Asian Longhorned Ticks Spread to New Illinois County

By Andi Anderson

The invasive Asian longhorned tick has been detected in Clay County, Illinois, marking the third county in the state where this species has been confirmed since its first appearance in 2024.

The discovery came through a community-engaged surveillance program that encourages the public and livestock producers to submit ticks for identification.

Cattle from Clay County were inspected at a Marion County collection station as part of this monitoring effort. Experts at the Illinois Natural History Survey Medical Entomology Lab identified the ticks, and the USDA National Veterinary Services Laboratory confirmed the presence of adult female Asian longhorned ticks.

According to specialists, the frequent sale and movement of cattle between farms and states play a key role in the spread of this invasive pest.

“The discovery of the invasive tick in another county shows that the pest is on the move across the state,” said Teresa Steckler, commercial agriculture specialist with University of Illinois Extension. She advised residents and livestock owners to stay vigilant and take precautions to protect themselves and their animals from tick bites.

Asian longhorned ticks reproduce asexually, allowing them to establish quickly in new areas and rapidly grow in numbers. Their bites can lead to reduced growth and significant blood loss in livestock.

The species can also transmit Theileria orientalis, a protozoan parasite. While native strains in the United States are typically harmless, the Ikeda genotype causes bovine infectious anemia, a disease that weakens cattle with symptoms such as anemia, jaundice, and fatigue.

This genotype has already been detected in multiple states, including Iowa, Missouri, Indiana, and Kentucky.

Experts urge anyone who finds a tick on an animal or person to remove it immediately with tweezers and wash the area with soap and water.

This surveillance effort is a partnership between Illinois Extension and the Illinois Natural History Survey, with support from USDA NIFA and the Illinois Lyme Association, to help protect livestock and communities across the state.

Photo Credit: istock-fotokostic