Researcher: Kawasaki Disease Spike In San Diego Likely Tied To Aerosol Particles
An unusual and potentially deadly disease is making a growing number of San Diego County children sick, and researchers say it's caused by something in the air.
When 3-year-old Amelia Hurvitz was admitted to Rady Children’s Hospital in February, the toddler, with curly blond hair, had a high fever, swollen lymph nodes in her neck and red, cracked lips.
“She started having the rash, she started having red hands and feet that were swelling a little bit, and then her eyes were getting very bloodshot,” said Amelia’s mom, Laura Hurvitz.
Doctors immediately ruled out the flu, staph infection and mono, Hurvitz recalled.
“And as her symptoms kept … becoming more prevalent,” Hurvitz said, “that’s when they took her in for the echocardiogram and she was identified as Kawasaki disease.”
It was their worst fear, she said.
“Because the doctor had explained that it could impact her heart,” she said. “But luckily her first echocardiogram was clear.”
Kawasaki cases spike in San Diego
Amelia is among 50 children in San Diego County to be diagnosed with Kawasaki disease since January — that’s three times more than usual. The disease, often diagnosed in clusters, is characterized by inflammation of blood vessels throughout the body. It can fatally damage the heart of one in four children if it’s not treated early on.
“Kawasaki disease to me is the most compelling mystery in clinical pediatrics right now because the answer seems that it must be staring us in the face,” said Jane Burns, M.D., professor of pediatrics at UC San Diego and director of the Kawasaki Disease Research Center.
Burns’ team includes doctors, climate scientists, molecular biologists and geneticists with UC San Diego, Rady Children's Hospital and Scripps Institution of Oceanography.
She said most of the children recently diagnosed in San Diego County were treated early enough to prevent heart damage. A symptom of late diagnoses often includes peeling skin on the fingertips.
“Fortunately our emergency physicians and the general pediatricians in the community have really stepped up to the plate to recognize and refer these children in early,” she said.
But for some of the children diagnosed this year, early treatment wasn’t enough.
“We still had children who had early signs of damage to the coronary arteries,” Burns said. “Without the proper follow up, which can keep all of these individuals safe, there can be disastrous consequences.”
Researcher Hones In On Aerosol Particles From Asia
Burns and her team meet every week to discuss new research and review cases, including Jennifer Burney, PhD, an environmental scientist with UC San Diego.
Burney believes the culprit may be in the air flowing across the Pacific Ocean from Asia to San Diego, stirred up by unusual weather systems and storms.
“What we know is historically in San Diego County when you see these high incidents of Kawasaki, they’re associated with a set of conditions,” Burney explained. “Higher daytime and nighttime temperatures and reduced circulation across the Pacific.”
Burney said pockets of air seemed to get trapped, leading to a spike in Kawasaki cases.
“These sort of trapping conditions are when you have a much more still atmosphere,” she said. “Then, when we see that dissipate, then we see lower rates of Kawasaki — that’s associated with stronger, more regular air flow in the region.”
The unknown, she said, is what exactly is in the air that triggers the disease, first discovered after World War II. Burney’s research points to aerosols that fill the air with floating dust particles and droplets from natural resources, as well as man-made pollution.
“Some of these come from natural sources like dust or sea salt,” she said. “Some of them are biologic, like fungus, bacteria, virus, and some of them are from anthropogenic activity — burning fossil fuels, or transportation emissions, or burning biomass in particular puts a lot of aerosols up into the atmosphere.”
By studying data of when and where kids are getting sick, Burney is working to catch the culprit.
“We need to figure out, sort of statistically, how to sample for something that’s kind of sparse, potentially, in the atmosphere,” she said. “How do you do that in a way that you might actually catch the thing at the moment that it is exposing kids?”
Equally important is documenting conditions when there are no incidents of the disease, she said, such as during Santa Ana wind events that cause offshore breezes.
Japan has the highest incidence of the disease, but cases are found all over the world. Southern California is considered a “hotspot,” Burns said, with the rate of cases in San Diego doubling in the last 15 years.
Kawasaki cases appear in clusters
Kawasaki disease cases are usually discovered in clusters, connected in time and location, Burns said.
“In March we had a very tight cluster in the Chula Vista region,” Burns said. “In general the disease seems to have moved up into the Temecula, Hemet, Vista area — so inland and slightly north.”
She said patients within a cluster seem to be a lot like each other.
“So for example we’ll have clusters of very young babies and we have to think that they’re being exposed to something that must be very common in the environment because they didn’t get very far in their life before they came across it,” she said. “Then we’ll have other clusters that seem to favor much older children.”
Children who get Kawasaki disease have an underlying genetic susceptibility, Burns said.
“The current paradigm is that if you were born with the genetic susceptibility, you will get Kawasaki disease,” she warned. “It’s just a question of when you’ll come across the trigger.”
Burns, who dedicated her life to studying the disease after one of her patients died of it 35 years ago, said children of all races have been sickened, but Asian children and boys are at a higher risk.
“We would make such a difference in the lives of so many children throughout the world if we could find the answer to this” she said.
She imagines a time in the near future when every baby will be genetically screened for the disease.
“And then we would vaccinate them so they would never need to suffer Kawasaki disease, and we would just wipe it out,” she said. “That’s my dream. That’s a better world.”