Scabies in the age of increasing drug resistance

Ectoparasites Infestation to Small Ruminants and Practical Attitudes among Farmers toward Acaricides Treatment in Central Region of Java, Indonesia

Ectoparasite infestations are one of the major problems affecting goat and sheep farming. Disease resulting from these infestations can cause changes in physical appearance, such as severe lesions on the skin, and economic consequences in the form of significantly reduced selling prices. This study aimed to determine the prevalence of ectoparasites in the Boyolali district, Central Java, Indonesia. A total of 651 sheep and goats were surveyed in this study. The parasites were collected via skin scraping, twister, or manually from clinically infected goats and sheep in traditional farms. All of the ectoparasites collected were successfully identified. The prevalence of ectoparasites in ruminants in Boyolali was 97.8% (637/651). The species make-up was as follows: Bovicola caprae 97.8% (637/651), Linognathus africanus 39% (254/651), Haemaphysalis bispinosa 3.5% (23/651), Ctenocephalides spp. 0.2% (1/651), and Sarcoptes scabiei 5.2% (34/651). The predilection sites were in the face, ear, and leg areas, and in the axillary, dorsal, abdomen, and scrotum regions of the surveyed animals. An evaluation of farmers' attitudes to ectoparasites was performed using a questionnaire. The findings of this study imply that animals in the investigated area are highly exposed to ectoparasite infestations. Given the importance of ectoparasites in both livestock and human communities, specifically in the health domain, more research into appropriate control strategies is necessary.

Comparison of topical permethrin 5% vs. benzyl benzoate 25% treatment in scabies: a double-blinded randomized controlled trial

BACKGROUND

Scabies is a pruritic parasitic infestation of the skin. High-income countries have reported an increasing incidence over the last few years. Studies have indicated a reduction in the sensitivity of scabies mites to the standard treatment of choice, topical permethrin 5%.

OBJECTIVES

To evaluate in a head-to-head manner the efficacy of two topical scabicides [permethrin 5% and benzyl benzoate 25% (BB)] in the treatment of scabies using the same administration modality; and to address potential confounding factors such as incorrectly performed treatment and hygiene measures.

METHODS

In total, 110 patients with dermoscopy-verified scabies infestation were enrolled and randomized into two equally sized groups in a double-blinded manner. Fifty-five received topical permethrin 5% and 55 received topical BB 25%, both for daily use over a period of three consecutive days. Treatment outcome was evaluated by dermoscopy at a 3-week follow-up visit.

RESULTS

Treatment resulted in a dermoscopy-verified cure rate of 27% in the permethrin group and 87% in the BB group. The tolerability and safety profile of permethrin 5% cream was excellent, while the BB emulsion produced a burning sensation in 43% of patients.

CONCLUSIONS

Topical permethrin demonstrated a lack of efficacy in the majority of scabies cases, whereas BB demonstrated an excellent cure rate and reasonable tolerability. Considering the reduced sensitivity of scabies mites to permethrin 5%, our results suggest that BB is an appropriate first-line therapy in the treatment of scabies.

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.

Detection of a knockdown mutation in the voltage-sensitive sodium channel associated with permethrin tolerance in Sarcoptes scabiei var. hominis mites

BACKGROUND

Increasing evidence has sparked a debate on the loss of sensitivity of scabies mites to conventional permethrin therapy. Mutations in the voltage-sensitive sodium channels (VSSC) were associated with knockdown resistance (kdr) in many arthropods, but have never been identified in Sarcoptes scabiei variatio (var.) hominis mites.

OBJECTIVES

To identify factors contributing to therapy failure.

METHODS

Sixty-seven mites were collected from 64 scabies-infested patients in Vienna, Austria, of whom 85.9% were refractory to prior permethrin-based treatments, and genotyped for the presence of nucleotide polymorphisms in Domain II of the VSSC, known to be associated with kdr. Information regarding previous antiscabietic therapies, decontamination procedures and possible re-infestations by contacts as well as the response to re-imposed therapies were obtained.

RESULTS

Sequence alignment comparisons revealed previously unidentified mutations in the coding region of Domain II of the VSSC. A novel A1663T transversion was detected in 97.0% of the mites, resulting in a non-synonymous substitution from methionine to leucine, M918L, a mutation known to confer kdr in other arthropods. In addition, a synonymous G1659A transition was identified in one mite, which otherwise showed a nucleotide sequence identical to the wild-type reference. No major inconsistencies were observed within the previous therapeutic and decontamination procedures, which could have accounted for the observed non-responsiveness to permethrin-based therapies. Subsequent cure of infestation was achieved in 65.6% of the participants, predominantly by combination therapies with topical permethrin and systemic ivermectin. However, in 14.6% of the cured cases, permethrin monotherapy sufficed for eradication of scabies, albeit in some cases prolonged exposure was necessary.

CONCLUSIONS

The kdr-associated M918L mutation in the VSSC gene has now emerged in S. scabiei var. hominis mites. Hence, loss of sensitivity to permethrin due to kdr-type resistance may be more prevalent than anticipated and may be decisive for the therapy responsiveness of scabies-infested patients.

Permethrin-unresponsive scabies in London, UK: a wake-up call

Failure to respond to permethrin, the most widely prescribed first-line therapy for scabies, has been increasingly reported in recent years in a number of countries. However, its true scale and relation to verifiable permethrin resistance is currently unknown. We present a case of scabies associated with scabetic nodules in which a lack of response to topical permethrin treatment was evident.

