Selfies may promote the spread of head lice, experts warn.

"I've seen a huge increase of lice in teens this year," Marcy McQuillan of Nitless Noggins, a lice removal service, told SFist. "Typically it's younger children I treat, because they're at a higher risk for head-to-head contact. But now, teens are sticking their heads together every day to take cell phone pics."

McQuillan's theory is supported by Nancy Gordon, one of the founders of the National Association of Lice Treatment Professionals and CEO of Lice Knowing You.

Gordon says she has also noticed a significant increase in lice among older children in the last three to four years - something she admits has many parents baffled.

"I often say to them, 'Have you seen the way teenagers greet each other lately? Teenage girls can barely say hi to each other without hugging,'" she told The Huffington Post.

Gordon said she cannot confirm whether or not the selfie phenomenon is a direct cause behind the increase in lice in young adults, but admits it's a definite possibility.

Vanessa Mor of Oakland's Lice Control told CNET she's also seen an uptick in lice among teens and young adults. She did not directly blame the cultural phenomenon, but neither did she dismiss the idea completely, saying the theory makes a whole lot of sense.

"In order to get it, you have to be in direct contact - sitting on the same towel, sharing headphones together or using someone else's hair curler, sharing hats, sweaters, and scarves," she said.