The agent of Kawasaki disease, a potentially fatal illness in children, floats into Japan on seasonal winds from northeastern China, according to a report published today in the Proceedings of the National Academy of Sciences.
The pathogens responsible for the disease enter through mucous membranes and work their way into the arteries of young children. After the initial symptoms—including fever, rash, bloodshot eyes, and swollen hands and feet—subside, the disease leaves behind cardiac effects that can lead to heart disease and even death years later.(Related: "The Disease, My Friend, Is Blowing in the Wind.")
More than 40 years after KD was discovered, there is still no diagnostic test for the disease, and the pathogen that causes it—whether toxin, fungus, or other agent—remains a mystery.
But the discovery that the disease-causing agent travels on the wind "will lead us to the cause of Kawasaki disease," said study co-author Jane Burns, director of the Kawasaki Disease Research Program at the University of California, San Diego.
Kawasaki disease is the most common cause of acquired heart disease in children in developed countries. Japan, the country with the highest incidence of KD, reports more than 12,000 new cases each year. In the United States, some 5,000 to 6,000 cases are reported annually.
"We know that KD occurs on every continent and in every race," noted study co-author Daniel Cayan, a climate researcher at the Scripps Institution of Oceanography in La Jolla, California. This research presents a model that scientists can use to search for other regions harboring the Kawasaki agent, he said.
About ten years ago, after noticing a distinct seasonality in cases of KD, Burns, Cayan, and an international group of researchers began examining Japan's extensive database on the disease as well as wind patterns over that country. They traced outbreaks of KD in Japan to northeastern China, an area of intense agriculture.
KD was first described in the 1960s, around the time farming practices in that region, and around the world, were dramatically changing. "A more focused investigation should center in this area to precisely determine whether pesticides or fertilizers used have had a role in the generation of these particles," said the study's lead author, Xavier Rodó, a climate scientist at the Catalan Institute of Climate Sciences in Barcelona. There is "no doubt that agricultural practices do have an important implication in this story," he said.
What makes KD particularly sinister is that many of its early symptoms mimic those of other common childhood diseases. "Disease recognition is really a problem," said Burns. "Over the course of a week to several weeks, the fever subsides and the child feels better."
Treatment, which includes high doses of intravenous gamma globulin, an immunizing agent that boosts a patient's resistance to disease, can help reduce the risk of future health complications. But that treatment must begin early.
With this new research, Burns said, "we should be able to come up with an early warning system for pediatric emergency rooms, letting them know when they should have a heightened awareness for cases of KD."