Man's brain 'blew up' after contracting this tick-borne virus—and more cases are expected this summer
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"It's important to know about because severe symptoms associated with it can be life threatening. So 1 out of 10 people who get the tick-borne virus end up with encephalitis or meningitis, which is an inflammation of your brain and or your spinal cord, which in itself can be life-threatening." — Zain Hasan, MD, anesthesiologist
Summer is upon us, and with it—tick season.
Last year, Massachusetts resident Kevin Boyce, 62, was hospitalized with a severe case of Powassan virus (POWV) encephalitis, which he contracted via tick bite.
Boyce died a week later after suffering brain damage from the disease—and the way his family members describe his symptoms serves as a chilling reminder of why it's important to counsel patients on how to stay safe during the warmer months.[]
Powassan virus: An overview
POWV is a neurotropic flavivirus transmitted primarily by Ixodes scapularis ticks, the same vector responsible for Lyme disease.
Unlike Borrelia burgdorferi, which typically requires 24–48 hours of tick attachment for transmission, POWV can be transmitted in as little as 15 minutes.
This rapid transmission window poses significant challenges for prevention.
Related: New tick-borne illness is deadlier than Lyme diseaseClinical presentation and outcomes
Boyce's initial symptoms—headache, vomiting, and flu-like manifestations—progressed rapidly to severe encephalitis. Despite intensive care, he suffered extensive brain damage and passed away weeks later.
Severe POWV infections can lead to encephalitis or myelitis, with approximately 10% of cases resulting in fatality and about half of survivors experiencing long-term neurological sequelae.
Speaking with CBS News, Boyce's sister described the horrific symptoms her brother experienced due to the disease: "His brain had blown up so much... and he had really bad brain damage," Erin Boyce said.[]
In a TikTok video, anesthesiologist Zain Hasan, MD, spoke on the significant risks associated with POWV: "It's important to know about because severe symptoms associated with it can be life threatening. So 1 out of 10 people who get the tick-borne virus end up with encephalitis or meningitis, which is an inflammation of your brain and or your spinal cord, which in itself can be life-threatening."
Epidemiological trends
While historically rare, POWV cases have been on the rise. In 2024, the United States reported 54 cases, with 12 occurring in Massachusetts alone. As of June 3, 2025, only 1 case of neuro-invasive POWV has been recorded in the US so far (Wisconsin), but experts are predicting a rise in cases as summer progresses, primarily due to climate change-related factors.[]
Related: A malaria-like disease is creeping through some parts of the US—and you might be missing it