Lice turning into a serious problem as they evolve to become harder and harder to kill

Around the world, head lice have been a problem for as long as human beings have existed. The blood-eating parasites have frustrated parents of school-age children or anyone else who catches them for as long as history can remember.

"Head lice have been around as long as humans. They have been picked, preserved, from Peruvian mummies, and pried from the teeth of a Roman soldier’s comb," wrote Paula Cocozza in the Guardian. 

However, pesticide overuse and the process of genetic mutation mean that lice are becoming harder to kill. A whole industry has sprung into existence that offers a panoply of treatment methods and varying ideas about how to best rid patients of the stubborn pests.

Cocozza said that there are 6 to 12 million cases of head lice per year in the U.S. and that 8 to 10 percent of school-age children in the U.K. are believed to be infected at any given time.

First, she visited Isma Javid at her lice removal salon in London. Javid is opening a series of salon-style clinics throughout Great Britain known as Lice Clinics of the UK.

Javid's technique for lice removal involves a device called the AirAllé, which forces hot, dry air through the hair, which kills lice and dries up their sticky egg sacs, or "nits."

There are dozens of purported folk remedies for lice, ranging from oils, to vinegar to mayonnaise. In 2015, a Massachusetts toddler died when she aspirated mayonnaise that a relative had rubbed into her hair to kill a case of head lice.

"Some believe in electronic combs that beep upon execution, or use a vacuum to suck out the worst. Others apply heated straighteners, then stow bedding in the freezer to kill any off-head survivors. Some swear by dimethicone treatments. Others try them and curse," wrote Cocozza.

The British Community Hygiene Concern said that the sure-fire way to eliminate lice is to comb and comb the victim's hair -- a time-consuming process for even small families because every single strand must be combed.

To begin, wet the hair and apply a generous amount of conditioner, which renders the lice immobile and makes their eggs less sticky and therefore unable to adhere to the hair shaft. The comb must start at the root of the hair and comb the entire hair shaft to the end.

"Any gap between the teeth and the scalp at the start is an escape route for a louse," said Cocozza. "To comb a mid-length head of hair takes about an hour and a half (or that’s how long it takes me), and all family members should be combed on the same day to avoid cross-contamination. In my case, that’s about five hours of combing."

"In the US, there are hundreds of clinics that offer a one-stop comb-out, many of them launched by mums who found that their own tenacity was the most reliable solution," she said. "It’s a whole new cottage industry."

Researcher John Clark told Cocozza that he and his team found a few months ago that lice were evolving pesticide resistance. They published their findings in the Oxford University Journal of Medical Entomology.

"We’d seen it many times in agricultural insects,” Clark said.

Many products that were once highly effective are now obsolete. Nix, for example, which was once the industry standard, now only works 25 percent of the time.

New products like Sklice and Natroba are available only by prescription and, Clark said, “a lot of insurance companies won’t cover the cost."

And if you are scratching your head right now, you're not alone. Phantom itching from the mistaken belief that you have lice is called delusional parasitosis and is very common. Itching is also a sympathetic autonomic response triggered by "mirror neurons" in the brain. Talking about itching, thinking about it or, yes, reading about it can make you itch. So, scratch away.