Failure of scabies treatment: a systematic review and meta-analysis.

BACKGROUND: Treatment failure is considered to be an important factor in relation to the increase in scabies incidence over the last decade. However, the regional and temporal differences, in addition to the predictors of therapy failure, are unclear. OBJECTIVES: We aimed to conduct a systematic review of the prevalence of treatment failure in patients with scabies and investigation of associated factors. METHODS: We searched MEDLINE, EMBASE, CINAHL, Web of Science, Scopus, Global Health and the Cochrane Central Register of Controlled Trials from inception to August 2021 for randomized and quasi-randomized trials, in addition to observational studies that enrolled children or adults diagnosed with confirmed or clinical scabies treated with permethrin, ivermectin, crotamiton, benzyl benzoate, malathion, sulfur or lindane, and measured treatment failure or factors associated with treatment failure. We performed a random effects meta-analysis for all outcomes reported by at least two studies. RESULTS: A total of 147 studies were eligible for inclusion in the systematic review. The overall prevalence of treatment failure was 15.2% [95% confidence interval (CI) 12.9-17.6; I2 = 95.3%, moderate-certainty evidence] with regional differences between World Health Organization regions (P = 0.003) being highest in the Western Pacific region (26.9%, 95% CI 14.5-41.2). Oral ivermectin (11.8%, 95% CI 8.4-15.4), topical ivermectin (9.3%, 95% CI 5.1-14.3) and permethrin (10.8%, 95% CI 7.5-14.5) had relatively lower failure prevalence compared with the overall prevalence. Failure prevalence was lower in patients treated with two doses of oral ivermectin (7.1%, 95% CI 3.1-12.3) compared with those treated with one dose (15.2%, 95% CI 10.8-20.2; P = 0.021). Overall and permethrin treatment failure prevalence in the included studies (1983-2021) increased by 0.27% and 0.58% per year, respectively. Only three studies conducted a multivariable risk factor analysis; no studies assessed resistance. CONCLUSIONS: A second dose of ivermectin showed lower failure prevalence than single-dose ivermectin, which should be considered in all guidelines. The increase in treatment failure over time hints at decreasing mite susceptibility for several drugs, but reasons for failure are rarely assessed. Ideally, scabicide susceptibility testing should be implemented in future studies.

Efficacy and safety of antiscabietic agents: A systematic review and network meta-analysis of randomized controlled trials.

BACKGROUND: Many drugs have been used to treat scabies, but it is unclear which of them is the most efficacious. OBJECTIVE: To evaluate the comparative efficacy and safety of antiscabietic agents. METHODS: A systematic review of randomized controlled trials was conducted. Direct and network meta-analyses were applied to 13 antiscabietic agents on 3 outcomes (cure, persistent itching, and adverse events). Their probability of having highest efficacy and safety was estimated and ranked. RESULTS: A network meta-analysis of 52 trials including 9917 patients indicated that permethrin (the reference treatment) had a significantly higher cure rate than sulfur, malathion, lindane, crotamiton, and benzyl benzoate. Combination permethrin plus oral ivermectin had a nonsignificantly higher cure rate than permethrin. Combination permethrin plus oral ivermectin was ranked highest in terms of cure, topical ivermectin in terms of persistent itching, and synergized pyrethrins in terms of adverse events. On the basis of clustered ranking, permethrin, oral ivermectin, and synergized pyrethrins seemed to retain balance between cure and adverse events. LIMITATIONS: There are small numbers of trials and patients in some comparisons and a high risk of bias in some trials. CONCLUSION: There is no 1 treatment that ranked highest in all aspects. Physicians should consider the drug's efficacy and safety profiles, along with ease of administration.

Pediculosis capitis: ¿es algo realmente banal? / Pediculosis capitis: is it really an insignificant disease?

La pediculosis capitis es la infestación pediátrica más frecuente. Generalmente se considera una infestación banal y no se comentan las posibles complicaciones clínicamente relevantes. Se presenta el caso de una adolescente con historia de astenia, anemia moderada, importante adenopatía cervical y eosinofilia, finalmente achacada a la infestación por el parásito, no sospechada de entrada (AU)

Pediculosis capitis is the most common pediatric infestation. Generally, it is considered a minor infestation, and scientific literature rarely reports possible relevant clinical complications. Our aim is to present the case of an adolescent with asthenia, moderate anaemia, significant cervical lymphadenopathy and eosinophilia, which was discovered later that the parasite was the cause (AU)

Lice.

