It’s rare, but scores or even hundreds of outbreaks have been recorded through the decades around the world.
It’s a diagnosis that’s often reached after other causes are ruled out, and is usually traced to a stress-causing trigger. Individual cases are common, even the kind involving tics and other movement-related symptoms. On average, the National Institutes of Health gets reports of two such cases each week, said Dr. Mark Hallett, who heads the branch that fields those calls.
Outbreaks, however, are unusual. Most involve females, often teenagers. Why is not clear. Some think it has to do with the way girls are socialized to deal with stress. Others say that females are just more likely to seek medical help — and thus appear in medical reports.
Symptoms seen in outbreaks vary, and cases have included blindness, headaches, nausea, paralysis and inability to speak. As in infectious disease outbreaks, they often seem to begin with one person who gets the symptoms and then it spreads to people she knows. Experts believe that these first “index’’ cases often are people who have symptoms caused by a physical illness, but subsequent cases are subconscious mimicry.
Recent examples include:
—In the fall of 2007, at least eight girls at a Roanoke, Va., high school developed strange twitching symptoms similar to those in upstate New York. The school district spent $30,000 to check the school, but investigators found no environmental cause.
—Earlier in 2007, a mysterious illness swept through a Catholic boarding school in Chalco, Mexico, causing 600 girls to suffer fever, nausea and buckling knees that left many unable to walk. Batteries of tests found no physical cause.
—In 2002, 10 teenage girls at a small, rural North Carolina high school had epileptic-like seizures and fainting. The school buildings were inspected, but nothing was found to explain the outbreak.
Allegations of fakery sometimes surface, but most experts believe these patients have real symptoms that they can’t consciously control.
One thing they often have in common, is some kind of precipitating stress in their lives.
