MEDLINE Abstracts: Head Lice

April 24, 2002

MEDLINE Abstracts: Head Lice

Comparative Efficacy of Treatments for Pediculosis Capitis Infestations: Update 2000

Meinking TL, Entzel P, Villar ME, Vicaria M, Lemard GA, Porcelain SL
Arch Dermatol. 2001;137:287-292

Objective: To evaluate the pediculicidal and ovicidal activity of 5 head lice products.
Design: In vitro pediculicidal and ovicidal product comparison.
Setting: Tropical field station in Panama.
Participants: Head lice and eggs were harvested from healthy children infested with Pediculus capitis.
Intervention: Within 2 hours of capture, lice were placed in continuous, direct contact with the pediculicide products and observed at regular intervals. Fresh, viable eggs were immersed in the pediculicides for 10 minutes, rinsed, air-dried, and incubated for 2 weeks.
Main Outcome Measures: Percentage of lice dead at regular observation intervals between 5 minutes and 3 hours of continuous exposure to the pediculicide and percentage of eggs not hatched after 2 weeks.
Results: All lice treated with Ovide lotion (0.5% malathion) were dead within 10 minutes and none of the eggs hatched. There was no significant change in the effectiveness of 0.5% malathion lotion or A-200 shampoo compared with the results of an earlier study (1986). There were significant declines in the pediculicidal activity of RID and the ovicidal activity of lindane. Nix (1% permethrin), which was not on the market at the time of the original study, killed lice in less than 30 minutes, and ovicidal activity ranged from 73% to 90% (diluted and undiluted, respectively).
Conclusions: Ovide lotion (0.5% malathion) was the fastest-killing pediculicide and the most effective ovicide. One percent lindane shampoo was the slowest-acting pediculicide and least effective ovicide. Nix was highly effective in both undiluted and diluted forms.

Head Lice Infestation: Single Drug Versus Combination Therapy With One Percent Permethrin and Trimethoprim/Sulfamethoxazole

Hipolito RB, Mallorca FG, Zuniga-Macaraig ZO, Apolinario PC, Wheeler-Sherman J
Pediatrics. 2001;107:E30

Background. Head lice infestation (HLI) is a vexing problem for pediatricians and families because lice are becoming resistant to approved antipediculosis agents.
Objective. This study compared the efficacy of 3 different treatments for HLI and determined whether combination therapy reduced treatment failures.
Design and Setting. A randomized, clinical trial performed in 3 private practices.
Participants. The population was children ranging in age from 2 to 13 years.
Methods. HLI was diagnosed by direct inspection of the hair and scalp. Children were assigned to 1 of 3 groups: 1) 1% permethrin creme rinse (1% PER; n = 39); 2) oral administration of trimethoprim/sulfamethoxazole (TMP/SMX; n = 36); and 3) a combination of 1% PER and TMP/SMX (n = 40). Follow-up visits were done 2 and 4 weeks later, and parents or caregivers of those who did not return were interviewed by telephone. If HLI was present at the 2-week follow-up, the child was retreated per their protocol. We defined successful treatment as the absence of adult lice and nymphal stage or eggs (nits). The presence of nits alone was not considered a treatment failure.
Results. At the 2-week follow-up visit, successful treatment for groups 1, 2, and 3 was 79.5%, 83%, and 95%, respectively. At the 4-week follow-up, successful treatment was 72%, 78%, and 92.5% for groups 1, 2, and 3, respectively. The absolute risk reduction for recurrence comparing group 1 versus group 2 was 6%, group 2 versus group 3 was 14%, and group 1 versus group 3 was 20%. No major adverse complications were seen in any treatment group.
Conclusion. Our findings indicate that a combination of 1% PER and TMP/SMX is an effective alternative therapy for HLI. We recommend that the dual therapy with 1% PER and oral TMP/SMX be used and reserved in cases of multiple treatment failures or suspected cases of lice-related resistance to therapy.

