TOKYO -- Kawasaki disease, a childhood illness causing blood vessel inflammation throughout the body, is more likely when children are exposed to hot weather, a study by researchers in Japan has found.

Because of climate change, the number of days hitting 35 or 40 degrees Celsius is expected to increase, and the research team including Nobutoshi Nawa of the Department of Public Health at the Institute of Science Tokyo, commented, "Having children avoid high-temperature environments could help reduce the risks."

The cause of Kawasaki disease is unknown, and it affects mainly children from newborns to the age of 4. Symptoms include fever, redness in both eyes, reddened lips with bumps on the tongue, and rashes. In serious cases, it can cause coronary artery aneurysms and other lasting heart issues, increasing future heart attack risk.

The research team analyzed about 48,000 hospitalization records for Kawasaki disease nationwide during the warmer months of May through September from 2011 to 2022. It compared these records with Japan Meteorological Agency data to ascertain the relationship between the risk of hospitalization and the average daily temperature.

They found that when the average daily temperature was higher, the risk of hospitalization with Kawasaki disease increased. Specifically, exposure to extremely high daily mean temperatures in the top 1% -- corresponding to a temperature of 30.7 C or more -- was associated with a 33% higher risk of hospitalization within five days when compared to children in the lowest risk group with a mean temperature of 11.3 C.

Nawa, who is also a pediatrician, commented, "Early diagnosis and treatment are key in preventing Kawasaki disease's aftereffects. As extreme heat days are expected to increase with global warming, medical service workers need to prepare for the potential rise in patient numbers as temperatures rise."

The team's research results were published in the Oct. 30 edition of Dutch international environmental science journal Environmental Research (https://doi.org/10.1016/j.envres.2024.120231).

(Japanese original by Yoshimi Nakamura, Lifestyle, Science & Environment News Department)