World Autism Awareness Day draws attention to an illness that now affects 1 in every 88 children in the United States. The figure was cited in a study on autism spectrum disorder recently released by the CDC; the report also reveals that the disorder is almost five times more common among boys than girls. The largest increases were among Hispanic and African-American children.

The CDC report, published in the March 30 issue of Morbidity and Mortality Weekly ReportPrevalence of Autism Spectrum Disorders – Autism and Developmental Disabilities Monitoring Network, 14 Sites, United States, 2008, found a 78% increase in  cases of autism from 2002 to 2008.

Why the increase? One theory is that it’s due to increased awareness — thanks to events like today’s World Autism Awareness day — but health experts warn that this is not responsible for the entire trend.

According to the study, more children are being diagnosed by age 3, an increase from 12% for children born in 1994 to 18% for children born in 2000. However, 40% of the children still aren’t getting a diagnosis until after age 4.

Today, the global autism community celebrates World Autism Awareness Day, which encourages  measures to raise awareness about autism throughout society and to encourage early diagnosis and early intervention.