Head Lice Resistance: Itching That Just Won't Stop

Bartels CL, Peterson KE, Taylor KL
Ann Pharmacother. 2001;35:109-112

Objective: To evaluate the reports of resistance and cross-resistance to pediculicides in the head louse (Pediculus capitis), as well as the mechanisms involved.
Data Sources: Literature identified through a MEDLINE search (1966-April 2000) and through other secondary literature databases and/or bibliographies of pertinent articles.
Data Synthesis: Head lice infestation is a common, worldwide problem. The widespread use of insecticide treatments together with inadequate treatment methods has led to a concern regarding the potential development of resistant head lice. This literature review examines the reports of resistance of the head louse as well as the purported mechanisms involved.
Conclusions: Current research suggests that head lice resistance exists, but little is known regarding the actual incidence of this resistance or whether this incidence is increasing. More research is needed to assess the status of this problem. Proposed mechanisms for head lice resistance include knock-down resistance, glutathione S-transferase-based resistance, and monooxygenase-based resistance.

Clinical Evidence of Lice Resistance to Over-the-Counter Products

Burkhart CG CG, Burkhart CN
J Cutan Med Surg. 2000;4:199-201

Background: Over-the-counter insecticidal solutions continue to be the mainstream treatment for most cases of head lice. Recorded insecticidal activity 15 years ago was at 100%, with ovicidal kill at 80%. Recently scattered accounts of possible resistance have surfaced.
Objective: This article is to document the general consensus that head lice are becoming resistant to standard over-the-counter therapies.
Methods: Direct testing of lethality of adult lice with permethrin and pyrethroid was assessed.
Results: Present over-the-counter products proved to be successful in only 9 of 32 head lice tested (28% insecticidal activity).
Conclusions: Our series of cases further documents that over-the-counter head lice preparations no longer achieve high levels of insecticidal activity, suggesting increased resistance to these insecticides.

Scanning Electron Microscopy of Adult Head Lice (Pediculus humanus capitis) With Focus on Clinical Implications

Burkhart CN CN, Burkhart CG, Gunning WT
J Cutan Med Surg. 2000;4:181-185

Background: The incidence of head lice infestations in North America is escalating with an estimated 12 million cases of head lice per year despite the existence of insecticidal therapies.
Objective: To evaluate certain characteristics of the human head louse, including their chitinous structure, nymphal developmental stages, legs with claw adaptations, antennae with sensory perceptions, and spiracles by which oxygen exchange occurs, for assessment of possible means to control the spread and growth of this insect.
Methods: Scanning electron-microscopic examination of head lice was performed.
Results: Newer treatments of head lice must acknowledge defense mechanisms that are based on anatomic structure and physiologic characteristics, details of louse transmission, and the insects' ability to 'resurrect' after sham death.
Conclusions: An understanding of lice entomology is essential in the pursuit of novel means to control the lice epidemic.

Persistent Head Lice Following Multiple Treatments: Evidence for Insecticide Resistance in Pediculus Humanus Capitis

Bailey AM, Prociv P
Australas J Dermatol. 2000;41:250-254

Viable head lice were found on the scalps of two family members following multiple topical insecticide treatments. The possibility of reinfestation had been reliably excluded. Persistent infestation could be diagnosed only after cutting the hair and combing repeatedly, which allowed visualization of juvenile (nymphal) and adult lice. Insecticide-resistant headlouse infestations are probably much more common than is generally realised and may persist unnoticed, so that more aggressive approaches will be needed to eradicate these ectoparasites from individuals and communities.

Getting Ahead of Head Lice

de Berker D, Sinclair R
Australas J Dermatol. 2000;41:209-212

Dermatologists are the nominal experts in the management of head lice in Australia, yet many dermatologists infrequently treat patients with this condition. Most people are managed in the community by school nurses, local council health officers, pharmacists, paediatricians or general practitioners. Only a small number will present to the dermatologist and commonly these patients will have tried a variety of treatments and failed to respond. Resistance is reported to all of the currently available insecticide treatments and this makes management of this common community-acquired infestation more involved.

