Overview

• Lily Sisco, a newborn from West Tisbury, is critically ill at Massachusetts General Hospital with encephalitis but has begun to show gradual neurological improvement after contracting Powassan virus.
• The Martha’s Vineyard Boards of Health confirmed it as the island’s second Powassan case in 20 years and the fourth in Massachusetts this year, prompting local investigations into exposure sources.
• Powassan virus is transmitted by deer ticks within 15 minutes of a bite, can cause severe brain inflammation and seizures, and has a fatality rate of roughly 10% with no specific treatment or vaccine.
• Emergency department visits for tick bites in the Northeast are at a five-year high, driven by milder winters and expanding deer populations that increase human–tick encounters.
• Public health agencies are urging year-round tick-bite prevention measures such as using EPA-approved repellents, treating clothing with permethrin, performing daily tick checks, and staying on clear trails.