According to research conducted at the Southern Illinois University, head lice have mutated to counter-act common over-the-counter medications. In reaction to a particular chemical used in common remedies against the pests, head lice have cultivated a resistance to permethrin. Scientists have found that head lice in 25 states have propagated with the genetic alteration.

Dr. Kyong Yoon, part of the study, said, “What we found was that 104 out of the 109 lice populations we tested had high levels of gene mutations, which have been linked to resistance to pyrethroids.” Pyrethroids are a breed of insecticides used to combat mosquitoes and other pests, which include permethrin, the most active chemical in over-the-counter head lice treatments.

Dr. Kyong Yoon has been studying the phenomenon since was a graduate student at the University of Massachusetts in 2000. But the first acknowledged analysis was discovered in Israel in the late 1990s.

The use of pyrethroids dates back to the late 1970’s when house flies developed a countermeasure as farmers began employing it in place of DDT. Dr. Yoon tested head lice for the same trio of genetic mutation known as KDR, or “knock down resistance.” He took a wide sampling from 30 states and found that 25 of them had the KDR resistance. States included in the canvass were California, Texas, Florida and Maine, and some head lice gathered had the KDR trio, making pyrethroids futile.

Populations that were taken from four states, New York, New Jersey, New Mexico and Oregon had one, two, or three mutations. However, the one state where the chemical was still effective was in Michigan. Studies are being administered as to why Michigan is the only state.

KDR mutations affect the insect’s nervous system and anesthetize them to pyrethroids. Yet head lice can still be managed with prescriptive medications. Dr. Yoon said, “If you use a chemical over and over, these little creatures will eventually develop resistance,” and added, “So we have to think before we use a treatment. The good news is head lice don’t carry disease. They’re more a nuisance than anything else.”

Source: Daily Mail