disease doubled from 2004, with 36,429 reported cases in 2016. Lyle R. Petersen, the CDC’s director of vector-borne diseases, however, told The New York Times the numbers for Lyme are likely far larger. The CDC estimates 300,000 Americans that get Lyme disease every year, nearly 10 times the number of diagnoses reported.
The new report does not mention climate change or global warming, but Petersen told Reuters that warmer, shorter winters have helped boost the populations of ticks, mosquitos, and other disease-carrying insects in recent years. “It enables these ticks to expand to new areas. Where there are ticks, there comes diseases,” he said. In addition, increasing summer temperatures and heavy rain events that leave behind standing pools of water encourage mosquito breeding. Other factors include increases in the number of people traveling internationally, suburban reforestation, and a lack of new vaccines being developed.