Invasive longhorned ticks were just recently found in Boone County, Missouri, by researchers at the University of Missouri College of Veterinary Medicine. The discovery of the longhorned tick, which has already cost livestock producers globally millions of dollars in lost agricultural income, portends a potential future issue for the welfare of cattle in central Missouri.
Longhorned ticks, also known as Haemaphysalis longicornis, are a species of tick that is native to East Asia. They have been a topic of concern in recent years due to their invasive nature and potential impact on public health, livestock, and wildlife. Additionally, this species of tick may expose humans to a number of infections.
“These longhorned ticks have the potential to transmit theileriosis, a disease that kills red blood cells in cattle,” said Rosalie Ierardi, a clinical instructor at the MU Veterinary Medical Diagnostic Laboratory (VMDL) and doctoral student at the MU College of Veterinary Medicine, who last year discovered these same longhorned ticks in northern Missouri. “Symptoms of this infection in cattle could include weight loss, tiredness, weakness, jaundice and pregnancy loss, which all have economic consequences for cattle ranchers looking to sell their calves.”
Ram Raghavan, an associate professor in the MU College of Veterinary Medicine and an associate professor in the MU College of Health Sciences, is lerardi’s mentor. He made the finding in Boone County in late April. The recent discovery is part of Ierardi’s doctoral dissertation studies.
The invasive longhorned tick was discovered outside of quarantine in the United States for the first time in New Jersey in 2017 after being initially discovered in eastern Russia and Australasia, which is made up of Australia, New Zealand, and nearby islands in the Pacific Ocean.
These longhorned ticks have the potential to transmit theileriosis, a disease that kills red blood cells in cattle. Symptoms of this infection in cattle could include weight loss, tiredness, weakness, jaundice and pregnancy loss, which all have economic consequences for cattle ranchers looking to sell their calves.
Rosalie Ierardi
Since then, they have spread throughout the Mid-Atlantic, New England and Midwestern regions, being officially detected in at least 19 states and counting.
“These discoveries help raise awareness for both veterinarians and Missouri livestock producers so that they can monitor the health of animals and make better informed decisions,” Raghavan said.
“A combination of factors, including increasingly warming temperatures for ticks to thrive in and an increase in people engaging in outdoor activities in rural or suburban areas where ticks are more prevalent, have increased the rates of ticks transmitting pathogens to wildlife, people and their pets.”
Longhorned ticks can lay thousands of eggs asexually, or without the aid of a male, whereas the majority of ticks reproduce sexually, which makes it simpler for this species to establish itself fast in new locations.
Raghavan, who has a strong background in public health, has been monitoring the expansion of different tick species in the United States for 16 years. He made projections about the longhorned tick’s possible geographic distribution in a 2019 study, and so far, those forecasts have come true.
“The University of Missouri is a land-grant institution, and we remain committed to assisting Missouri veterinarians and Missouri cattle ranchers as they continue to monitor the health of their animals,” Raghavan said.
“Unfortunately, it appears that these longhorned ticks are here to stay, and the more vigilant we can become in monitoring the situation as it worsens going forward, the better prepared we will be. We need to monitor these ticks long-term throughout the central Midwest, where critical information about the biology of ticks in general is lacking.”
Ierardi and Raghavan encourage Missouri livestock producers who notice weakness, tiredness, jaundice or pregnancy loss in their cattle to contact their local veterinarian or the MU VMDL for assistance with tracking down the causes for such signs.
