MONDAY, MARCH 19, 2018

Black-legged ticks connected to encephalitis cases in New York state

Black-legged ticks, which are known for spreading Lyme disease, were linked to Powassan encephalitis in New York state, according to a study recently published in Parasites and Vectors.

Powassan encephalitis is a disease caused by the Powassan virus and the deer tick virus. The virus spreads from infected ticks and can cause encephalitis, meningitis and central nervous system disruption. Reported cases have a 10 to 15 percent fatality rate, and many survivors suffer long-term neurological damage.

"We've seen a rise in this rare but serious illness in parts of New York state that are hotspots for Lyme disease," Rick Ostfeld, one of the paper's authors, said. "And we suspected it was tied to an increase in black-legged ticks carrying deer tick virus, particularly on the east side of the Hudson River."

Researchers conducted a five-year assessment, examining more than 13,500 ticks of seven species. Areas east of the Hudson river had the highest concentration of deer tick virus-infected adult ticks, with four to five percent in Dutchess, Putnam and Westchester counties. The researchers determined that raccoons, striped skunks and Virginia opossums were most likely to transmit deer tick virus to feeding ticks.

Deer tick virus transmission can occur in just 15 minutes, highlighting the need to be vigilant in tick habitats.

"When patients present with encephalitis symptoms in areas with high levels of Lyme disease, especially during the summer, physicians need to consider Powassan encephalitis," Ostfeld said. "While rare, it's associated with significant complications. There is no vaccine or specific antiviral therapy, the best strategy remains prevention."