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.

Importance of Follow-Up Microscopic Examination in Hospitalized Patients with Confirmed Scabies.

We investigated the duration of positive microscopic examination in hospitalized patients with confirmed scabies in an acute care hospital. We included hospitalized patients who were diagnosed with scabies between January 2015 and June 2019. From the study period, a total of 31 patients with confirmed scabies were identified. Median age was 75 years. Of a total of 31 patients with confirmed scabies, six were discharged or transferred before getting a negative microscopic test result. Of the remaining 25 patients with negative microscopic test results, the median duration from diagnosis to a negative microscopic test result was 14 days (interquartile range, 9-17). Given that nosocomial outbreaks lead to high workload and considerable resource consumption, adequate treatment, sufficient follow-up examination, and confirmation of cure are warranted before releasing contact isolation.

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.

Clinical Inquiry: What is the most effective treatment for scabies?

EVIDENCE-BASED ANSWER: Topical permethrin is the most effective treatment for classic scabies (strength of recommendation [SOR]: A, meta-analyses with consistent results). Topical lindane and crotamiton are inferior to permethrin but appear equivalent to each other and benzyl benzoate, sulfur, and natural synergized pyrethrins (SOR: B, limited randomized trials). Although not as effective as topical permethrin, oral ivermectin is an effective treatment compared with placebo (SOR: B, a single small randomized trial). Oral ivermectin may reduce the prevalence of scabies at one year in populations with endemic disease more than topical permethrin (SOR: B, a single randomized trial).

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.

Scabies Among Elderly Korean Patients with Histories of Leprosy.

A scabies epidemic, traced by the hospital-based surveillance system, was reported in a Korean leprosarium. A total of 200 symptomatic cases were found during 2012-2014 among 570 elderly former leprosy patients. Most of cases were classic type scabies (87%) and aged 75 years and older (72%). Surveillance system for early diagnosis and prompt intervention was applied and the scabies epidemic was controlled effectively in this long-term care facility.

Efficacy and safety of a lindane 1% treatment regimen for scabies, confirmed by dermoscopy-guided skin scraping with microscopic examination.

BACKGROUND: This is the first study investigating scabies treatment since 1992 to involve examination of patients with microscopically confirmed scabies. AIM: To assess the efficacy of 1% lindane cream in treating microscopically confirmed scabies, and to determine the utility of dermoscopy-guided skin scraping with microscopic examination (DSGSS-ME) in evaluating the efficacy of scabies treatment. METHODS: This retrospective study analysed patients treated for scabies between January 2012 and December 2013. From the hospital database, 287 cases of scabies were identified and 50 were enrolled in the study. Patients were treated with 1% lindane cream twice weekly (days 0 and 1) and were evaluated with DSGSS-ME on day 7. Treatment and evaluations were repeated once weekly until a negative DSGSS-ME result was obtained. RESULTS: The cumulative efficacy of lindane 1% cream was 40% (20/50) after 1 week, 88% (44/50) after 2 weeks and 98% (49/50) after 3 weeks of treatment. There was a statistically significant difference between the 1- and 2-week (P = 0.03), and 1- and 3-week (P = 0.02) treatments. A total of 90 post-treatment DSGSS-MEs were performed, with a sensitivity of 97.3% (95% CI 85.8-99.9) and a negative predictive value of 98.2% (95% CI 90.1-100). Specificity and positive predictive value were 100%, as this procedure cannot yield false-positive results, because it relies on finding mites, eggs or faeces. CONCLUSIONS: We suggest that a twice-weekly schedule (on consecutive days) of 1% lindane treatment lasting at least 2 weeks is required to clear scabies. DSGSS-ME appears to be a good method to evaluate the efficacy of scabies treatment. This study introduces a safe and effective method to treat scabies, and to accurately monitor infestation status in patients.

Treatment for crusted scabies: limitations and side effects of treatment with ivermectin.

