Extension Notebook: Asian longhorned tick recommendations for livestock producers

By Teresa L Steckler

Since the U.S. Department of Agriculture confirmed the presence of the Asian longhorned tick (Haemaphysalis longicornis) in 2017, it has been spreading westward. It was first identified on a sheep in New Jersey and has since been identified in 19 states (USDA 2024): Arkansas, Connecticut, Delaware, Georgia, Indiana, Kentucky, Massachusetts, Maryland, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia and West Virginia. On May 6, 2024, official notification was made that Illinois is the 20th state to report the presence of ALT. The ticks were found in Morgan County.

The invasive tick species originates from east Asia. ALTs are light brown in color and very small, often smaller than a sesame seed, which makes them very difficult to detect. Adult females are only about the size of a pea when full of blood (fully engorged).

One major differentiating factor between this tick and those native to the U.S. is that ALT can reproduce parthenogenically — that is, no males are needed to fertilize the females. Thus, when ALTs find preferred habitats in new areas — low-lying swampy areas, wooded areas, and taller grasses — an established population can form and feed on wildlife, livestock, pets and humans.

Thus far, the ALT has been found on numerous domesticated and wildlife species hosts, including sheep, goats, dogs, cats, horses, cattle, chickens, black bears, grey squirrels, red and grey foxes, groundhogs, striped skunks, white-tailed deer, elk, opossums, black bear, raccoons, Canada geese, barred owls, great horned owls, brown boobies, mice, blue jays and red-tailed hawks (USDA, 2024).

All stages of the life cycle of the tick can be present on a single animal at a given time and, like native ticks, the ALT can carry pathogens that can cause disease in humans and livestock. On birds, the ticks can around the eyes of birds while on mammals they can be found around eyes, ears, brisket, udder, tail head/vulva areas and folds of skin.

In U.S. cattle, the known disease of concern thus far that can be transmitted by ALTs is Theileria (Theileria orientalis Ikeda strain; cattle theileriosis). Other species of Theileria (e.g. Chitose) have been present in the U.S. for years and can infect cattle, but they do not cause any clinical signs of disease. The presence of ALTs does not mean that they are carrying Theileria orientalis Ikeda strain. Theileria has been diagnosed in 10 states: Virginia, West Virginia, North Carolina, Tennessee, Kentucky, Pennsylvania, Maryland, New York, Missouri and Kansas.

Both Theileria orientalis Ikeda and the bacterium Anaplasma marginale cause infectious bovine anemia. Thus, Theileria will present clinically like anaplasmosis. Clinical symptoms of anaplasmosis include anemia, weak, lethargic, go off feed, fever and pale mucous membranes and possibly yellow from the waste products of red blood cell destruction. Mature

cattle are the most susceptible to severe clinical signs of anaplasmosis while cattle under six months of age generally show no signs. However, Theileria can affect all cattle regardless of age but pregnant heifers and calves are the most susceptible.

A blood test can determine if the animal has anaplasmosis or Theileria. There is no approved treatment or effective vaccine for Theileria and cattle that recover from initial illness become chronic carriers of disease. Just like anaplasmosis, routine husbandry practices can also spread Theileria.

Large numbers of ALTs have been found on domesticated animals (cattle and sheep) which can result in severe distress or even death through exsanguination. Tick control methods are even more important now that this tick has been found in Illinois. Below are a couple of items to keep in mind:

• Consult your herd veterinarian on appropriate herd health protocols and recommended products.

• Use pour-on external parasite control at the appropriate rates.

• When working livestock, look around the eyes, ears, below the tail and brisket areas for large numbers of small ticks.

• When purchasing livestock, regardless of whether in or out of state, or returning home from livestock shows, quarantine the livestock and treat with an external parasite control. Before turn-out, inspect the livestock for ticks.

• Keep pastures mowed in areas where the ticks have an established population.

• After pasture turn-out, livestock should be monitored frequently for the presence of ticks regardless of external parasite treatment. The length of time that any of these products will keep livestock from becoming reinfected is not currently known.

Lastly, protect yourself and pets from tick bites. Permethrins can be applied to clothing and last through washings. Note of caution: read the labels and do not spray permethrins or have any freshly treated clothes around pets. Check with your local vet on the appropriate products to protect your pets from ticks and fleas.

Teresa L. Steckler is a University of Illinois Extension specialist, animal systems/beef, Dixon Springs Agricultural Center.