Head lice: Misinformation, resistance in the pediatrician’s office
Summer is nearly upon us, and for many children in the United States, the season is about enjoying sun, sand, summer camp and sleepovers. However, many pediatricians will be spending the summer helping patients and their families deal with an unwanted guest: Pediculus humanus capitis, or the head louse.
Considered one of the oldest parasites, head lice are known to predate modern Homo sapiens by about 1.18 million years. Unable to fly or jump, head lice are neither ambulant nor particularly hardy parasites, dying within 1 or 2 days once removed from the scalp; they are, however, uniquely adapted to anchor themselves to hair shafts on the human head. Additionally, as a species-specific parasite, head lice cannot be spread through contact with animals, leaving humans as their sole source of food as well as their only means of transportation and dissemination to new hosts.
“Head lice have been with humans for thousands of years,” said Joseph A. Bocchini Jr., MD, FAAP, a professor and chairman of pediatrics at Louisiana State University Health — Shreveport. “They are well adapted to humans and, in fact, their entire life cycle is completed on the scalp. It is a well-developed relationship for the head louse.”
Despite their largely immobile lifestyle, head lice are reported to be responsible for an estimated 6 million to 12 million infestations each year in the U.S. among children aged 3 to 11 years; this age demographic is also most likely to gather in settings where summer activities with the direct head-to-head contact that head lice need to thrive are likely to occur, such as playgrouds, summer camps and slumber parties.
For many years, infestations have been easily and safely treated at home, without the help of the physician. However, with the rise in resistance to the over-the-counter (OTC) treatments, pediatricians are playing a more important role in diagnosing and eradication these pests. In this issue, Infectious Diseases in Children spoke with experts regarding the misconceptions many parents have about head lice, the current head lice policies in place for schools, summer camps and the daycare setting, and the optimal treatment methods in light of increasing resistance to OTC agents.
Confronting head lice myths, misconceptions
Although a common issue among children, and not associated with any disease risk, head lice infestations nevertheless can induce panic among parents of schoolchildren. Laboring under the age-old stigma that lice infestations are linked to poor domestic cleanliness and personal hygiene, parent and school communities have been known to enact disproportionate quarantine measures to contain head lice ‘outbreaks.’
Among the widespread myths about head lice, their association with poor hygiene has been the most difficult to debunk, according to Ashley A. DeHudy, MD, MPH, from the University of Michigan’s Mott Children’s Hospital. “It is important for families to know that this is a very common diagnosis that many people deal with. Anyone is at risk for lice infestation, since according to the CDC, personal hygiene and environmental cleanliness do not play a role in lice.”
In a study published in the International Journal of Dermatology, Parison and colleagues determined that the societal impact of head lice countermeasures, including quarantine and overtreatment, may have a more damaging effect on parents and children than the actual head lice infestation itself. Compared with perceptions of head lice in traditional societies, researchers found that parent populations in the U.S., Canada and Australia exhibited overwhelmingly negative emotions regarding head lice, further contributing to persistent head lice stigma.
While affirming that head lice infestation is common, regardless of socioeconomic status or living conditions, pediatricians are often forced to confront the misconception that head lice spread diseases. Unlike their larger cousins — the body louse, known to carry diseases such as typhus and trench fever — head lice are not a disease vector, although excessive scratching can occasionally increase the risk of a secondary skin infections.
“Head lice do not carry disease, as [they are] different than the body louse,” Bocchini said. “Head lice do not transmit any known infection.”
Additionally, pediatricians are encouraged to spend time educating parents about lice transmission, namely that people become infested with head lice, but inanimate objects or homes do not. Sleeping in a bed formerly used by a person with head lice, for example, is unlikely to spread head lice; however, sharing a bed or spending extended periods of time with heads close together – such as at a sleepover – represents significant risk factors for transmission, providing lice with sufficient time to crawl from one head to the other.
“Head lice often become a problem when people are concentrated together in one place, so naturally we think about children in the classroom, yet even more so during activities like summer camps; whenever people are head-to-head, that is when there is the greatest risk of exposure,” DeHudy told Infectious Diseases in Children.
Although it is widely believed that sharing headwear or personal grooming items with a person with head lice ensures infestation, fomite transfer is relatively uncommon, according to Krista Lauer, MD, national medical director of Larada Sciences.
“Less than 2% of cases of head lice happen by transfer through inanimate objects like hats, brushes and combs,” Lauer said. “Head lice cannot survive off the human scalp; while lice die within 48 hours of removal from the human head, studies have shown that they dehydrate and are non-viable within a few hours.”
However, the most enduring myth that pediatricians face regarding head lice is that the presence of lice eggs or “nits” is indicative of an active case of lice infestation, and that quarantining or excluding these children from school activities will prevent them from transmitting lice to others. Unfortunately, per CDC findings, by the time nits are discovered, the child in question has likely already had lice for more than a month, and now poses little risk to others.
Nevertheless, this belief has given rise to the “no-nit” policies still adopted by many school systems that require the removal of all nits, viable or not, before a child can return to school — policies that could exacerbate the stigma attached to head lice among children.