Skin eruption with mild itching of the hands and feet developed in a man in his 90s 1 month after he was hospitalized following a traffic accident. Scabies was diagnosed in an attending nurse 3 months after the patient's hospitalization, and infection from the patient was suspected. Cornification of the patient's soles and marked hypertrophy of the nails of both feet were observed. After a large number of scabies mites were detected on microscopic examination, crusted scabies was diagnosed. The patient was given oral ivermectin, 6 mg, once per week for 3 weeks, and crotamiton topical ointment containing 30% benzyl benzoate was applied on the body from the neck down. However, because a large number of scabies mites were detected again on microscopic examination, the dose of ivermectin was increased to 12 mg and administered 3 times. One week after the sixth dose of ivermectin was administered, hemorrhagic scabs around the mouth and erosion of the tongue developed. Mucosal drug eruption was suspected, and eruptions around the mouth and on the tongue resolved within 1 week after ivermectin being discontinued. 1% gamma-benzene hexachloride ointment was applied topically on the body from the neck down once a week, crotamiton ointment containing benzyl benzoate was applied daily, and the hypertrophic parts of the nails were removed. The patient subsequently achieved a full recovery.

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.

Ivermectin vs. lindane in the treatment of scabies.

Scabies is commonly treated with acaricides but the treatment of choice is still controversial. This study aimed at comparing the efficacy of oral ivermectin vs. lindane lotion 1% for the treatment of scabies. Four hundred fourty patients with scabies were enrolled, and randomized into two groups: the first group received a single dose of oral ivermectin 200 microg/kg body weight, and the second group were treated with two applications of topical lindane lotion 1%, with a 1-week interval. Treatment was evaluated at intervals of 2 and 4 weeks, and if there was treatment failure at the 2-week follow-up, treatment was repeated. Single dose of oral ivermectin provided a cure rate of 63.6% at the 2-week follow-up, which increased to 81.8% at the 4-week follow-up after repeating the treatment. Treatment with two applications of lindane lotion 1%, with a 1-week interval between them, was effective in 45.4% of patients at the 2-week follow-up, which increased to 63.6% at the 4-week follow-up after this treatment was repeated. Single dose ivermectin was as effective as two applications of lindane lotion 1% at the 2-week follow-up. After repeating the treatment, ivermectin was superior to lindane lotion 1% at the 4-week follow up.

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.

Treatment of scabies: comparison of ivermectin vs. lindane lotion 1%.

Topical antiscabietics have poor compliance. This study aimed at comparing the efficacy and safety of oral ivermectin with topical lindane in treating scabies. In this clinical trial, 248 patients from 2 to 86 years of age were divided into two groups. Oral ivermectin was given to group A in a single dose of 200 µg/kg body weight. Group B received application of lindane lotion 1% twice at one-week interval. When there was no cure in two weeks, 2nd treatment was given with either drug in the respective group. A single dose of ivermectin provided a cure rate of 58.6% at two-week follow up, which increased to 92.7% with 2 doses at the end of 4-week interval. The application of lindane lotion 1% twice at one-week interval was effective in 44.3% of patients at two-week follow up, which increased to 71.7% after repeating the treatment for another two weeks. Single dose application of oral ivermectin was as effective as twice application of lindane lotion 1% at one-week interval. Two doses of ivermectin proved superior to lindane lotion 1% after repeating the treatment at 4-week follow up.

Recurrent bullous scabies.

BACKGROUND: scabies is a common infestation that usually presents as a pruriginous eruption consisting of erythematous papules, nodules, and excoriations. Diagnosis relies mostly on clinical features, including the identification of scabietic burrows. Several atypical clinical manifestations have been reported; bullous presentations are particularly rare and intriguing. OBJECTIVE: a case of recurrent bullous scabies is reported. METHODS AND RESULTS: an 87-year-old institutionalized woman developed a pruriginous eruption that mimicked bullous pemphigoid. Histopathologic examination revealed blistering at the subepidermal level and a mixed inflammatory infiltrate with numerous eosinophils. Scabies mites were identified on dermoscopy and on skin scrapings, allowing a diagnosis of bullous scabies. Despite effective treatment with topical lindane, failure to control scabies in her institution led to recurrences of her peculiar blistering infestation. Immunofluorescence studies were always negative. CONCLUSIONS: these observations underscore the mite's role in the pathogenesis of blister formation and illustrate current challenges in scabies' diagnosis and management.

Lindane toxicity in a 7 year old boy.

Lindane (gamma-benzene hexachloride) is widely used as a scabicide by general practitioners and dermatologists in Pakistan. We present a case of a 7 year old boy who had suffered from scabies 1 week ago, for which he was prescribed lindane along with other medications by a general practitioner. After 3 application of lindane the child began to experience Grand mal seizures, ataxia, weakness, incoordination and severe burning paresthesias. Lindane is known to cause neurotoxicity and for this it has been recommended as a 2nd line treatment for scabies by FDA.