International recommendations for an effective control of head louse infestations.

Head louse infestations continue to be a concern of public health in most countries, including the most developed ones. The present recommendations are intended to inform and stress the role and impact of the different authorities, institutions, industry, and the public in the control of head lice in order to reduce the prevalence of this parasite. We encourage health authorities to pursue more effective methods to correctly identify such infestations, and evaluate existing and new pediculicides, medical devices, louse repellents, and louse- and nit-removal remedies. Pediculicides and medical devices must have verifiable claims in the instructions for use and should be tested periodically to document current levels of resistance by lice to the active ingredients and to the formulated products. Where the prevalence of lice is claimed to be epidemic, children should be periodically evaluated objectively to document the actual level of prevalence. Continuing education for health providers and the general population promises to correct misinformation regarding the biology, prevention, and management of lice. Parents should regularly inspect their children for head lice and treat as necessary. Health authorities are encouraged to eliminate policies and practices that rely upon school exclusion as a means to reduce incidence and prevalence, e.g., the 'no-nit' policy which lacks scientific justification, and are counterproductive to the health and welfare of children.

Management of Head Louse Infestations in the United States-A Literature Review.

UNLABELLED: Head lice are a source of scalp irritation, social disruption, and loss of school time. Health care providers need authoritative information to help avoid the costs and risks of ineffective treatment. A review was completed to provide relevant information on infestation treatments available in the United States. Three major biomedical databases were searched from 1985, when current products were first available, to 2014, focusing on U.S. REPORTS: A total of 579 references remained after duplicates were removed. A search of the U.S. Food and Drug Administration website and labels of approved products were reviewed. A marked decline in the effectiveness of permethrin and synergized pyrethrins was found, probably because of resistance arising from widespread and indiscriminate use, and the emergence of knockdown resistance mutations. The potential toxicity of lindane in the setting of readily available, safer, and more effective alternatives, should limit its use. Prescription products shown to be safe and effective with a single application, without nit combing, are topical ivermectin, malathion, and spinosad, whereas benzyl alcohol requires two applications. Home remedies such as mayonnaise, and essential oils, have not been demonstrated to be safe or effective, and may carry potential for severe adverse events. The high risk of failure of over-the-counter treatments in eliminating head louse infestations drives a need for health care provider recognition of the limitations of current treatments and for judicious use of treatments that remain effective.

Assessment of the safety and efficacy of three concentrations of topical ivermectin lotion as a treatment for head lice infestation.

BACKGROUND: Ivermectin is a broad-spectrum parasiticide in widespread systemic use, including as an off-label treatment for head lice infestation. The potential of the topical use of ivermectin as a treatment for head lice infestation was suggested by an in vitro report of a novel lotion formulation. OBJECTIVES: This study investigated the relative effectiveness of three ivermectin lotion concentrations (0.15, 0.25, and 0.5%) compared with vehicle placebo in eliminating head lice infestation. METHODS: In this randomized, blinded study, 78 head lice-infested subjects, aged 2-62 years, received a single, 10-minute application of product on day 1. Evaluations were completed at two and six hours post-application, and on days 2, 8 (±1), and 15 (+2). Safety was assessed according to the evaluations of trained observers and adverse event (AE) reports. Efficacy was assessed according to scalp and hair examinations. RESULTS: Compared with placebo, all ivermectin concentrations resulted in the statistically significant (P ≤ 0.003) eradication of head lice through to day 15, with the highest level of eradication (73.7%) in subjects who received the 0.5% concentration. The severity of pruritus decreased from baseline in all treatment groups, including the placebo group, from six hours post-treatment to day 15, with the greatest reduction in the 0.5% concentration group. No ocular irritation was observed. All three ivermectin treatment strengths and vehicle were well tolerated. CONCLUSIONS: A single application of a 0.5% concentration of this ivermectin lotion formulation shows promise as a safe and effective treatment for head lice infestation and the associated signs of pruritus.

International guidelines for clinical trials with pediculicides.

Pediculosis capitis, infestation with head lice, is common in all human societies. Chemical pediculicides are often used to control head louse infestations, particularly in wealthy communities. A significant number of different protocols have been used to test the efficacy and safety of pediculicides in clinical trials; this constrains scientific comparison of the evidence for efficacy of the different pediculicides. Here we recommend protocols for clinical trials of the efficacy and safety of single-, two-, and three-treatment interventions.

The clinical trials supporting benzyl alcohol lotion 5% (Ulesfia): a safe and effective topical treatment for head lice (pediculosis humanus capitis).

