An invasive tick species native to East Asia has now been documented in six states on the East Coast and one in the Midwest. Various local, state, and federal health experts continue to investigate how the Asian longhorn tick (Haemaphysalis longicornis) entered the country, its current range, and possible threats to public health.
It started last summer after a woman found hundreds of ticks on her pants, hands, and wrists after shearing her pet Icelandic sheep. The animal had no history of travel outside of the country and hadn’t traveled locally for several years. Investigators, who published their findings in a report earlier this year in the Journal of Medical Entomology, reported that the sheep’s paddock was so invested with ticks that their pants were soon covered in all three life stages of the tick.
Longhorn ticks have been found on local livestock and wild deer, but DNA analysis has not yet confirmed infectious pathogens that cause six of the most common tick-borne diseases, including Lyme disease, babesiosis, relapsing fever, anaplasmosis, two forms of ehrlichiosis. However, it is possible they can transmit other local diseases like Rocky Mountain spotted fever. In their native East Asia, longhorn ticks are known to carry a pathogen responsible for severe fever with thrombocytopenia syndrome (SFTS) – an illness with a fatality rate as high as 30 percent.
For now, the biggest threat is to livestock. After feeding, females reproduce asexually and can lay as many as 2,000 fertile eggs without mating. Three of the first confirmed cases appear to have all been the offspring of an original female. If enough ticks attach themselves to an animal, it’s possible the loss of blood can kill it.