Shingles isn't just a nasty and extremely painful experience. It can also cause strokes and heart attacks, researchers reported Tuesday.
They found elderly people who suffered a bout of the excruciating blisters were more than twice as likely to have a stroke in the first week after an attack started, and nearly twice as likely to have a heart attack.
Shingles, also called herpes zoster, is a souvenir of childhood chicken pox infection. Both are caused by the same virus, although it's called varicella when it causes chicken pox.
Like all herpes viruses, it stays in the body forever, moving along the nerves. Usually the immune system can control it after the first outbreak of chicken pox, but as people get older, or if they get cancer or another condition that depresses the immune system, it can erupt in a band of blisters.
About a million Americans suffer a shingles outbreak every year.
Unlike itchy chicken pox, however, shingles can hurt. And it can cause months of pain after the blisters heal.
Some studies had suggested that an outbreak of shingles might cause heart attacks, so Caroline Minassian and colleagues from the London School of Hygiene and Tropical Medicine looked at the medical records of more than 67,000 U.S. Medicare patients who had shingles and suffered either a stroke or heart attack within a year afterwards.
"We observed a marked increase in the rate of acute cardiovascular events in the first week after zoster diagnosis: a 2.4-fold increased ischemic stroke rate and a 1.7-fold increased MI (heart attack) rate," they wrote in the Public Library of Science journal PLoS Medicine.
"The most marked increase was observed during the first week following zoster diagnosis."
There are two possible causes, they said. The virus may be replicating inside the walls of the arteries, causing fatty buildups to break off and cause a stroke or heart attack. Or it might be the pain causing stress that sends the blood pressure up, they said.
Minassian's team was trying to see if vaccination might help, but hardly any of the patients in the study had been vaccinated. There are vaccines against both chicken pox, for kids, and shingles, for adults.
There's no cure for either but antiviral drugs can help. Everyone in the study was having a severe attack and was taking drugs. Milder cases that aren't bad enough to send someone to the doctor may not have the same risks, the researchers said.