When David 'Dush' Barashi walks up to you in the hallway, you're not entirely sure this guy is human. He comes across as animated, a cartoon figure come to life. You feel like you're meeting a Disney character. Perhaps from "Aladdin" or "Pirates of the Caribbean." His mop of salt and pepper hair and twistable mustache looks like it spawned from the barbershop of Tim Burton.

And then he speaks – English tinged with a mellifluous Mediterranean accent – and now you're certain this guy can't be real. He's wielding a baseball bat and a harmonica. He's got a pink handkerchief wrapped around his neck, a white shirt presumably purchased from a haberdashery for buccaneers and pants that look like they could double as a picnic tablecloth.

Once your mind settles in for the ride that is an encounter with Barashi, you finally focus in on his face. Between the bulging eyeballs and the wacky facial hair lies the answer to the enigma that is the man standing before you. A bulbous red nose protrudes from his face. David Barashi is a clown, but if you've learned anything in the minute-and-a-half since you entered his orbit, you know he's not your average party entertainer. After all, we're standing in a hospital.

It's a spring day in Jerusalem and Barashi and I are standing in the children's ward at Hadassah Medical Center, one of Israel's largest hospitals. He's making the rounds, as he's been doing for the past 16 years. Back when his hair wasn't so grey. But regardless of the passage of time, he remains a force of nature, a whirling dervish ping-ponging his way from room to room.

One moment, he's playing catch with a kid. The next, he's humorously helping distract a woman experiencing labor pains. Later, he's at the bedside of a senior citizen, bringing a smile to their face. He goes by the nickname "Dush".

Medical clowning has been around for decades, but came into the mainstream consciousness with the 1998 film "Patch Adams." The movie starred Robin Williams in the titular role, and was based on a real-life character, a doctor who now runs the Gesundheit! Institute in West Virginia. Studies have shown, like a recent one out of nearby Tel Aviv University, that clowns help kids suffer less pain during medical tests.

Israel takes particular pride in its medical clowning community. A group of about 80 volunteer clowns comprise the Dream Doctors, and are dispatched around the globe in the wake of natural disasters like the earthquakes in Nepal and Haiti, both places where Barashi himself went to work his charm. They've helped set up orphanages in Africa, and to the U.S. after devastating hurricanes. Another non-profit, called the Clownbulance, traverses the Mediterranean country fulfilling big-ticket dreams for sick children. It's like the Israeli version of the Make-A-Wish Foundation.

Clowning is taken to the next level at Hadassah, where the performers actually become an integral member of the medical team. During routine procedures – like when a child gets his blood drawn or is about to be sedated – you'll often find a doctor, a nurse and a clown in the room. The clowns will escort the patients into the surgery room.

"The clown can support the patient," Barashi tells me. "He is not just a joke or a funny guy that comes to the hospital."

For most children, being in a hospital can feel strange. "The first thing that I want is to take these kids out of the bed, to bring their childhood back, to give them the opportunity to choose to do what they want," says Barashi. "Because the doctor, the nurse and the others medical staff, they actually give them a lot of things that they need to do. But the clown comes and asks them, 'Would you like to be who you are, a child?'"

David Barashi has been working at the Israeli hospital for more than a decade. Here he is in 2013.

While the doctors prepare for a procedure, Barashi interacts with the children, trying to gauge their level of fear and emotional stress. "It's not home," Barashi explains to me. "The room is filled with other people that they don't know. So the clown can come during those moments and give the patient a way of how to look at it in a very positive sense."

Barashi and other Israeli clowns have become such experts in the field that they travel the world giving seminars in medical clowning. Shortly after my visit, Barashi was in Washington, D.C. for a workshop.

For Barashi, who is himself a father, working to bring joy to children in need can be difficult. "I will tell you something," Barashi reveals in between visits to patients' rooms. "The clown doesn't need to be happy every morning. When he wakes up, he's celebrating life every day. Sometimes I come to the hospital and I'm very low energy because things happen in your life, you know? But you find the power here."

He believes that it's sometimes the patients themselves who cheer him up. "This is the circle of giving," he says with a smile.

It's lunchtime and Barashi needs to continue his rounds. "I see every day the impact of what I'm doing," he tells me as I get up to leave. "In medical clowning, you don't need to wait until the end of the show to hear the applause. You don't need all the magic, and the light, and sound, and props, and everything. You just need your own silhouette, and a very nice object, and a small thing to create music, and a very positive dynamic and energy. And this is a show. It's the circus of life. It's not something that you write down before. You improvise with your partner. And your partner, sometimes he's a very sick patient. Sometimes he's a doctor or a nurse, but they are your partner – and they are part of the creation."