The residual cost of head lice policies
For many years, to limit head lice infestations spread among children and, subsequently, their families, health authorities and school systems across the U.S. have employed “no-nit” polices to bar children from attending school until all signs of an infestation have cleared, including nonviable nits left behind following successful treatment.
“Children may miss valuable learning time when they are excluded from school by “no-nit” policies or are sent home with head lice when they most likely have had head lice for some time,” Beth Mattey, MSN, RN, NCSN, president of the National Association of School Nurses (NASN), told Infectious Diseases in Children.
Despite the exhaustive and time-consuming efforts of school personnel to eradicate head lice infestations, a joint clinical report from the AAP Council on School Health and Committee on Infectious Diseases determined that many of the control measures, such as mass screening for nits, were not cost-effective and had no significant impact on the incidence of head lice in school communities.
Additionally, communication methods used under “no-nit” policies between school personnel and caregivers — the dreaded “head lice outbreak letters” — followed by a student’s conspicuous absenteeism were noted to worsen social stigmas, needlessly heighten community anxiety and infringe on a student’s rights to confidentiality.
Moreover, many of the protections intended through “no-nit” policies were scientifically unfounded “because the risk of head lice transmission is not that high,” Bocchini said. “Additionally, once treatment has started, the risk of transmission is virtually eliminated.”
As a result, the AAP no longer supports “no-nit” policies in U.S. schools, and the organization encourages pediatricians to educate parents, schools and communities that these policies should be abandoned.
“There is ample evidence that a no-nit policy does not change the rate of transmission of head lice,” Bocchini said. “[No-nit policies] are not recommended by the AAP, even though a number of school systems still use a “no-nit” policy.”
According to the 2015 AAP clinical report on head lice, a child diagnosed with head lice at school should remain there; there is no need to dismiss him or her immediately. A phone call or letter home to the affected child’s parents/caregivers should delineate the steps for quick and appropriate treatment. The NASN position statement on head lice echoes similar sentiments, discouraging the use of “no-nit” policies. The NASN’s position statement on the management of head lice also discourages no-nit policies.
“Students should not be restricted from school attendance,” Mattey said. “School policies should be evidence-based: abandon no-nit policies, allow the children to remain in class and notify parent/caregivers by the end of the school day.”
Throughout the process, all involved must protect the student. “As with other health issues at school, maintaining a student’s privacy and right to confidentiality is of utmost importance,” Mattey said.
Pediatricians play an important role in educating parents about head lice policies, giving parents the opportunity to be advocates for their children should the need arise.
“Parents need to know whether school head lice policies are consistent with current AAP/CDC recommendations; if not, the policies might wrongly exclude schoolchildren who are not at risk for spreading head lice,” Bocchini said. “Being aware of the head lice policies in practice means that parents can then advocate for their children.”
Although schools have been the focus of considerable interventions for head lice, summer vacation offers no respite — in fact, pediatricians will likely notice a spike in head lice infestations as many children attend summer camps or spend more time in daycare settings. Summer camp directors often encounter head lice infestations. In fact, according to the American Camp Association, the most common questions posed to their Camp Crisis Hotline are regarding head lice.
“It is clearly a topic that a lot of summer camps are dealing with,” DeHudy said. And yet, many camps have no formal policies established to address infestations when they arise.
DeHudy and colleagues surveyed the leadership of 500 camps about lice policy, management and training. They found that 30% of camps did not have a formal policy established; another 34% followed a no-nit policy, she said. Only 50% of camp leadership felt confident in staffers’ ability to properly diagnose this pest and 30% felt that staff members would appropriately treat an infestation.
With no formal policies in place, some camps opt to abide by a “no-nit” policy and send the child home.
DeHudy is hoping camps adopt a different approach. “Ideally, I would love for children to be able to stay at camp, but this would require camp staff to feel comfortable diagnosing, treating and preventing head lice,” she said. “It is important for pediatricians to reinforce to parents that they should familiarize themselves with whether their child’s summer camp has a head lice policy, and if so, what it is, because otherwise children might be coming home from camp a little earlier than expected.”
Treatment nits to pick
When it comes to managing a head lice infestation, the pediatrician plays a critical role. First, the physician can more easily make this difficult diagnosis, which requires finding a nit or seeing a louse moving on the scalp. “Sometimes that is hard to do,” Bocchini told Infectious Diseases in Children.
Also, misdiagnosis is fairly common — nits can be mistaken for other things such as dandruff or dried shampoo — leading to unnecessary treatment, according to Bocchini.
Liberal pediculicide overuse may have led to the growing problem of resistance to two commonly used first-line OTC treatments, permethrin lotion (Nix; MedTech) and pyrethrins combined with piperonyl butoxide (Rid; Bayer).
“Resistance to permethrin and pyrethrum/piperonyl butoxide by head lice has developed over time with normal, appropriate therapeutic use,” Edward A. Bell, PharmD, BCPS, professor of pharmacy practice at Drake University College of Pharmacy and Health Sciences said. “Historically, these medications have successfully cured infestations, and they may continue to have a therapeutic role when resistance is low or absent.”
