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Scientists from the National Institutes of health have developed a laboratory model to study ticks that transmit flaviviruses — a class of viruses that includes Powassan virus, which was implicated in the death of a New York man earlier this year.
Most people are more familiar with flaviviruses spread by mosquitoes — including Zika virus and West Nest Vile — but they are also the cause of at least two tick-borne diseases, Powassan and the closely related deer tick virus. Lyme disease is still the star scourge among tick-borne diseases, but another, Powassan virus, has been making itself known.
In the last 10 years, about 75 U.S. cases of Powassan virus infection have been reported, according to the Centers for Disease Control and Prevention. Those include at least one case in Connecticut, last year in a 5-month-old child. Powassan virus infection can result in fever, headache, vomiting, weakness, confusion, seizures, memory loss, and death. No licensed treatments or vaccines are available for Powassan virus disease.
The scientist’s unusual model for studying ticks that spread flaviviruses involves culturing organs taken from Ixodes scapularis ticks and then infecting those organ cultures with flaviviruses, according to researchers at Rocky Mountain Laboratories, part of NIH’s National Institute of Allergy and Infectious Diseases. The researchers said model could become a tool to evaluate medical countermeasures against tick-borne viruses.
The NIAID scientists developed their model by dissecting three tick organs — the midgut, salivary glands and nervous tissue — and then culturing flaviviruses in those organs, evaluating their viability over several days. They found that Powassan virus and the related Langat virus could infect and spread in salivary glands and midgut. Langat virus is found typically in Southeast Asia and is an ideal model virus for study because it causes only rare, mild infections in people.