According to a research presented at 250th National Meeting and Exposition of the American Chemical Society which took place in Boston, MA lice have started to resist commonly used treatments. This is the first study which has analyzed head lice from large US populations.
In case or head lice infestation people usually use over-the-counter medication that usually contains permethrin which is part of an insecticides family called pyrethroids. Such insecticides kill both lice and their eggs. Lice are spread through direct contact with the hair of a person which is infected with lice and such infestations are common among schoolchildren. Lice which are also known under the name of Pediculus humanus capitis live on the human scalp and feed with blood.
Receiving help from health workers the research team gathered head lice samples from 30 US states including Maine, California, Texas and Florida. The total number of samples came from 109 lice populations. Kyong Yoon of Southern Illinois University in Edwardsville explained that the number of head lice that are resistant to pyrethroid has increased over the last 20 years.
Actually Yoon discovered this for the first time in 2000 at the University of Massachusetts. Afterwards he tested lice samples from nearby schools looking for gene mutations that were also identified in the case of flies that grew resistant to pyrethroids. Yoon’s assumption proved to be true. Many of the lice showed all the three gene mutations which affect the nervous system of the parasites and make them less sensitive to the effect of pyrethroids.
Lice population from Oregon, New Mexico, New York and New Jersey had either one or two mutations. Michigan was the only state whose lice population was found to be susceptible to pyrethroids.
After this research the scientists discovered that 104 of the total number of 109 lice population in the study contained the same mutations (L920F, M815I and T917I). These mutations are known as kdr, standing for knock-down resistance. The lice population in the study was 100 percent resistant to pyrehroids.
The study indeed raises concerns regarding the effectiveness of the commonly-used lice treatments. However according to Yoon there are some prescribed lice treatments which contain insecticides that can destroy lice so people do not need to worry.
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