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STEM

Of Lice and Men

Head louse on human hair

Head louse on human hair

Seems like it was just last week that media outlets reported that the U.S. was experiences a 50-state bed bug infestation. Now this week, at the annual meeting of the American Chemical Society (ACS) in Boston, MA, researchers reported that the lice population in 25 states has developed resistance to over-the-counter treatments.

I can’t figure out if eke or yuk is my desired reaction!

Head lice are parasites that are found on human heads. Unless you have children, thoughts of head lice have probably not entered your thoughts in a while. The word lice is plural for louse. The good news is that lice are not known to be disease carrying organisms.

According to the Centers for Disease Control (CDC), lice affects a greater number of elementary school students in North America than all other communicable diseases combined. An estimated 6 to 12 million infestations occur each year among children 3 to 11 years of age. Lice are spread by direct contact between people. [Ref 1]

Most schools offer educational materials on how to detect head lice, and what to do if you think your child may have them. Information is also available at public health departments as well as your doctor’s office.

“We are the first group to collect lice samples from a large number of populations across the U.S.,” says Kyong Yoon, Ph.D, one of the researchers presenting the data at the ACS meeting. “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.”

Yoon, who is with Southern Illinois University, Edwardsville, explains that the momentum toward widespread pyrethroid-resistant lice has been building for years. The first report on this development came from Israel in the late 1990s. Yoon became one of the first to report the phenomenon in the U.S. in 2000 when he was a graduate student at the University of Massachusetts, Amherst. [Ref 2]

This mirrors some of the strands of bacteria that have shown resistance to penicillin and other antibiotics from decades of use, and perhaps over prescribed as treatment for many ailments.

Many head lice medicines are available at your local drugstore. My primary interest in sharing this post was to provide a list of OTC products. Each OTCproduct usually contains one of the following active ingredients [Ref 3]:

  1. Pyrethrins (often combined with piperonyl butoxide, in brand name products: A-200, Pronto, R&C, RID, Triple X): Pyrethrins are natural extracts from the chrysanthemum flower. Though safe and effective, pyrethrins only kill crawling lice, not unhatched nits. A second treatment is recommended in seven to 10 days to kill any newly hatched lice. Treatment failures are common.
  2. Permethrins (NIX): Permethrins are similar to natural pyrethrins. Permethrins are safe and effective and may continue to kill newly hatched eggs for several days after treatment. A second treatment may be needed in seven to 10 days to kill any newly hatched lice. Treatment failures are common.
  3. Dimethicones (silicone oils, Hedrin, NYDA) coat surfaces and act as a physical barrier asphyxiating the louse and have been shown to be variably effective in studies depending upon the formulation.
  4. Lindane shampoo (formally known as Kwell) is a prescription drug and is one of the most common treatments for head lice. When used as directed, the drug is probably safe. Overuse, misuse, or accidentally swallowing Lindane can be toxic to the brain and nervous system, and because of this, only a single application is recommended.
  5. Malathion (Ovide) is another prescription drug that has recently been recommended as a first-line agent for the treatment of head lice. It is a combination drug and is mixed with isopropyl alcohol (rubbing alcohol) and terpineol (a naturally occurring tea tree oil extract), both of which have been shown to have some ability to kill lice. When used as directed, it is considered safe and has been available over the counter for many years in other countries such as the United Kingdom.
  6. Ivermectin (oral medication) has been used to treat helminthic infestations (worms) for many years. A March 2010New England Journal of Medicineresearch article compared the use of ivermectin vs. malathion for “difficult-to-treat head lice” and found that a treatment with oral ivermectin resulted in a 7%-10% higher eradication rate over topical malathion. There is evidence that in resistant head lice infestations, oral ivermectin may be better than malathion. (Oral ivermectin is not currently licensed for treating head lice.)

As a first line of defense, become educated on the problem, and follow instructions for eradication and treatment.

Sources Cited:

1.    Heading Back To School? So Are Drug-Resistant Lice, by Judy Stone, August 19, 2015, in Forbes Business, http://www.forbes.com/sites/judystone/2015/08/19/heading-back-to-school-so-are-drug-resistant-lice/?utm_source=Sailthru&utm_medium=email&utm_campaign=Daily%20Digest%20Send%20Test%202015-08-19&utm_term=Daily%20Digest%20Horizon

2.    ACS News Release: Lice in at least 25 states show resistance to common treatments, August 18, 2015, http://www.acs.org/content/acs/en/pressroom/newsreleases/2015/august/lice.html

3.    Head Lice: How Can I Prevent?, http://www.medicinenet.com/head_lice/page11.htm

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About Vi Brown

Vi is principal and CEO of Prophecy Consulting Group, LLC, an Arizona firm that provides business and engineering services to private and public clients. Prior to establishing her consulting practice in 2001, Vi worked with Motorola, Maricopa County Government, Pacific Gas & Electric, CH2M Hill, and Procter & Gamble. As an adjunct faculty member, Vi teaches undergraduate calculus classes and graduate level environmental courses. She is also a professional speaker.

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