Pediculosis (capitis, corporis, and pubis) share well-known features: worldwide prevalence (involving millions of people annually); parasites inducing skin lesions directly, and indirectly as a result of itching and hypersensitivity to parasites; and treatment based on good entomological knowledge of the parasite and practical considerations (ie, most available treatments do not act on eggs and should be repeated, depending on the life cycle of the parasites). Infestations are spread most commonly by close contacts. Social stigma and persistent misconceptions complicate the implementation of appropriate management strategies. Head and pubic lice infestations are diagnosed by the visualization of insects or viable nits (eggs). Primary treatments are topical pediculicides (permethrin or malathion), used twice, but emergence of resistance against pediculicides has created the need of alternative treatments including topical or oral ivermectin. Pubic lice are treated the same as head lice, but this finding should prompt evaluation for other sexually transmitted diseases. Body lice infestation should be suspected when symptoms of generalized itching occur in persons who do not change or wash their clothing or bedding regularly; lice may be found in the seams of their clothing.Topically administered permethrin may help to eradicate body lice, but personal hygiene measures are essential for successful treatment. Environmental treatment is also necessary for the eradication of the infestation. Health care personnel who come into contact with this population need to be well informed of the facts in order to disseminate accurate information for diagnosis and management.

Scalp involvement by Sarcoptes scabiei var hominis resembling seborrhoeic dermatitis in two immunocompromised patients with systemic lupus erythematosus.

Scabies is a common condition in New Zealand but scalp infestation by the mite is not often considered. Topical treatments traditionally do not involve the scalp. We report two cases of immunocompromised patients with systemic lupus erythematosus (SLE) who had scalp infestation clinically mimicking seborrhoeic dermatitis.

Advancements in the treatment of head lice in pediatrics.

Head lice infestations occur commonly each year in children of all socioeconomic statuses. However, head lice have become more of a nuisance as resistance to first-line agents, such as permethrin 1% and pyrethrins, has increased. Newer topical products provide unique mechanisms of action without current signs of resistance. As with older agents, proper application of products must be emphasized to ensure that treatment is effective. In addition, nonpharmacologic measures should be taken to avoid reinfestation in the patient and to prevent the spread of lice to close personal contacts.

Safety and efficacy of a non-pesticide-based head lice treatment: results of a randomised comparative trial in children.

BACKGROUND/OBJECTIVES: Increasing resistance to pesticide-based head lice treatments has resulted in the need for alternative products to treat head lice infestations, but there are few clinical studies that have adequately tested these products. This multicentre, randomised, assessor-blind, parallel-group phase IV trial compared the safety and efficacy of a non-pesticide-based head lice shampoo with malathion foam in children. METHODS: This trial used strict entry criteria, standardised treatment and assessment regimes, sibling control and a primary efficacy end-point defined as the absence of live head lice 21 days after initiating treatment. Repeat insult patch tests were performed to further assess the safety of the non-pesticide-based shampoo. In vitro tests were used to assess its ovicidal and pediculicidal efficacy. RESULTS: A total of 216 children were enrolled, of whom 172 were per-protocol. The non-pesticide-based shampoo was significantly more effective than malathion foam for the intent-to-treat population (62.3 vs 40.4% louse-free, unadjusted P = 0.002; adjusted P = 0.003), as well as for the per-protocol population (67.8 vs 43.0% louse-free, unadjusted P = 0.001; adjusted P = 0.004). Adverse events were limited to itching or stinging. Patch testing with the non-pesticide-based shampoo resulted in no adverse reactions. In vitro tests using body lice demonstrated that the non-pesticide-based shampoo is ovicidal and pediculicidal. CONCLUSION: The non-pesticide-based shampoo is significantly more effective in eliminating head lice than malathion foam in children, while being associated with a low incidence of mild, transient adverse events.

Permethrin and malathion resistance in head lice: results of ex vivo and molecular assays.

BACKGROUND: Treatment of head lice infestation relies on the application of topical insecticides. Overuse of these products has led to the emergence of resistance to pyrethroids and malathion worldwide. Permethrin resistance in head lice is mostly conferred by the knockdown resistance (kdr) trait. OBJECTIVE: To evaluate the occurrence of permethrin- and malathion-resistant head lice in Paris. METHODS: A prospective survey was conducted in 74 elementary schools. Live lice collected on schoolchildren were randomly selected and submitted to ex vivo bioassays or underwent individual DNA extraction. A fragment of kdr-like gene was amplified and compared with wild-type sequences. RESULTS: Live head lice were detected in 574 children. Ex vivo assays showed no surviving lice after a 1-hour contact with malathion while most lice died after a 1-hour exposure to permethrin and piperonyl butoxide (85.7%, 95% confidence interval [CI]: 83.9-87.5). Among the 670 lice with workable DNA sequences, 661 lice (98.7%, 95% CI 97.7-99.3) had homozygous kdr mutations. LIMITATIONS: The findings of this large-scale survey of the occurrence of insecticide-resistant head lice indicated a major insecticide pressure in the study population, but it was not sufficient to draw conclusions about other populations. The presence of T917I-L920F mutations in kdr gene may not correlate with treatment failure in prospective studies. CONCLUSION: The high occurrence of kdr mutant allele suggests that insecticide resistance was already strongly established in the studied population. This finding must be interpreted with caution as it may not be predictive of treatment failure.

