If you've been experiencing an itchy head just lately, it might be because you've been taking part in a group Selfie.
A expert says the phenomenon of putting our heads together to crowd into a mobile phone shot is causing an increase in the spread of nits – especially amongst teenagers.
Head lice specialist Mary McQuillan, from California, said: "I've seen a huge increase of lice in teens this year.
"Typically it's younger children I treat, because they're at higher risk for head-to-head contact.
"But now, teens are sticking their heads together every day to take... pictures."
But not everyone agreed with this theory.
Dr Richard J Pollack, from the Harvard School of Public Health said: "This is a marketing ploy, pure and simple."
Still, I bet you're scratching your head right now, aren't you?
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