You’ve noticed the symptoms: infectious smiles, contagious laughter, and boundless energy. Uh-oh. Looks like somebody has a case of the sillies.

The cause: Kapu Tickle Toy Camera, an iPad and iPhone app featuring 1950s-style illustrations that you interact with in all sorts of playful ways.

Swipe a string and people and animals change into entirely new creatures (ahoy, pirate monkey!). Take a picture of yourself and turn it into one of the on-screen characters. Or change the background on a whim to keep things fresh.

Of course, nothing beats tickling the characters and hearing them squeal as they spring up like jacks-in-the-box. Not since the invention of “coochicoo” have toddlers been so delighted.

Consider your cabin fever cured.

Available at itunes.apple.com, $1.

Photo: Courtesy of Kapu