DES MOINES, Iowa – Less than two weeks after the first case of Theileria in Iowa was confirmed in a Van Buren County cattle herd, the Iowa Department of Agriculture and Land Stewardship confirmed the second positive detection of the disease June 24. Both cases were in southeast Iowa.

“Theileria orientalis Ikeda is a protozoan parasite carried by the Asian Longhorned Tick (ALHT),” said State Veterinarian Jeff Kaisand in a June 13 media statement after the state’s first confirmed case of Theileria.

“The parasite infects red and white blood cells, and causes bovine infectious anemia,” he added. “According to USDA records, this is the first time Theileria and the ALHT have been confirmed in Iowa. There are no approved treatments for Theileria in the United States.”

Grant Dewell, Iowa State University associate professor of veterinary medicine and beef extension veterinarian, said in a June 13 media statement, “Although the tick will be active all summer, it is common to see a surge of infestations when cattle are first introduced into a new pasture. The presence of a preferred host generates a surge in new ticks, as females will begin to lay thousands of eggs.

“Cattle producers should closely observe cattle on pasture regularly for signs of tick infestation, especially in southern Iowa, although expect the tick to spread north this summer, particularly since many cows have been turned out to pasture recently,” he added.

He said, typically, cattle affected by Theileria will show signs of lethargy, anemia, and difficulty breathing, and may develop ventral edema, exercise intolerance, jaundice and miscarriages.

“Although signs of Theileria are similar to anaplasmosis, often younger animals and calves can have more severe signs, compared to mature cows and bulls,” he said. “Due to anemia from both tick infestation and Theileria, death loss can be elevated.”

In the first reported case of the disease, about 20 percent of cows in the 100-head herd died from it, he told The Cedar Rapids (Iowa) Gazette, which reported the information June 24. However, he added it’s typically not as fatal.

He also told The Gazette the tick’s movement throughout Iowa is likely due to the movement of deer that carried the tick. However, he said he doesn’t anticipate the infection becoming too widespread throughout Iowa.

Dewell told Farm World, “Theileria can be a problem, but expect it to stay fairly localized to southern Iowa. With as much as we move livestock, we could see it spread more, but naturally, it shouldn’t spread too fast. We have seen some death loss in a few of the herds. Expect that to decrease over time as immunity increases. Enhanced tick control and making sure cattle are in good nutritional status will help them if they are exposed.

“Be aware when moving into new pastures as ticks could be waiting for new hosts, and we get a bloom of new ticks and severe infestations of cattle, which is what we have seen these last few weeks,” he added.

He said, “Producers should be regularly checking cattle on pasture, looking for increases of ticks, or cattle that are becoming lethargic because of anemia. Contact your veterinarian if you notice any of those conditions.”

Dewell added, “Cattle producers should be aggressive with external parasite control this summer. Insecticide ear tags alone are not enough to control ticks. Consider adding a backrubber or regularly applying a pour-on during the summer.

“There are some pyrethroid-based products that have a tick control label,” he said. “If you see an increase in tick infestations, an avermectin (that has anti-parasitic and insecticidal properties) pour-on may be the best intervention.”

Although Theileria and ALHT can be detrimental to cattle, there is no health risk for humans, he added.

Kaisand said the best way to protect livestock is through tick control methods and proper biosecurity to prevent blood-borne spread between livestock.

“Veterinarians should include Theileria among the list of differentials for livestock displaying these clinical signs,” he said. “Veterinarians should collect appropriate samples and submit them to Iowa State University Veterinary Diagnostic Laboratory (in Ames) for diagnosis.”