Lice: What Every Parent Needs to Know
Lice are tiny insects that live on humans and feed on blood. Lice lay (eggs) nits – which are often mistaken for dandruff – and hatch in 8-9 days. These young lice (nymphs) look like tiny lice and mature in 9-12 days. Adults are the size of a sesame seed and are usually white, though they can be brown or black. Adults live up to 30 days and lay about 6 eggs per day.
How Do You Get Lice?
Lice typically appear on the scalp of young children, but can quickly spread throughout a family. Up to 12 million children in the US are infected with lice each year, but those numbers are not equally distributed. Children ages 3-11 are the most likely to be affected; girls more often than boys.
Because lice feed on blood several times each day and crawl rather than fly or hop, they are typically found close to the scalp, at the bottom of the neck, behind the ears, or near the center of the scalp. This feature also means that close contact with an infected individual is required for contamination. They won’t hop from person to person; they need some form of close contact to reach a new head. This need for blood multiple times a day also means that they will die in 1-2 days if they fall off a head, so shared hairbrushes, pillowcases, and hats can spread lice if they are exchanged frequently.
This time delay is also important when considering how to treat items that have been exposed. Lice are not a sign of poor hygiene; washing sheets and hats won’t eliminate them because they can live underwater for several hours. And as frustrating as a lice infestation can be, they are more of a social concern, and source of mild discomfort rather than a health concern. They do not spread disease.
How Can I Prevent Lice?
The most effective method of prevention is physical. Avoid infected individuals, as well as potentially contaminated items. Avoid head to head contact. Don’t share brushes or hats.
If you have a known exposure, machine wash clothing and linens with 130 degree water and a high heat drying cycle. Alternatively, place items in a sealed plastic bag for two weeks to ensure all live lice are gone. Vacuum frequently for any lice that may have fallen off of an infested head. Focus on their two day window of survival, allowing a few extra days for the longest lasting survivors.
Another thing to consider: many schools have a no-nit policy, but this approach is not supported by scientific research. If no live nits or adults are seen, and the only nits are away from the scalp, the child is free of lice. Remember, they need access to blood to survive.
What Can I Do About Lice?
Due to the social constraints of a lice infestation, it’s tempting to jump into action over a single louse in a child’s head, or even to the news of an outbreak at school. It’s important to resist that urge because it leads to unnecessary pesticide use on a child’s head. Not only does this pose an unnecessary risk for the child, it encourages the development of treatment-resistant lice. Many commercial lice treatments are now only 25-30% effective as a result of this overuse.
Not only are commercial lice treatments overused; they are often misused. These products only kill adults, so they should be reused every 30 days until the infestation is fully resolved. Many parents apply it only once thinking the condition has been treated, only to see it reemerge six weeks later.
What About Natural Alternatives?
TEA TREE ESSENTIAL OIL
While many people turn to tea tree oil as a standby for lice treatment and prevention, it is not necessarily the most effective approach on its own. For example, in one study, tea tree oil was found to inhibit fewer than 60% of eggs in a controlled environment, as compared to cinnamon bark, which inhibited 100%. For best results, blend the oil with other essential oils.
EUCALYPTUS ESSENTIAL OIL
The most effective essential oil for lice infestations is eucalyptus (E. globolus). In one study of 152 participants, this topical shampoo and leave-in application was found to get rid of 82.5% of the infections, whereas those who used conventional treatments saw elimination rates of 36% and 29%.
ESSENTIAL OIL BLENDS
In in vitro studies (studies outside of a living organism) essential oils which were found to be the most effective include: cinnamon leaf, eucalyptus, rosemary, sage, peppermint, clove bud, clove leaf, and coriander.
Using Essential Oils to Prevent or Treat Lice Infestations
Use physical barriers and avoidance for prevention, especially avoiding close head-to-head contact, hats, brushes, and shower caps. In the case of exposure, use appropriately formulated preventive sprays and shampoos 1-2 times daily for 3-4 days. For aggressive treatment, use a more powerful leave-on oil blend in coconut oil every week for 4-5 weeks.
REFERENCES
Ariel C Toloza, Alejandro Lucía, Eduardo Zerba, Hector Masuh, and María Inés Picollo. (2010). Eucalyptus essential oil toxicity against permethrin-resistant Pediculus humanus capitis (Phthiraptera: Pediculidae). Parasitology Research 106(2):409
Han-Young Choi, Young-Cheol Yang, Si Hyeock Lee, J Marshall Clark, and Young-Joon Ahn. (2010). Efficacy of spray formulations containing binary mixtures of clove and eucalyptus oils against susceptible and pyrethroid/ malathion-resistant head lice (Anoplura: Pediculidae). Journal of Medical Entomology 47(3):387.
Doaa A Yones, Hanaa Y Bakir, and Soad A L Bayoumi. (2016).Chemical composition and efficacy of some selected plant oils against Pediculus humanus capitis in vitro.
Parasitology Research 115(8):3209.
Kerryn A Greive and Tanya M Barnes. (2002). In vitro comparison of four treatments which discourage infestation by head lice. Parasitology Research 110(5):1695.