By Melissa Mayer

Scientists think ticks could be up to 300 million years old. The fossil record even includes amber-encased ticks still engorged with their last dino meal.

Which is amazing. Those blood-sucking arthropods have been doing their thing for longer than humans have existed—and their thing includes carrying disease. Ticks are responsible for more than 75 percent of the vector-borne illnesses reported to the U.S. Centers for Disease Control and Prevention (CDC) every year. The most common of these is Lyme disease with 30,000 to 40,000 annual reported cases—though the CDC estimates the actual number of cases, most of which go unreported, could be more than 400,000 annually.

A team of CDC researchers recently constructed the first map to reveal county-level distribution of host-seeking vector ticks carrying the bacteria that causes Lyme disease. The team from the Bacterial Diseases Branch of the National Center for Emerging and Zoonotic Infectious Diseases reported their findings this month in the Journal of Medical Entomology.

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