The face of Avonte Oquendo, a 14-year-old boy with autism, has become very familiar to millions of New Yorkers. But despite the fact that his picture is plastered throughout subways and on street corners, he has proven very difficult to find. And unfortunately, that's a pattern shared in other cases involving missing autistic children, the number of which have risen dramatically in recent years.

Avonte has been missing for almost two weeks since he reportedly ran out of his school in Queens, New York. Some have wondered why his case has garnered so much attention when a child goes missing every 40 seconds in America.

The reason is that Avonte cannot verbally communicate, making the task of finding him exponentially harder than tracking down a typical missing adolescent. It also significantly increases the chances of death.

The ways in which Avonte and other children with autism interact with people are very different. "These children are unlikely to respond to their name," says Stephanie Millman of the Autism Science Foundation. "If you call their name and they don't respond, that doesn't mean they're not the kid you're looking for."

Another pattern is that these children with autism tend to burrow and "seek out small enclosed places, which may be overlooked during initial searches," says the National Center for Missing & Exploited Children (NCMEC). For example, when 8-year-old Robert Wood Jr. ran off while visiting a Civil War Park in Virginia with his father, he was ultimately found balled up in the fetal position in a quarry nook about a mile away. Luckily, even after six days on his own, he was still alive.

Avonte and Robert are just two cases that are part of a spike in missing children with severe autism, reports the NCMEC. As many as six children with autism go missing each week, and this year alone, 14 children with autism have wandered away and died. The Interactive Autism Network found that 49 percent of children bolt or "elope" after the age of four.

What makes these elopements all the more dangerous is that people on the spectrum are likely to put themselves in a harmful situation without realizing it, which is why "they are more likely to die than unaffected children," writes Russell Goldman at ABC.

Children on the spectrum often have a "diminished sense of fear," Robert G. Lowery Jr. of the NCMEC tells ABC. Because they do not register the high risks, they may walk straight into traffic or wander deep into a woods. Or, far too often, they go towards a body of water. In fact, 91 percent of missing children with autism who die do so as a result of drowning.

However, although all of these circumstances make finding a child with autism so difficult, volunteers have managed to employ innovative techniques. For example, a van from Citywide Disaster Services has toured Avonte's Queens neighborhood while playing a recording of his mother saying, "Hi Avonte, it's Mom. Come to the flashing lights, Avonte."

Although Avonte cannot communicate, there's hope that he will be able to follow the familiar sounds of his mother's voice. "We're hoping he hears it and is not afraid of the lights and will hopefully walk towards them," Keith Brooks, the program's director tells Fox.

Similarly, when an 8-year-old on the autism spectrum went missing in California in 2011, the sheriff's deputies played Ozzy Osbourne music in the search area because he loved the sound. It worked, and the music drew him out from hiding.

Autism advocates are also pushing for a version of Silver Alert for people with autism. The Silver Alert is currently used in various states to notify people via texts, radio, TV, and motor signs when people with Alzheimer's have gone missing. Some states are also beginning to enact Silver Alerts for people with autism. Unlike the Amber Alert, it is "localized and really tailored to the needs of the people who have gone missing," says Millman.

New York does not have an alert for people with autism, but hopefully the case of Avonte Oquendo will show how much it is needed.

If you have any information regarding Avonte Oquendo, please call NYPD officials at (800) 577-8477.