Shingles is caused by the varicella-zoster virus, which also causes chickenpox and can reactivate later in life. The risk for stroke remains elevated for a year after the painful rash of shingles disappears, say researchers from the University of Colorado Anschutz Medical Campus.

Andrew Bubak, assistant research professor in the department of neurology at the University of Colorado School of Medicine, investigated the mechanism behind the increased stroke risk and found that exosomes — tiny sac-like structures formed inside cells that contain some of the cells’ DNA and RNA — travel through the blood to other parts of the body and can cause inflammation and thrombosis away from the site of actual infection. 

“That could ultimately lead to a stroke in patients,” he said.

Bubak and his team collected plasma samples from 13 patients with shingles and 10 without to extract exosomes from the plasma. They discovered prothrombotic exosomes, which can lead to blood clots, in the plasma of the patients with shingles.

And at a three-month follow-up they also found proinflammatory exosomes in the patients, which also carry a risk for stroke.

The findings suggest that in some people with shingles, the virus doesn’t return to its latent state or the exosomes that cause the prothrombic state survive therapy for the disease.

Bubak suggested that using antiviral agents longer may help, along with the addition of antiplatelet and anti-inflammatory medications.