However, recent research has found that the majority of head lice in the U.S. exhibit resistant genes to even these reliable medications. In a recent study published in the Journal of Medical Entomology, Gellatly and colleagues demonstrated that head lice are exhibiting an expanding knockdown resistance (kdr) to the insecticides used in OTC agents. After collecting samples from 138 sites in 48 states, the researchers found that 98% of head lice in 42 states were resistant.
“The frequencies of kdr-type mutations did not differ regardless of the human population size that the lice were collected from, indicating a uniformly high level of resistant alleles,” the researchers wrote.
Drug resistance is only one reason why first-line treatment may fail, however; another issue is failure to properly use the product. The OTC products require two applications, about 1 week apart. The second application is designed to kill any late-hatching eggs.
“If a parent applies the first application but the not the second, and they see lice a few days later, then they will say the drug did not work,” Bell said. “We have to be careful not to jump on that resistance bandwagon too quickly. We know resistance is out there — there is laboratory evidence — but we do not have good correlations with how that laboratory resistance affects clinical resistance.”
Still, it is important for pediatricians to know whether head lice in their area are showing signs of resistance. “Physicians who take care of children who have head lice in that area should have a feeling as to whether properly used over the counter therapies are working,” Bocchini said. “If they’re not, that may mean that there’s resistance in that area.”
In places where resistance is a problem, there are several prescription medications available, according to Bocchini.
The four FDA-approved prescription options available as second-line treatment include malathion (0.5%), benzyl alcohol 5%, ivermectin (0.5%) and spinosad (0.9% suspension).
Boasting efficacy rates of 80% to 90%, if used properly, these agents “should have a high cure rate,” Bocchini said. “If they don’t, then a second treatment or a treatment with a different therapy can be considered.”
No matter what treatment is selected, it is important that the pediatrician or primary care provider work with the family to ensure that the correct decisions are made.
And that is partly because some of these medications carry some risks. “While there are some prescription medications that are still effective, it is only a matter of time before lice develop resistance to these as well,” Lauer told Infectious Diseases in Children. “In addition, these are strong neurotoxic chemicals that we are applying to our children’s scalps, so while they are effective for the time being, there are some health concerns associated with their use.”
There are other, nonchemical ways to treat infestations as well. Given its inherent safety, pediatricians can recommend manual removal with a fine-tooth nit comb to address an infestation, although they should warn parents that it is laborious. “Finding all the nits and removing them is a tedious task,” Bocchini said.
Dehydration via heated air is another treatment option, according to Lauer. A 30-minute treatment with the FDA-approved AirAllé (Larada Sciences), followed by a post-treatment comb-out, kills nits and 99% of live lice. The certified operators apply the heat in an overlapping pattern to ensure that the entire scalp is treated. “Because, of course, if you leave two nits, you will have reinfestation,” Lauer said.
Although there are several effective products available, some parents may still prefer to pursue “natural” remedies, such as essential oils, petrolatum shampoo, mayonnaise or olive oil. While boasting no known harmful chemicals, alternate treatments are not necessarily safe and effective because they have not been subjected to rigorous testing through clinical trials.
“First, parents should be made aware that current recommended products are safe and are usually effective if used as recommended,” Bocchini said. “Parents also need to understand that alternate therapies are untested and thus we do not know whether they are effective. They are likely to have high failure rates. Parents also need to know that they should not utilize any potentially toxic materials.” — by Colleen Owens
To read the At Issue regarding drug-resistant head lice in the pediatric office, please click here.
- CDC. https://www.cdc.gov/parasites/lice/head/gen_info/faqs.html. Accessed March 16, 2017.
- Devore CD, et al. Pediatrics. doi: 10.1542/peds.2015-0746.
- DeHudy E, et al. Abstract #318305. Presented at: AAP National Conference and Exhibition; Oct. 22-25, 2016; San Francisco, California.
- Gellatly KJ, et al. J Med Entomol. doi: 10.1093/jme/tjw023.
- Parison JC, et al. Int J Dermatol. doi: 10.111/j.1365-4632.2011.05300.x.
- For more information:
- Joseph A. Bocchini Jr., MD, FAAP, can be reached at Louisiana State University Health Sciences Center, 1602 Kings Highway, Shreveport, LA 71103; email: email@example.com.
- Edward A. Bell, PharmD, BCPS, can be reached at Drake University College of Pharmacy and Health Sciences, Cline 106, 2507 University Ave, Des Moines, IA 50311-4505; email: firstname.lastname@example.org.
- Ashley DeHudy, MD, MPH, can be reached at the University of Michigan Mott Children’s Hospital through the University of Michigan Department of Public Relations at UMHSmedia@umich.edu.
- Krista Lauer, MD, can be reached at Larada Sciences Inc., 154 East Myrtle Ave., Suite 304, Murray, Utah 84107; email: email@example.com.
- Beth Mattey, MSN, RN, NCSN, can be reached at the National Association of School Nurses, 1100 Wayne Ave. #925, Silver Spring, MD 20910; email: firstname.lastname@example.org.
Disclosures: Bocchini, Bell, DeHudy, Lauer and Mattey report no relevant financial disclosures.