Cases of disease acquired from ticks, mosquitoes and fleas have more than tripled in the United States in the last 13 years, according to a new study by the Centers for Disease Control and Prevention.
The study, conducted by the CDC and released on Tuesday, looked at vector-borne diseases, or illnesses transmitted to humans by blood-sucking ticks and other insects, from 2004 through 2016. Of the 642,602 total cases reported to the CDC during the 13-year study, the number of cases rose most years, more than tripling from start to finish. In 2004, there were 27,388 total cases of vector-borne diseases reported, compared with 96,075 in 2016.
Dr. Lyle Petersen, director of the Division of Vector-Borne Diseases and one of the authors of the study, told CNBC on Wednesday that the rise in numbers was attributed to three things: increased global travel and trade, environmental changes and a lack of prevention efforts.
In the case of Lyme disease, which costs approximately $492 million annually in diagnostic testing and accounts for 82 percent of tick-borne diseases, Petersen said reforestation, or the process of replanting an area with trees, has contributed to the problem.
Reforestation "has allowed deer populations to explode, which has caused ticks to also explode in number, which has caused an increase in Lyme disease," Petersen said Wednesday on "Closing Bell." "And more people live around these deer now, where they're at risk."
The number of actual bugs, specifically ticks, has also increased dramatically over the course of the study, Petersen said.
"Some of the increase is due to the fact that we've been able to identify and diagnose more of these diseases," he said.
Vector-borne diseases are passed to humans by way of pathogens — bacteria, viruses and parasites — which lead to illnesses. In the U.S., the most common vector-borne pathogens are transmitted by ticks or mosquitoes. The number of mosquito-borne viruses was widely dispersed throughout the country, but tick-borne illnesses were found predominantly in the Eastern part of the U.S.