Efficacy of 1% Permethrin for the Treatment of Head Louse Infestations Among Kosovar Refugees

Manjrekar RR, Partridge SK, Korman AK, Barwick RS, Juranek DD
Mil Med. 2000;165:698-700

We assessed the prevalence of head louse infestation and the effectiveness of 1% permethrin against head lice in Kosovar refugees. A currently infested case was defined as a person with observable crawling lice (adults or nymphs) or a person with nits on the hair shaft within a quarter-inch of the scalp. Of the 1,051 refugees screened upon arrival in the United States, 107 (10%) were infested. Crawling lice (adults or nymphs) were observed on 62 (6%) of the individuals examined. Refugees with crawling lice were treated with a pediculicide containing 1% permethrin. Of these, 57 were reexamined the next day. Twenty of the 57 individuals were reexamined 7 days after treatment. No crawling lice were found on any of the refugees examined after treatment. We conclude that 1% permethrin treatment was effective in louse control in this refugee population.

Pediculocidal and Scabicidal Properties of Lippia Multiflora Essential Oil

Oladimeji FA, Orafidiya OO, Ogunniyi TA, Adewunmi TA
J Ethnopharmacol. 2000;72:305-311

The essential oil from the leaves of Lippia multiflora Moldenke (Verbenaceae) was tested for its pediculocidal and scabicidal activities against body lice, head lice and scabies' mites. The 'knockdown' times obtained for body lice and head lice using lippia oil preparations were comparatively shorter than those obtained using benzyl benzoate and Delvap Super, a brand of dichlorvos. The lethal effect of the lippia oil on head lice was increased when applied in an enclosed system that prevented volatilization of the oil while allowing maximum contact of the vapour with the headlice. A 20% v/v preparation of lippia oil applied to scabietic subjects for 5 consecutive days gave 100% cure compared with 87.5% cure obtained for benzyl benzoate preparation of the same concentration. The GC-MS analysis of oil revealed, among others, the presence of terpineol, alpha- and beta-pinene which are known to be lethal to body and head lice.

The Methodology and Operation of a Pilot Randomized Control Trial of the Effectiveness of the Bug Busting Method Against a Single Application Insecticide Product for Head Louse Treatment

Bingham P, Kirk S, Hill N, Figueroa J
Public Health. 2000;114:265-268

A Department of Health leaflet suggests two treatment methods for head lice: mechanical removal by wet combing; and insecticide lotion/rinses. However, there are no reports in the literature comparing the effectiveness of these two treatment methods and well controlled clinical trials of insecticide treatments are sparse. A pilot randomized control trial of the effectiveness of a specific method of wet combing, 'Bug Busting', against a single application of a proprietary insecticide product is reported. The difficulties of designing a trial are discussed and modifications that would allow a definitive trial to take place are suggested. The pilot study included enzyme analysis of lice for insecticide resistance status assessment.

Overdiagnosis and Consequent Mismanagement of Head Louse Infestations in North America

Pollack RJ, Kiszewski AE, Spielman A
Pediatr Infect Dis J. 2000;19:689-93; discussion 694

Background: Lay personnel and many health care workers in the United States believe that head louse infestations caused by Pediculus capitis are exceedingly transmissible and that infested children readily infest others. Schoolchildren therefore frequently become ostracized and remain so until no signs of their presumed infestations are evident. Repeated applications of pediculicidal product and chronic school absenteeism frequently result.
Methods: To determine how frequently louse-related exclusions from schools and applications of pediculicidal therapeutic regimens might be inappropriate, we invited health care providers as well as nonspecialized personnel to submit specimens to us that were associated with a diagnosis of pediculiasis. Each submission was then characterized microscopically.
Results: Health care professionals as well as nonspecialists frequently overdiagnose pediculiasis capitis and generally fail to distinguish active from extinct infestations. Noninfested children thereby become quarantined at least as often as infested children. Traditional anti-louse formulations are overapplied as frequently as are "alternative" formulations. Pediculicidal treatments are more frequently applied to non-infested children than to children who bear active infestations.
Conclusions: Pediculicidal treatments should be applied solely after living nymphal or adult lice or apparently viable eggs have been observed. Because health care providers as well as lay personnel generally misdiagnose pediculiasis, and because few symptoms and no direct infectious processes are known to result, we suggest that the practice of excluding presumably infested children from school may be more burdensome than the infestations themselves.