Benzyl alcohol lotion 5% (BAL 5%) is a non-neurotoxic topical head lice treatment that is safe and effective in children as young as 6 months of age. The safety and efficacy of this pediculicide has been studied in 695 (confirm number) subjects in all phases of clinical development. Scanning electron micrographs (SEM) demonstrated that the active agent appears to stun the breathing spiracles open, enabling the vehicle to penetrate the respiratory mechanism (spiracles), therefore asphyxiating the lice. Initial phase II trials compared this novel product to RID using identical volumes of treatment (4 oz/application) and yielding, almost, identical efficacy. This outcome pointed to the significant importance of completely saturating the hair with the product in order to achieve maximum treatment success. A second phase II trial, which allowed the use of sufficient product to saturate the hair, resulted in 100% efficacy after both 10 and 30 minute treatments. A third phase II trial verified an effective dose. Phase III trials compared BAL 5% to vehicle placebo for two 10-minute applications. It proved to be safe and effective (p < 0.001) for treatment of head lice and is the first FDA-approved non-neurotoxic lice treatment, now available in the United States as Ulesfia lotion.

A randomized, investigator-blinded, time-ranging study of the comparative efficacy of 0.5% malathion gel versus Ovide Lotion (0.5% malathion) or Nix Crème Rinse (1% permethrin) used as labeled, for the treatment of head lice.

One hundred seventy-two subjects with head lice participated in a five-way, investigator-blinded, parallel-group, active-controlled study comparing 0.5% malathion gel (30, 60, and 90 minutes applications), Ovide Lotion (0.5% malathion), and Nix Crème Rinse (1% permethrin). All subjects were treated on day 1. Participants were reevaluated at day 8 +/- 1 and those with live lice were retreated with the same product, for the same duration as day 1. Cure, defined as the absence of live lice, was evaluated 14 +/- 2 days after the last treatment and 161 subjects completed the study according to the protocol. Compared to Nix, treatment success rates were statistically superior for all malathion gel and Ovide groups. Retreatment rate for Nix was 70%, which was statistically more than the malathion groups. The highest treatment success rates were observed for the 30-minute malathion gel (98% intent-to-treat and 100% per-protocol [PP]) and the 8 to 12 hour Ovide application (97% intent-to-treat and 100% PP). In conclusion, the 30-minute malathion gel, which contains the same ingredients and concentrations as Ovide, provides comparable efficacy, offers increased safety and is more cosmetically acceptable than Ovide.

Efficacy of a reduced application time of Ovide lotion (0.5% malathion) compared to Nix creme rinse (1% permethrin) for the treatment of head lice.

Our objective was to conduct a randomized, investigator-blinded evaluation of the pediculicidal and ovicidal activity of a reduced application time (20 minutes) of Ovide (0.5% malathion) compared to Nix (1% permethrin) in a south Florida population infested with Pediculus humanus capitis. Either Ovide or Nix was applied according to the label instructions. However, Ovide application time was reduced to 20 minutes. At day 8, subjects with live lice were re-treated with the same product and procedure as on day 1. Ovicidal and pediculicidal efficacy were evaluated at days 8 and 15. A subject free of lice and viable eggs at day 15 was considered to be a treatment success. Percent efficacy was calculated using the number of subjects free of lice and viable eggs per total number of subjects treated. We found that a 20-minute application of Ovide was significantly more pediculicidal and ovicidal (98%) compared to Nix (55%) at day 15 (p < 0.0001). The percentage of Ovide subjects who required treatment at day 8 was half that of the Nix group. The reinfestation rate was 0% with Ovide and 33% with Nix. In conclusion, a 20-minute treatment with Ovide, instead of the approved 8- to 12-hour application, cured 40 of 41 subjects (98%), demonstrating superior efficacy to Nix. The poor efficacy of Nix confirms the resistance of head lice to permethrin in south Florida.

Clinical update on resistance and treatment of Pediculosis capitis.

The anatomy and physiology of head lice make them extremely adaptable to their human hosts but also difficult to eradicate. Their coloring and small size make them difficult to see, and the larvae, or nymphs, have multiple exoskeletons for protection. When exposed to pediculicides, a nymph can shed its outer exoskeleton and receive only a sublethal dose. Through natural selection, head lice have developed resistance to commonly used pediculicides, making it increasingly difficult to eliminate infestations. Other contributors to resistance include changes in formulations of pediculicides and improper use. Over the last 20 years, the efficacy of pyrethrins has declined because of necessary safety changes in formulations and unintentional effects of new packaging on chemical components of these products. Pediculicides designed to be applied to wet hair may become too diluted to produce the desired effect. Patients also may use too little product to conserve costs. The combination of decreased product efficacy and exposure of head lice to diluted or insufficient amounts of pediculicides has reduced their effectiveness substantially. Studies comparing the current efficacy of several over-the-counter and prescription pediculicides with effectiveness in the 1980s has shown that OVIDE (malathion) Lotion, 0.5% is the only product that has retained its efficacy over time. The efficacy of over-the-counter pyrethrin products had declined significantly, and lindane, another prescription product, was least effective of all products tested both in the 1980s and in more recent studies. In addition to retaining its efficacy, malathion 0.5% also is effective when applied for only 20 minutes. The shorter application time is safer for children and also decreases the likelihood that residual product remains in the hair, further contributing to resistance.

