WASHINGTON (AFP) - The cause of the mysterious childhood disease, Kawasaki syndrome, could be an airborne toxin that is blown into Japan from northeast China and may be linked to farming, researchers said Monday.
Kawasaki disease causes fever, rash, peeling fingernails and in about 25 per cent of cases it can also lead to coronary aneurysm, a life-threatening ballooning of arteries that supply the heart.
While its cause has eluded researchers ever since the disease was first identified in 1967, scientists noticed it tended to affect children in Japan at certain times of the year.
"There are certainly other source regions around the globe, but focusing on the link between northeastern China, Japan, Hawaii, and the west coast of North America is our best bet for figuring this out," said lead author Jane Burns, professor and director of the Kawasaki Disease Research Centre at the University of California, San Diego School of Medicine.
Previous research using modeled air currents found that Kawasaki disease cases peaked only when winds originated from a vast cereal-farming region in northeastern China.
Scientists decided to test the air two to three kilometers over Japan, using an airplane carrying large-volume air-filtering equipment.
They found that the dominant airborne fungus was Candida, a member of the yeast family and the most common cause of a wide range of human fungal infections worldwide.
In research mice, Candida has been linked to a coronary artery syndrome that resembles Kawasaki disease.
The latest analysis in the Proceedings of the National Academy of Sciences says the most likely cause is a "pre-formed toxin or environmental molecule" originating from northeastern China and that may be related to Candida.
Their theory is that some sort of pathogenic airborne toxin or molecule appears to be picked up by the winds over areas where farming of grains is common.
When it reaches children who are genetically susceptible, it can cause unusual immune reactions.
Burns believes something must have changed in recent decades in northeastern China.
"Could they be burning a biomass fuel in winter that carries the agent on aerosolised ash to Japan? Could there be some agricultural practice or crop or activity that is new since the 1960s when KD first started to appear in Japan? Could it be that the aerosolized particle is chemically altered to become pathogenic as it travels through clouds on its way to Japan?
"We need to figure out what the activity or condition is that creates these aerosols carried by the winds," she added.
There is no way for doctors to prevent children from getting Kawasaki disease, though it is not contagious and most children recover fully within a matter of weeks.
First described in 1967 by its discoverer, Tomisaku Kawasaki, the disease is becoming more common among children in Asia, particularly in India and the Philippines, as well as the United States and Western Europe, researchers say.