[Management of lice infestations, recommendations for 2012]. / Prise en charge des pédiculoses en 2012.

Pediculosis is the most frequent and contagious ectoparasitic infestation in human, particularly in children from 3 to 8 years of age. Epidemics are observed from time to time, in schools or in adults in prisons. Even though benign, these infections remain unpleasant and can have an important psyco-social impact. Since a few years, caregivers have to face increasing problems while treating lice: appearance of insecticide resistances, lindane's withdrawal from the market and the marketing of new products which are not always well evaluated. This article offers first recalls about pediculoses and then a sum up of the different available treatments with an evidence based management strategy.

Clinical response and safety of malathion shampoo for treatment of head lice in a primary school.

OBJECTIVE: Help eradicate or at least alleviating head lice in a primary school with malathion shampoo and to study clinical response and safety of malathion shampoo. MATERIAL AND METHOD: All students were examined by using a fine-toothed lice comb to help detect live lice. Direct visual examination and the collection of nits for microscopic examination were performed to differentiate viable nits from empty nits. Diagnosis of head lice was made by the presence of lice. All students that had lice and/or nits were treated with malathion shampoo. Malathion shampoo was also provided for all family members. Pediculocidal efficacy was by the presence or absence of live lice. Blood for red blood cell cholinesterase activity was drawn in 32 volunteers before treatment and after the second treatment. RESULTS: At the first visit, 629 students were examined and 48 students had live head lice. The infestation rate was 13% in girls and 1.3% in boys. The cure rate was 93% after the first treatment. The reported side effects were nausea, a burning sensation, and irritation that was found in five (4%), 10 (7%) and three (2%) students respectively. The mean of RBC cholinesterase activity before and after two applications showed significant changes (p = 0.03). It was -7.5 +/- 4.1% reduction from the initial, but all were in the normal range. There was no report of clinical manifestation of malathion toxicity. CONCLUSION: Malathion shampoo is safe and effective in the treatment of head lice. There is significant skin absorption so a scalp examination for head lice should be done before subsequent application to avoid unnecessary exposure.

A randomized, assessor-blind, parallel-group, multicentre, phase IV comparative trial of a suffocant compared with malathion in the treatment of head lice in children.

BACKGROUND/OBJECTIVES: There are concerns about the effectiveness of head lice treatments because of increasing resistance and safety. This trial compared the safety and efficacy of a suffocant-based head lice treatment to malathion in children. METHODS: The trial used strict entry criteria, standardized treatment and assessment regimens, sibling treatment where appropriate and a primary efficacy end-point defined as the absence of live head lice. RESULTS: A total of 216 children were enrolled. One hundred and sixty-nine were per-protocol. The suffocant was significantly more effective than malathion for the intention-to-treat population (53.9% vs 40.4% louse-free, unadjusted P = 0.052; adjusted P = 0.024), as well as for the per-protocol population (57.8% vs 43.0% louse-free, unadjusted P = 0.054; adjusted P = 0.045). Adverse events were limited to itching or stinging and there were no serious or systemic adverse events. Repeat insult patch testing with the suffocant resulted in no adverse reactions. In vitro tests confirmed that the suffocant is a potent ovicide and pediculicide with 100% mortality of eggs and lice following a 20-min contact time. CONCLUSIONS: The suffocant is shown to be significantly more effective in eliminating head lice than malathion in children, while being associated with a low incidence of mild, transient adverse events.

Oral ivermectin versus malathion lotion for difficult-to-treat head lice.

