A 5-week-old baby girl is clinging to life in a Boston hospital after a tick bite led to a rare but dangerous brain infection. Her story is now bringing national attention to the deadly Powassan virus, an emerging tick-borne threat with no vaccine, no treatment—and devastating consequences.

Lily Sisco was on a family walk on Martha’s Vineyard when her mother, Tiffany Sisco, noticed a tiny tick on the infant’s ankle. A week later, Lily developed a 102-degree fever. Within days, she was suffering seizures and had to be rushed to Massachusetts General Hospital, where doctors placed her in the pediatric intensive care unit.

According to a family statement on GoFundMe, Lily has “suffered brain damage caused by an infection” and is on high doses of seizure medication. Doctors are working around the clock to stabilize her, but the virus suspected of causing her condition—Powassan—is notorious for moving fast and hitting hard.

Unlike Lyme disease, which can take 24–48 hours to transmit from a tick bite, Powassan can infect a person in just 15 minutes. With an incubation period of just 1 to 4 weeks, this virus often gives little warning before progressing to serious neurological symptoms.

Fox News senior medical analyst Dr. Marc Siegel emphasized how rapidly the virus spreads. “It’s much more aggressive than Lyme,” he warned.

The Centers for Disease Control and Prevention (CDC) reports only a handful of Powassan cases each year—usually 7 to 8—but the number has been growing, especially in the Northeast and Great Lakes regions. This year, there have already been three confirmed cases in Massachusetts, where Lily lives.

The virus is spread by deer ticks, the same species that transmits Lyme disease and other infections like babesiosis and anaplasmosis. Nymph deer ticks—small and difficult to spot—are especially active from May to July, aligning perfectly with summer outdoor activity.

Dr. Sam Telford, a Tufts University professor who’s led years of tick research on Martha’s Vineyard, confirmed that 1–2% of nymph ticks on the island carry Powassan virus. He noted that many exposed individuals may fight off the virus without symptoms, but vulnerable populations—including infants—are at extreme risk.

Severe Powassan virus cases are rare but extremely dangerous. The CDC warns that 10% to 15% of severe cases are fatal, and half of survivors suffer permanent neurological damage. Symptoms can escalate from headache and vomiting to confusion, speech problems, seizures, and long-term disability.

“There’s no vaccine and no direct treatment for Powassan,” said Dr. Jorge Parada, a medical advisor at the National Pest Management Association. “We’re seeing a growing public health threat that most people still don’t know exists.”

Doctors say prevention is the best line of defense. Recommended strategies include:

• Wearing long sleeves and pants in tick-prone areas
• Using EPA-approved insect repellent with at least 20% DEET
• Performing full-body tick checks after outdoor activities
• Creating a “tick moat” in your yard with gravel or wood chips
• Keeping grass trimmed and reducing brushy areas

Lily’s condition has sparked an outpouring of support as her family remains by her side. “She’s fighting,” her mother said. “She has some of the best doctors in the world watching over her.”

Her heartbreaking story is a chilling reminder that even the smallest tick can carry catastrophic consequences. As outdoor recreation spikes in late summer and fall, public health officials are warning Americans to stay vigilant—and take every tick bite seriously.