Armies of clones of wild ticks are sucking cows; experts fear for humans

Voracious swarms of cloned ticks killed a fifth cow in North Carolina by exsanguination, that is to say by emptying her of blood, warned the Department of Agriculture and Wildlife Services. consumers of the state this week.

Experts fear that the bloodthirsty crowds, first noticed in the United States in 2017, continue to rampage, siphoning animal life and eventually transmitting life-threatening diseases to humans.

Last month, infectious disease researchers in New York reported the first case of tick specimens biting humans in the United States. The discovery was "not surprising" given the ferocious nature of the tick, according to Dr. Bobbi S. Pritt, director of the clinical parasitology laboratory at the Mayo Clinic. And it's "extremely disturbing for many reasons," she wrote in a comment for the journal Clinical Infectious Diseases.

The tick – the horned Asian tick, or Haemaphysalis longicornis– was first discovered terrorizing a sheep in New Jersey in 2017 and has established local populations in at least 10 states since its stealthy arrival. Its invasive impetus is due in large part to the fact that a single well-fed female can give birth up to 2,000 clones of ticks parthenogenetically, that is, without mating. in a few weeks. And unlike other ticks that tend to feast on victims for up to seven days, crowds of H. longicorni can take up to 19 days.

Bloody Blitz

According to the new report in North Carolina, the latest victim was a young bull in Surry County on the border with Virginia. At the time of his death, the condemned beast had over 1000 ticks on him. The official cause of death was acute anemia, usually associated with severe bleeding. The owner of the bull had lost four other cattle in the same way since 2018.

The case echoes the first report of the tick, which followed a lonely sheep in a wealthy New Jersey neighborhood in August 2017. The animal was besieged by hundreds of ticks, which inflamed the investigators' legs of health during their visit. the situation.

Since then, researchers from national veterinary laboratories have examined their tick samples and discovered a larval disease. H. longicornis was isolated from a whitetail deer in Tyler County, West Virginia, in 2010, backdating the first known case in the United States. However, researchers do not know when the tick arrived and where it came from.

H. longicorni as its nickname indicates, finds its origin in Asia, specifically in the east of China, Russia, Korea and Japan. In recent decades, it has spread to Australia, New Zealand and several Pacific islands, as well as the United States.

Infective bites

In China and South Korea, it is known that the tick spreads SFTSV, abbreviated virus of severe fever with thrombocytopenia syndrome. SFTSV is linked to the Heartland virus discovered in the United States and has reported mortality rates of up to 30%.

H. longicorni is also known to convey Rickettsia japonica, the cause of Japanese spotted fever, and Theileria orientaliswho is behind theileriosis of cattle. It has also been found in relatives of American pathogens, including those that cause anaplasmosis, ehrlichiosis, babesiosis and the Powassan virus. A flawless stay

So far, health investigators have found no ticks carrying these germs. But there is a risk that they can be introduced at any time, Dr Pritt notes. And, if they are, the diseases could easily spread like wildfire through voracious hordes of ticks.

The 66-year-old New York man who recorded the first H. longicorni the bite was healthy before and three months after the encounter. He found the tick on his right leg after working on his lawn and brought it to a Lyme disease diagnostic center, suspecting him of being at risk of contracting Lyme disease.

Although the tick tick is free of disease, when the investigators returned to the man's lawn and a nearby park, they easily found more ticks. More worryingly, ticks were hiding in a short, sunny grass, while other ticks in the area tend to stick to shady, wooded areas.

The authors note that "the findings of this survey suggest that it may be necessary to modify public health messages, at least in certain geographical areas, in order to focus on a broader range of health outcomes. potential habitats for ticks ".

H. longicorni populations exist in Arkansas, Connecticut, Kentucky, Maryland, New Jersey, New York, North Carolina, Pennsylvania, Virginia, and West Virginia.