Changing paradigms in parasitic infections: common dermatological helminthic infections and cutaneous myiasis.

Parasitic diseases caused by helminths, or worms, account for billions of human infections worldwide. Although most human pathogens caused by these organisms are infrequent in the United States, skin manifestations of parasitic diseases are being seen much more frequently in dermatologists' offices due to the increase in immigration and travel. Helminths are notable for their complicated lifecycles often including consecutive developmental phases, in separate hosts or in a free-living state. These parasitic organisms are usually macroscopic, multicellular organisms, and do not breed within their mammalian hosts. Notably, many helminthic diseases present with dermatologic signs and symptoms including skin nodules, cysts, migratory skin lesions, and pruritus. In this section, we discuss cutaneous myiasis as well as the four most common nematode dermatologic conditions seen in the United States.

Ivermectin.

Ivermectin is a potent antiparasitic drug and the first commercially available member of a new class of drugs (macrocyclic lactones) that has been approved for human use. Ivermectin has already proven to be highly effective in the elimination of river blindness as a public health burden. Side effects have been minor, and patient acceptance is good. Promising results in off-label applications for ectoparasitic infestations are increasingly important as resistance to topical therapy becomes more prevalent Ivermectin represents an advance in the therapeutic armamentarium and should be considered in appropriate cases.

An observer-blinded study of 1% permethrin creme rinse with and without adjunctive combing in patients with head lice.

OBJECTIVES: To determine if NIX (Warner Lambert Healthcare, Morris Plains, NJ) 1% Permethrin Creme Rinse Lice Treatment (1% PLT) without combing will effectively treat >/=95% of patients on day 2 or on day 15; to determine whether combing influences efficacy. STUDY DESIGN: A randomized, observer-blinded study enrolled 95 infested adults and children. All patients were treated with 1% PLT on day 1 and, if still infested, on day 8. One third of households were randomized to the combing group and two thirds to the no-combing group. Efficacy was assessed by: (1) visual inspection on days 1, 2, 8, 9, and 15 and, (2) shampooing/straining on days 2, 9, and 15. The target efficacy was 95%. RESULTS: In the no-combing group, the lice-free rate was 83.1% on day 2 (95% CI, 71.0-91.6), 45.8% on day 8 (before second treatment) (95% CI, 32.7-59.2), 77.6% on day 9 (95% CI, 64.7-87.5), and 78.3% on day 15 (95% CI, 65.8-87.9). Adjunctive combing did not improve efficacy on any day. CONCLUSIONS: In this population, 1% PLT was significantly less than 95% effective and suggests resistance to 1% PLT. The failure of nit removal combing by nonprofessional caregivers to improve efficacy demonstrates the unreliability of combing as adjunctive treatment in this setting.

Comparative in vitro pediculicidal efficacy of treatments in a resistant head lice population in the United States.

OBJECTIVE: To compare the pediculicidal activity of 5 head lice products available in the United States on head lice from south Florida. DESIGN: In vitro pediculicidal product comparison. SETTING: Lice Source Services, Inc, located in Plantation, Fla, a clinic for the treatment and grooming of individuals with pediculosis capitis. PARTICIPANTS: Head lice were collected from healthy clients with Pediculus capitis that came to Lice Source Services, Inc, to seek their services. INTERVENTIONS: Within 2 to 6 hours of capture, lice were placed in continuous direct contact with the pediculicide products and observed at regular intervals. Results were compared with findings of a recent study of a treatment-sensitive population of head lice conducted in Panama. MAIN OUTCOME MEASURE: Percentage of lice dead at regular observation intervals between 5 minutes and 3 hours of continuous exposure to the pediculicides. RESULTS: Two prescription products, Ovide lotion (0.5% malathion) and 1% lindane shampoo, were ranked in the same order as in 2 previous studies (first and last, respectively). The order of effectiveness from most to least effective was as follows: Ovide lotion, A-200 shampoo (a natural pyrethrin product synergized with piperonyl butoxide), undiluted Nix (1% permethrin), diluted Nix, RID (a natural pyrethrin product synergized with piperonyl butoxide), and 1% lindane shampoo. CONCLUSIONS: There were statistically significant differences in the efficacy of all the products when compared with the results found in the recent study in Panama, except for Ovide lotion. Of those tested, Ovide was the only pediculicide in the United States that had not become less effective. The difference in efficacy of 1% lindane, Nix, and pyrethrins between the Panama and Florida studies supports the argument that some head lice in the United States have become resistant to these treatments.