Scientists find more evidence of Powassan virus in tick sample
An estimated 6 percent of ticks collected in a large sample north of Long Island carried a pathogen known as the Powassan virus, an emerging infectious agent and yet another microbe transmitted by the insidious creatures.
The belly of a tick can serve as home to a veritable microbial zoo, scientists say.
Powassan virus is important, scientists said Wednesday, because it's helping to provide context to the many species of microbes that ticks carry -- and the diversity of diseases these infectious agents cause.
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"The more ticks you study, the more you will find Powassan virus," said Dr. Jorge Benach, a professor of molecular genetics and microbiology at Stony Brook University School of Medicine.
Last month, medical investigators reported on the emergence of Borrelia miyamotoi, a newly discovered tick-borne bacterium that causes relapsing fevers, an infection that initially can be easily confused with Lyme disease.
The Powassan virus, by comparison, has been in the country since 1958 but only recently has begun to become more evident. In a sample of 13,000 ticks collected by state Health Department scientists in the Hudson Valley and suburbs north of New York City, they found that 6 percent carried the virus. The viral name is derived from a Canadian town in Ontario, home to a young boy in the 1950s who was infected and died.
While some people do not develop symptoms from the virus, it can cause encephalitis and is related to microbes that cause other summertime infections, Benach said.
There was one serious case in Saratoga so far this year, according to the state Health Department. Another in 2009 in Suffolk County was dismissed as having been transmitted on Long Island because health authorities traced the patient's infection to another state. Five people have died in New York of the mysterious virus since 2004.
Sen. Charles Schumer (D-N.Y.) on Wednesday called on the Centers for Disease Control and Prevention to allocate resources toward the study, prevention and treatment of the Powassan virus because Long Island and surrounding areas lead the state in tick-borne illnesses.
"This virus goes into your bloodstream within 15 minutes and it doesn't leave a telltale mark, so there's a desperate need to educate the public and physicians," said Schumer, who was bitten by a tick a few years ago as he walked in high grass in Dutchess County.
Benach, who in the '80s helped discover the Lyme disease bacterium, said ticks that carry Powassan virus seem not to infest deer but are often isolated on mice and other small animals.
"Powassan in our area is mostly related to ticks and woodchucks," Benach said of the major mammalian carrier of the so-called common deer tick. "Powassan is similar to the viruses that cause West Nile and St. Louis encephalitis."
But he and other experts Wednesday noted that cases have oscillated -- waxed and waned -- in recent years.
"Interestingly, many people who get Powassan virus are asymptomatic," said Lauren Barlow, a nurse epidemiologist with the Suffolk County Department of Health.
TICKS AND INFECTIONS
Ticks can transmit diseases caused by viruses, bacteria and protozoa. The latter are the kinds of microbes that cause malaria.
Lyme disease, which is bacterial, is the most common tick-transmitted infection.
Powassan virus rarely causes symptoms. People can be infected but not know it.
When Powassan virus does cause serious infection, it leads to encephalitis.
In wooded areas, medical experts recommend wearing shirts with long sleeves and pants with long legs to help thwart tick bites.
The black-legged or deer tick is carried by mice, squirrels, woodchucks and deer, among other mammals.
Source: New York State Department of Health; Suffolk County Department of Health