Lice infestations in Australia
In a laboratory in the Faculty of Veterinary Science at the University of Melbourne, Vern Bowles slides a Petri dish into a microscope and centres it on two coffee-brown lice eggs: one is full and opaque, the other empty and almost entirely translucent. Suspended to their right, like a distorted astrological sign, is a big, fat louse. The microscope illuminates her segmented body, creepy-crawly legs, and the dried scraps of blood in her gut. Bowles is the chief scientific officer at Hatchtech, a biotech start-up developing a new kind of lousicide. When I ask him why lice are interesting, his face lights up. They are “fascinating,” he tells me. “Amazing!”
Most of Australia’s parents feel differently. Their indoctrination into the world of head lice is typically quick, brutal and itchy. When my son started primary school, I missed the telltale signs. Soon enough we were all clawing at our scalps. We doused our hair with a fluid that smelled like flea-shampoo and raked fine-toothed combs over flinching heads. The experience was repulsive, and yet lice treatments must be applied at least twice, so we did it again the following week. Still, every six months they returned. What drives most parents really insane is the louse’s absolute ineradicability.
Even after many bouts, we aren’t sure how to get rid of lice for good. Louse misinformation is as ubiquitous as lice themselves and, worse, many parents feel stigmatised by a lice infestation. Nevertheless, if you do talk about lice, the same themes recur: it wasn’t like this when we were kids; treatments are laborious and ineffective; synthetic products are toxic; natural products work only for the lucky or the righteous; and, weirdly, it is always the same child who catches lice. Underlying all of this is the notion that we can be truly lice-free.
Expecting that we can vanquish lice, let alone do it easily, may be our first mistake. The lice that plague Australia’s schoolyards today belong to a lineage that has tracked all of human history. Lice combs feature in Renaissance paintings of the baby Jesus. They were buried in the tombs of 3000-year-old Egyptian mummies (for the lice in the afterlife). Scientists even found a 10,000-year-old nit clinging tenaciously to a human hair in north-east Brazil. Genetic studies show that Pediculus capitis has followed our receding hairlines through millions of years of ape–human evolution, and now it is brilliantly adapted to the human head. I spoke to Steven Barker, a parasitologist at the University of Queensland, who has examined the parasite all over the world. He says, “We will never eradicate lice.”
Nevertheless, says Barker, for one brief moment in the twentieth century humans got the upper hand. Until the 1940s, lice in Anglo-Saxon populations were kept under control by the constant nit-picking of the family caretaker. Probably less than 5% of children carried infestations. After World War II powerful synthetic insecticides devastated many insect populations, including lice. Parents today who were born in the 1960s and early ’70s remember few lice in their childhood. Since then, lice have developed resistance to insecticides. They now infest up to 35% of 4–11 year old Australian schoolchildren once per year. Indeed, says Barker, “Australia may be the lice capital of the world.”
Although lice have been on the increase since the ’70s, it’s taken governments and markets a while to respond. Even today lice treatments are not tightly regulated and, until ten years ago, there were few controlled trials on their efficacy. As lice spread and more lice products began to jostle for space on the pharmacy shelf, companies started to supply peer-reviewed papers proving their products can actually cure infestations. Or, rather, most studies show a product can eliminate most of the lice most of the time – and possibly more than a competitive product. But if a single pregnant louse or just two eggs remain, the cycle will begin again. To help, Bowles points out, many treatments today are sold with a lice comb. “The question is, is it the product or the comb that’s removing the lice?” (In fact, Bowles says, physically removing lice is currently the only foolproof method for getting them out.)
Most treatments are neurotoxins. They damage the nervous system of the louse but they generally don’t hurt the egg so treatment must be repeated in a week when remaining nits have hatched. Even if a neurotoxin can get inside the egg, it won’t do much until the third or fourth day when the nervous system has developed. Hatchtech, which is planning to enter a new phase of trials on children, has created a louciside and ovicide. When it’s time for treated eggs to hatch, enzymes involved in hatching are blocked, and the louse dies inside the egg.
If Bowles’s solution works, parents can use it just once, and Hatchtech may become more beloved than The Wiggles. But why has it been so hard to develop an effective product? In addition to resistance, safety and re-infestation issues, collecting and testing lice can be a challenge. Bowles tried harvesting lice from a school eradication program but says it was “feast or famine”. Stephen Barker’s university laboratory houses a colony of lice on which they regularly test commercial products. He tried cultivating test lice on his leg and his arm but they made him feel lousy. “That’s where the word comes from,” he said. “Lice inject chemicals into blood that make people feel bad, they disrupt sleep and may also make thinking fuzzy – which is why people used to call the afflicted ‘nitwits’.”
It’s not just insecticides that have given up killing lice. Many parents have, too. Eliminating them is time-consuming, it can be traumatic for children, and even if you achieve it, another parent may not. “It’s going to take a couple of generations to lower lice levels again,” says Barker. In the meantime, he adds, “Bowles is right, we need new classes of treatments for eggs.” There may be some comfort in the idea that resistance could cut both ways. Consider the tribe on remote Satawal Island in Micronesia where almost everyone has lice, and elaborate grooming rituals surround their removal. In that group, the socially challenged are the ten or so people who never seem to catch lice no matter how many times they put them on their heads. Closer to home, biologist Deon Canyon at James Cook University tried to cultivate a lice colony on his head but could not get them to take. He found that up to 15% of the lice that drank his blood haemorrhaged to death. It’s not what you’d call justice but it scratches an itch.