Jett Travolta and Kawasaki Syndrome

Actor John Travolta poses with his daughter Ella Bleu, left, wife Kelly Preston, right, and son Jett in a family photo.

The Internet is awash with rumors over the cause of the tragic death of actor John Travolta's 16-year-old son, Jett, who died January 2. I don't want to rehash the arguments over whether Travolta and his wife's belief in Scientology influenced the family's healthcare decisions. But amidst all the to-and-fro stands a startling bit of medical history: Jett, who had chronic health problems including seizures, had been seriously ill with Kawasaki syndrome as a toddler.

Something else for parents to worry about? Doctors who treat children with Kawasaki say it's highly unlikely that the mysterious ailment had anything to do with the teenager's death, because the heart damage typical of the disease happens soon after symptoms start. A 2007 Taiwanese study found that 43 percent of children who were diagnosed 10 days or more after the fever started suffered coronary artery problems, compared with 14 percent of children diagnosed earlier.

Kawasaki is the most common cause of noncongenital heart disease in children (although with more and more children having high cholesterol, that may soon be changing). With Kawasaki, coronary arteries get seriously inflamed, which can cause aneurysms, heart muscle damage, or sudden death. Children under age 1 are most at risk of having serious complications, according to this briefing from the American Heart Association. Prompt treatment with immunoglobulin and aspirin can lower the rates of cardiac problems from 25 percent to 5 percent. But to get treated, a child has to have been diagnosed. And the syndrome remains devilishly hard to spot.

Here's what to look for:

• Fever
• A rash or swelling of the hands and feet
• Whites of the eyes turning red
• Swollen lymph nodes in the neck
• Inflammation of the mouth, lips, and throat

That sounds a lot like the flu. In a 2003 New Yorker article, writer Cynthia Zarin describes her agonizing effort to get her 3-year-old daughter's mysterious illness diagnosed: "Looking down at my own child on the stretcher, I notice two things: The whites of her eyes are bright red, and the fingers on both hands look scorched, as if somewhere along the way she's burned herself."

Doctors still haven't been able to nail the cause of Kawasaki; viruses, bacteria, and genetic variations are all suspects. Since there's no clear way to prevent Kawasaki, the best defense is to call the pediatrician when the symptoms are puzzling or scary or if, like Zarin, your parental radar tells you there's something really wrong this time.