Resistant head lice don't respond to standard treatment and need other methods for effective eradication. Beause lice spread quickly in school and daycare environments, infestations are difficult to stop and resistance makes it even more difficult. According to the pediatric health website DrGreene.com, about 12 million people get lice each year in the U.S. and resistance to the common drugs used against lice is increasing.
Description
Head lice live on the scalp, often infecting children. While head lice don't cause any major complications, they can be annoying and difficult to eradicate. Unlike many other insects, lice do not carry any infectious diseases. Resistance develops when a specific treatment for an organism is overused and the creature evolves over time so that the remedy is no longer effective. Other organisms that have developed resistance to standard drugs include bacteria resistant to common antibiotics and HIV strains that are resistant to standard antiviral drugs.
Standard Treatment
Because resistant head lice don't exhibit any physical difference that makes them recognizable, someone with a head lice infestation should first try using the standard remedies. Over-the-counter and prescription shampoos or lotions can be used on the head to attempt to destroy the lice. Some patients may experience mild itching or redness when using standard head lice medication. Persistence of lice two weeks after treatment may indicate resistance.
Treatment for Resistant Lice
In general, head lice are resistant to one drug or ingredient at a time, so trying a different drug is the first method of treating resistant head lice. A 2006 study in the Journal of Medical Entomology found that lice resistant to the active ingredient permethrin were still responsive to another drug, spinosad. Another method, suggested in a 2005 article in American Family Physician, involves coating the head in a solution that solidifies when dry, effectively suffocating the lice. This treatment is called dry-on, suffocation-based pediculicide, or DSP, treatment.
Alternative Treatments
Some people attempt to try alternative methods of lice treatment. Suffocation of the lice by covering the head with olive oil, mayonnaise, petroleum jelly or other thick substances is one method used, although there have been few studies on this method, so its effectiveness remains undetermined. Another natural method of lice treatment described by DrGreene.com is to blow dry the hair twice daily on high heat and immediately remove lice nits with a fine comb after heating.
Considerations
Sometimes, a treatment is ineffective but resistance is not the cause. If the directions are not followed exactly, some lice may survive the treatment and continue the infestation. Most treatments require refraining from washing the hair for one to two days after use. Not waiting long enough between hair washings is a common mistake, explains the website Kids Health. Because lice medications can be toxic, especially for young children, parents should avoid applying more than directed or using more than one product at a time. Overuse may also lead to the development of resistance.
References
- Centers for Disease Control and Prevention: Lice: Head Lice: Treatment FAQs
- KidsHealth: Are Head Lice Becoming Resistant to Medication?
- Journal of Medical Entomology: "Permethrin-resistant Head Lice (Anoplura: Pediculidae) in Argentina are Susceptible to Spinosad"; Mougabure Cueto G, Zerba EN, Picollo MI; May 2006
- American Family Physician: "Treating Resistant Head Lice"; Caroline Wellberry, M.D.; June 2005
- DrGreene.com: Treating Head Lice
