An exotic tick previously unknown to the United States is spreading across the eastern U.S. with sightings in eight states this summer.

The Asian or longhorned tick, Haemaphysalis longicornis, has been found in Arkansas, Maryland, New Jersey, New York, North Carolina, Pennsylvania, Virginia and West Virginia.

Native to East and Central Asia, the tick was thought to have been found for the first time in the U.S. after it was located on a farm in Hunterdon County, New Jersey, in November, but the U.S. Department of Agriculture's National Veterinary Services Laboratory recently confirmed a tick taken from a dog in Union County, New Jersey, in 2013 also was a longhorned tick.

An invasive species that congregates in large numbers, the longhorned tick can cause anemia in livestock. It is known to carry several diseases that infect hogs and cattle in Asia. So far, ticks examined in the U.S. do not carry any infectious pathogens.