Scott Weiss had only recently opened the South Bay area’s first lice-treatment center, and already he had rid clients from 22 regional schools of the human-scalp parasites.

Students from Redondo Beach, Torrance, Palos Verdes,  Manhattan Beach, and Carson all were treated with a proven, 5 step process that Torrance Lice Removal employs to get kids lice free in about 1 hour — no harsh chemicals — to kill the hardy insect.

Lice infestation is widespread and growing, affecting 1 in 20 children ages 5 to 17 and nearly always spreading to their mothers and other family members.

Having adapted to popular over-the-counter products such as Nix Cream Rinse and RID Lice Killing Shampoo, lice are proliferating among middle and high school students — especially those who are social and take close-up group selfies.

A study published in March in the Journal of Medical Entomology found that traditional products are only 28 to 55 percent effective. New products like Ulesfia, Natroba and Sklice have been brought to market but the old treatments “continue to dominate the louse treatment market as inexpensive and easily obtainable,” according to the study.

Despite their prevalence, the discovery of a lice infestation is usually met with shock, confusion, tears and embarrassment.

“Most girls come in crying,” Weiss said. “When they leave, their sense of worth and confidence is better. They’ll do anything to make it go away.”

Weiss’ Torrance clinic is one of two he operates to kill lice and their eggs without harsh chemicals. Adults are easier to get rid of than the sticky, tough-shelled nits.

Eric Camara brought his 10-year-old daughter Katelyn to the Torrance clinic on Friday after the family spent two days trying to clear the bugs with over-the-counter treatments that were time-consuming and not very effective.

“It just came out of nowhere,” Camara said. “My wife woke up and showed me her hair. I saw the bug. I was just in shock. She started crying.”

Katelyn first noticed the bugs on her hairbrush: “I saw one and I was like ‘ewwww.’ ”

Her grandmother warned that lice are a bad omen.

Misinformation abounds about the bugs: that they’re caused by dirty hair and only affect poor people — both untrue, as lice prefer clean hair and don’t discriminate by age, race or class. They simply crawl to the nearest warm human scalp (they don’t infect animals).

The Camaras found the Torrance lice-treatment clinic online and showed up tired and emotional after trying to kill them with drugstore products and pick the eggs out individually.

“It’s embarrassing,” Eric Camara said. “I thought, ‘people will look at me like I’m a bad father.’ I never thought she’d get this.”

Weiss said the stigma is very common. Even when he calls schools to report that their students are having an outbreak, nurses routinely don’t believe him, he said. And families are likely to keep the information to themselves out of embarrassment.

“You can do all the cleaning you want, but, once they’re on your head, they won’t go away,” said Weiss, who also has an office in Los Alamitos. “They can infect anyone. Seal Beach and Los Alamitos are my biggest cities.”

He opened the Los Alamitos office last year, after his wife and three children suffered a lice infestation and struggled to find a product that would actually remove them once and for all.

“I watched my whole family cry and scream for three weeks,” he said. “We didn’t know the bugs had become resistant. My wife missed work and my kids missed school.”

They had to travel to San Diego for the treatment. So, shortly after their ordeal, they got into the lice-killing business, opening the Los Alamitos office last year and the Torrance clinic last month.

Each female lays six eggs a day for several weeks until she dies, allowing for exponential growth. But the treatment is comfortable, and Katelyn waited out the procedure playing Subway Surfers on her phone.

Head-to-head contact with an infected person is the main way lice are spread. Weiss advises using natural methods to kill live lice and their eggs.

“When people call me, it’s a stressful time in their life. The same questions are asked every time, and the number one thing they say is: ‘I went to CVS and got products and it still hasn’t gone away.’ ”

Torrance Lice Removal is at 2050 Artesia Blvd. #104 in Torrance.