Comparison of Wet Combing With Malathion for Treatment of Head Lice in the UK: A Pragmatic Randomised Controlled Trial

Roberts RJ, Casey D, Morgan DA, Petrovic M
Lancet. 2000;12:540-544

Background: Concern about the effectiveness and toxicity of insecticide lotions has led to promotion of mechanical methods to remove head lice. We compared the effectiveness of "bug-busting" (wet combing with a fine-toothed comb) and malathion lotion.
Methods: We screened 4037 schoolchildren in two counties in Wales, UK (intermediate resistance to malathion). Of 167 found to have head lice, 81 (aged 3-14 years) were eligible to participate in a randomised controlled trial that compared mechanical removal of lice by a commercial kit every 3-4 days for 2 weeks with two applications of 0.5% malathion lotion 7 days apart; parents carried out both treatments. The outcome measure was the presence of live lice 7 days after the end of treatment. Analyses were by intention to treat.
Findings: 74 children completed the study and 72 were included in the analysis. The cure rate was 38% (12 of 32) for bug-busting and 78% (31 of 40) for malathion. Children assigned bug-busting were 2.8 (95% CI 1.5-5.2) times more likely than those assigned malathion to have lice at the end of treatment (p=0.0006).
Interpretation: Malathion lotion was twice as effective as bug-busting, even in an area with intermediate resistance. Policies advocating bug-busting as first-line treatment for head lice in the general population are inappropriate. Assessment of the outcome of treatment 1-2 weeks after completion is essential for successful management. Only about 50% of participants complied fully with treatment, so future trials should be pragmatic in design, avoid false incentives, and study representative samples of children.

The Challenge of Choosing a Pediculicide

Hensel P
Public Health Nurs. 2000;17:300-304

Head lice is the most frequently occurring communicable disease, except for the common cold, among children in the United States. The impact on a family facing the challenge of head lice is tremendous, ranging from emotional to financial distress. Challenges also face the health care provider and school personnel. Many over-the-counter preparations and prescription products are available to combat head lice. With the alleged advent of pediculicide-resistant head lice, many other products and applications not necessarily intended to treat head lice are being recommended. The purpose of this article is to outline the products and procedures currently being utilized and to provide a starting point for treating head lice.

Interventions for Treating Head Lice

Dodd CS
Cochrane Database Syst Rev. 2000:CD001165

Background:Infection with head lice is a widespread condition in developed and developing countries. Infection occurs most commonly in children, but also affects adults. If left untreated the condition can become intensely irritating and skin infections may occur if the bites are scratched.
Objectives: The aim of this review was to assess the effects of interventions for head lice.
Search Strategy: Trials register of The Cochrane Infectious Diseases Group; Medline; Embase; Science Citation Index; Biosis and Toxline; reference lists of relevant articles; pharmaceutical companies producing pediculicides (published and unpublished trials); UK and US Regulatory Authorities.
Selection Criteria: Randomised trials (published and unpublished) or trials using alternate allocation were sought which compared pediculicides with the same and different formulations of other pediculicides, and pediculicides with physical methods.
Data Collection And Analysis: Of the 70 identified studies, only three met the inclusion criteria and one is awaiting assessment. Two reviewers independently assessed trial quality. One reviewer extracted the data.
Main Results: We found no evidence that any one pediculicide has greater effect than another. The two studies comparing malathion and permethrin with their respective vehicles showed a higher cure rate for the active ingredient than the vehicle. The third study comparing synergised pyrethrins with permethrin showed their effects to be equivalent. Adverse effects were reported in a number of trials and were all minor, although reporting quality varied between trials.
Reviewer's Conclusions: Permethrin, synergised pyrethrin and malathion were effective in the treatment of head lice. However, the emergence of drug resistance since these trials were conducted means there is no direct contemporary evidence of the comparative effectiveness of these products. The 'best' choice will now depend on local resistance patterns. There is currently no evidence from trials to indicate the effectiveness of physical methods, such as combing/'BugBusting' or other chemical control methods such as the use of herbal treatments, when used in the curative treatment of head lice. Future trials should take into account the methodological recommendations that arise from this review.