A 5-week-old baby in Boston is fighting for her life after a tick bite.
The baby, Lily Sisco, was bitten while on a walk with her family on Martha’s Vineyard, her mother, Tiffany Sisco, told local news outlets.
After returning from the walk, Sisco told WCVB Channel 5 Boston, "I found this tiny, tiny, tiny, the teeniest [tick] on her ankle."
"I picked it off, and like, a week later, she started getting a fever of 102."
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The Siscos brought baby Lily to the emergency room, and she was then flown to Massachusetts General Hospital in Boston for advanced care, according to a GoFundMe page set up for the family.
In addition to the fever, the baby began to experience seizures, which led to her placement in the PICU (pediatric intensive care unit).
The Siscos shared in the GoFundMe that Lily "has suffered brain damage caused by an infection."
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"She is being monitored daily on large doses of seizure medication to reduce further damage … We remain at MGH with 24 hours monitoring with some of the best doctors in the world."
Health officials believe that Lily Sisco’s illness may have been caused by Powassan virus, which is transmitted by the bite of an infected deer tick, according to a press release from the local health department.
Dr. Marc Siegel, Fox News' senior medical analyst, said the Powassan virus is transmitted much more quickly than Lyme disease, with an incubation period of one to four weeks.
While cases are rare, with just seven to eight diagnoses each year in the U.S., they have been on the uptick in recent years — primarily in the Northeast and Great Lakes regions, according to the U.S. Centers for Disease Control and Prevention (CDC).
Other than this possible case, there has only been one confirmed Powassan virus infection on Martha’s Vineyard in the past 20 years.
Three cases have been confirmed state-wide this year, per CDC data.
"The virus is present every year in a small percentage of deer ticks; fortunately, severe disease remains very rare," said Dr. Sam Telford, Tufts University professor with longstanding research on Martha’s Vineyard, in the press release.
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Telford’s lab has tested more than 3,500 nymph deer ticks (in their second life stage) between 2021 and 2024, the release stated, finding that between 1% and 2% of nymph deer ticks on Martha’s Vineyard are infected.
"This suggests that many people who are exposed may successfully fight off the virus without ever knowing they were infected," Telford said.
Nymph deer tick are most active on Martha’s Vineyard from May through July, according to Patrick Roden-Reynolds, director of the Martha’s Vineyard Tick Program.
"Their activity coincides with when we spend most of our time outdoors and, unfortunately, when our island population grows for tourism season," he said in the release.
These ticks are the main driver of not only Powassan virus, but also Lyme disease, babesiosis, anaplasmosis and borrelia miyamoto.
"Although nymph deer tick activity typically slows in August and September, adult deer ticks become active in the fall and remain so throughout the winter and early spring whenever temperatures exceed 40°," Roden-Reynolds added.
Initial symptoms of Powassan virus include fever, headache, vomiting and weakness, per the CDC, although some infected people may not get sick.
In some cases, the virus can lead to severe illness, leading to inflammation of the brain and spinal cord.
In these rare cases, those infected may experience difficulty speaking, confusion, loss of coordination and seizures, the health agency warned.
While anyone can develop severe disease, those at highest risk include older adults, children and people who are immunocomprised.
There are no vaccines available for Powassan virus.
"Unlike most tick-borne illnesses, 10% to 15% of severe cases are fatal, and half of the survivors experience permanent neurological damage," Dr. Jorge P. Parada, M.D., medical advisor at the National Pest Management Association (NPMA) in Chicago, told Fox News Digital.
Many who experience severe disease suffer from long-term symptoms, including headaches, memory problems and a decline in muscle strength.
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There is not a specific medication for Powassan virus, with treatment focused on managing symptoms and complications.
The most effective way to keep Powassan virus and other infectious diseases at bay is to prevent tick bites, experts agree.
Prevention strategies include using EPA-registered insect repellents containing at least 20% DEET, wearing light-colored clothes with long sleeves and pants tucked into socks in areas with ticks, and performing a thorough tick check on yourself, your family and pets after being outdoors, according to Parada.
"We also recommend making your yard less attractive to ticks by keeping grass short, and using gravel or wood chips to create a ‘tick moat’ between the edge of your property to discourage migration," he advised.
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The doctor added, "The combination of Powassan’s rapid transmission, severe health consequences and lack of treatment options makes this an emerging public health concern that requires immediate attention to prevention efforts."