BACKGROUND: Head-lice infestation is prevalent worldwide, especially in children 3 to 11 years old. Topical insecticides (i.e., pyrethroids and malathion) used as a lotion, applied twice at an interval of 7 to 11 days, are typically used for treatment. Resistance of lice to insecticides, particularly pyrethroids, results in treatment failure. The efficacy of alternative agents is controversial. METHODS: We conducted a multicenter, cluster-randomized, double-blind, double-dummy, controlled trial comparing oral ivermectin (at a dose of 400 microg per kilogram of body weight) with 0.5% malathion lotion, each given on days 1 and 8, for patients with live lice not eradicated by topical insecticide used 2 to 6 weeks before enrollment. The cluster was defined as the household. Infestation was confirmed and monitored by means of fine-toothed combing. Patients were at least 2 years of age and weighed at least 15 kg; all were treated at the study sites. The primary end point was the absence of head lice on day 15. RESULTS: A total of 812 patients from 376 households were randomly assigned to receive either ivermectin or malathion. In the intention-to-treat population, 95.2% of patients receiving ivermectin were lice-free on day 15, as compared with 85.0% of those receiving malathion (absolute difference, 10.2 percentage points; 95% confidence interval [CI], 4.6 to 15.7; P<0.001). In the per-protocol population, 97.1% of patients in the ivermectin group were lice-free on day 15, as compared with 89.8% of those in the malathion group (absolute difference, 7.3 percentage points; 95% CI, 2.8 to 11.8; P=0.002). There were no significant differences in the frequencies of adverse events between the two treatment groups. CONCLUSIONS: For difficult-to-treat head-lice infestation, oral ivermectin, given twice at a 7-day interval, had superior efficacy as compared with topical 0.5% malathion lotion, a finding that suggests that it could be an alternative treatment. (ClinicalTrials.gov number, NCT00819520.)

Head lice treatments and school policies in the US in an era of emerging resistance: a cost-effectiveness analysis.

BACKGROUND: Head lice are a common infection in school-age children worldwide. Several authorities in the US have recommended different treatments and school policies in order to control this disease. Recent concerns of emerging lice resistance worldwide raise the necessity to reassess the current recommendations. OBJECTIVES: To perform a cost-effectiveness analysis (from the US caregiver perspective) of three head lice treatments commonly used in the US, permethrin 1%, malathion 0.5% and the lice comb, in order to evaluate the cost effectiveness of different treatments in the current era, and to explore the effect of different factors in this analysis. METHODS: We used a decision-tree model to represent the costs and effectiveness of the different treatment strategies. A patient/caregiver perspective was applied, with a time horizon of 2 weeks. Probabilities of treatment success or failure of the three treatments were based on the literature. Effectiveness was measured as the successful eradication of head lice, and costs - including the costs of the treatment, the physician co-pay and the costs of days out of school - were calculated. One-way and multi-way analyses were performed using decision analysis software (Treeage Pro Healthcare 2008). RESULTS: Combing was dominated by permethrin 1%. The incremental cost-effectiveness ratio of malathion 0.5% versus permethrin 1% was $US161.75 per cure. For caregivers whose willingness to pay is <$US161.75 per cure, permethrin 1% is the most cost-effective option. For those with a willingness to pay of > or =$US161.75 per cure malathion 1% may offer the highest net monetary benefit. Twenty percent of the uncertainty in the model is due to variation in permethrin 1% resistance, and approximately 73% of the total variability of the model is attributed to the number of days the student has to be out of school because of the school's policy. CONCLUSIONS: Our study suggests that permethrin 1% was the most cost-effective treatment for those with a willingness to pay of <$US162 per cure. Sensitivity of lice to permethrin and the specific school head lice policy had major effects on the model. Thus, informing communities in a given geographical area about the degree of head lice resistance and sensitivity is necessary in order for the public to make a rational decision regarding treatment. Schools' head lice policies have a major effect on the cost of head lice treatments.

Malathion for head lice and scabies: treatment and safety considerations.

Malathion is an under-recognized and under-utilized therapy for head lice and scabies largely due to misperceptions about its safety profile. Specifically, its pure form as it exists in pharmaceutical preparations is non-toxic to humans in the low doses available. While labeled for ages six and up, recent studies showed no cholinesterase inhibition in head lice patients aged two-to-six treated with malathion. Flammability of malathion in isopropyl alcohol has reportedly resulted in human injury once in over one million prescriptions filled. Recent efficacy studies of malathion in United States (U.S.) head lice demonstrate efficacy rates of 97-98%. In the present era of permethrin and lindane resistance to head lice, malathion is a first-line option. For scabies, it is a reasonable alternative to permethrin 5% cream, especially when treatment of the scalp or hairy areas is desired.

Head lice treatments: Searching for the path of least resistance.

Based on the dialogue "Head lice" between Drs Kimberly D. Morel and Stephen Stone. Dialogues in Dermatology, a monthly audio program from the American Academy of Dermatology, contains discussions between dermatologists on timely topics. Commentaries from Dialogues Editor-in-Chief Warren R. Heymann, MD, are provided after each discussion as a topic summary and are provided here as a special service to readers of the Journal of the American Academy of Dermatology.