“Not every tick immediately transmits pathogens,” Kahl emphasizes. Depending on the region, five to 35 percent of all ticks are infected with Borrelia. In some areas, the number can be even higher.

At a more micro level, the top five tick-infested cities in the U.S., in descending order, are New York City, Los Angeles, Philadelphia, San Francisco and Washington, D.C., according to the report.