They are the pet peeve of parents. On each return, mother and father must follow the same ritual: armed with a comb, they inspect, strand by strand, their child’s scalp in search of terrible creatures: nits and lice. These tiny insects measuring 2 to 4 millimeters and feeding exclusively on human blood are not dangerous and do not transmit any disease. But they cause itching and their transmission by direct contact is very rapid.
While there are plenty of chemical insecticides, sprays, shampoos, lotions, and oils aimed at eradicating these little critters, they are becoming increasingly resistant to treatment. But don’t panic, there are solutions.
A genetic mutation making them resistant
Marketed from the 1960s, pediculicides, products aimed at destroying lice, first proved to be very effective against them. But, tough, these parasites eventually developed resistance to pyrethroids, chemicals used in many anti-lice treatments. Genetic resistance. “We killed all the lice that were sensitive to these products, explains Arezki Izri, biologist and lecturer emeritus at Paris Nord University. The lice then had a mutation in a gene making the product ineffective. Today, the remaining lice are resistant lice.
But don’t worry. These resistances only concern chemical insecticides, less used in recent years. All the less to spread on the heads of toddlers as they give rise to “heaps of side effects”, according to André Paugam, doctor in the parasitology, mycology and tropical medicine department at Cochin hospital and lecturer at the University of Paris Cité. “Organophosphates can cause irritation, digestive disorders, asthma attacks, and even neurological disorders in some children. »
More or less effective solutions
To avoid these side effects and circumvent resistance to chemical insecticides, André Paugam advises using certain oil-based products, such as Dimeticone. This lotion, from the silicone family, works on both adult lice and nits. According to Arezki Izri, these oils are 100% effective in the laboratory, but lose 10-30% effectiveness when poured on children’s heads. Because in the laboratory, the louse is completely immersed in oil. The latter enters its respiratory system killing the parasite by asphyxiation. Not being able to completely drown the lice on children’s heads as is done in the laboratory, the oil is in fact a little less effective when used at home.
There are also some essential oils, less effective, of the order of 70 to 80% efficiency in the laboratory, according to Arezki Izri, and therefore even less in practice. If the parents have really tried everything and go, desperate, to Arezki Izri’s office, the biologist reminds us that he can prescribe Ivermectin for them. An antiparasitic tablet originally prescribed to fight against certain tropical worms and against the scabies mite but which gives good results in eradicating lice.
Since lice repellents are rather ineffective, the doctor at Cochin Hospital believes that “when a class is reached, all children should be treated at the same time”. The best prevention remains to comb your children regularly with a lice comb to check that they have not invaded their hair. Because, we remember, half of infected children have no symptoms.