The current available diagnostic tools and treatments of scabies and scabies variants: An updated narrative review

Scabies is a neglected tropical disease that continues to have global impacts and long-term health consequences. It is caused by the mite Sarcoptes scabei var. hominis, which is an obligate ectoparasite that lives in the epidermis of the human skin. Scabies is common in poor communities due to overcrowding in places like old age homes, prisons, and homeless and displaced children. However, developed countries are also susceptible to scabies infestations, such as in institutional outbreaks or small epidemics under war conditions or during natural disasters. The diagnosis of scabies may be assisted by invasive and noninvasive tools; However, the history and examination findings are usually adequate to confirm the clinical suspicion. Here, we present an updated review of scabies by focusing on the diagnostic approaches, treatment, and prevention of scabies.

Study of the Use of Permethrin 5% Cream in Galicia (Spain) between 2018 and 2021

Drug utilization studies can provide direct insights into how a drug is used in real-world conditions and can give a rough estimate of the proportion of the study population treated with it. In the present work, we examined the consumption of permethrin 5% cream in the four provinces of Galicia (a Spanish autonomous community) and described the seasonal variability and the annual evolution of its consumption between 2018 and 2021. A descriptive, cross-sectional, and retrospective study of the consumption of this drug, expressed in defined daily dose per 1000 inhabitants per day (DID), was carried out. The results obtained revealed differences between the amounts consumed in the four Galician provinces (p < 0.001). No specific geographical pattern was observed; however, the results suggested a marked seasonality and a slightly increasing global trend in the consumption of permethrin 5% cream throughout the study period. Since the only authorized indication of this drug in the study area is the treatment of scabies, this work may give an idea of the epidemiological situation of the disease in Galicia and serve to establish public health strategies against this parasitosis.

Piperazine derivatives with potent drug moiety as efficient acetylcholinesterase, butyrylcholinesterase, and glutathione S-transferase inhibitors

Cholinesterases catalyze the breakdown of the neurotransmitter acetylcholine (ACh), a naturally occurring neurotransmitter, into choline and acetic acid, allowing the nervous system to function properly. In the human body, cholinesterases come in two types, including acetylcholinesterase (AChE; E.C.3.1.1.7) and butyrylcholinesterase (BChE; E.C.3.1.1.8). Both cholinergic enzyme inhibitors are essential in the biochemical processes of the human body, notably in the brain. On the other hand, GSTs are found all across nature and are the principal Phase II detoxifying enzymes in eukaryotes and prokaryotes. Specific isozymes are identified as therapeutic targets because they are overexpressed in various malignancies and may have a role in the genesis of other diseases such as neurological disorders, multiple sclerosis, asthma, and especially cancer cell. Piperazine chemicals have a role in many biological processes and have fascinating pharmacological properties. As a result, therapeutically effective piperazine research is becoming more prominent. Half maximal inhibition concentrations (IC₅₀ ) of piperazine derivatives were found in ranging of 4.59-6.48 µM for AChE, 4.85-8.35 µM for BChE, and 3.94-8.66 µM for GST. Also, piperazine derivatives exhibited Ki values of 8.04 ± 5.73-61.94 ± 54.56, 0.24 ± 0.03-32.14 ± 16.20, and 7.73 ± 1.13-22.97 ± 9.10 µM toward AChE, BChE, and GST, respectively. Consequently, the inhibitory properties of the AChE/BChE and GST enzymes have been compared to Tacrine (for AChE and BChE) and Etacrynic acid (for GST).

Facilitations in the Clinical Diagnosis of Human Scabies through the Use of Ultraviolet Light (UV-Scab Scanning): A Case-Series Study

BACKGROUND

To confirm the suspicion of scabies, dermatologists have one pathognomonic sign, "the tunnel" through which Sarcoptes scabiei digs into the epidermis. Light microscopy is considered the most reliable procedure, but it is time-consuming and operator-dependent. Recently, dermoscopy has greatly improved the chances of recognizing mite in situ, but it is still linked to the examiner's experience and to the magnification capability of the device used.

METHODS

This article, based on a case-series study, describes a novel diagnostic path, which uses an ultraviolet LED source at 365 nm and a digital camera for the evaluation of lesions that raise the suspicion of scabies.

RESULTS

The gallery emits a naked-eye-visible wavy bluish-white linear luminescence, better than that of any standard lighting. UVA light is also able to identify Sarcoptes scabiei as a white or green point-shaped area. This sign can only be appreciated by enlarging its picture to full frame on a common PC monitor.

CONCLUSIONS

Ultraviolet light (365 nm) seems to offer help in the diagnosis of scabies because it saves time compared with light microscopy and because it does not require contact with the patient's skin, as in dermoscopy. Although examiner experience remains an important factor, it is easily compensated by procedural simplicity, the cost of the devices and, especially, by the clarity of the results, even in non-specific lesions.

Comparison of sulfur ointment and permethrin treatments in scabies

Scabies is a contagious, parasitic skin disease that adversely affects the quality of life and, can cause systemic complications if it is not properly treated. Sulfur ointment and permethrin cream are among the most used topical agents in the treatment of scabies. In this study, we aimed to compare the efficacy of sulfur ointment and permethrin cream in the treatment of scabies. In this single-center study, patients who were diagnosed with scabies in the dermatology outpatient clinics of Karabuk University Training and Research Hospital between April, 2021 and September, 2021 were investigated retrospectively. Age, gender, date of diagnosis, topical agent used for scabies treatment, and response to the treatment at the control examination in the second week were recorded. The patients were divided into two groups those receiving 5% permethrin cream or 10% sulfur ointment, and the treatment efficacy of both agents was compared. This study showed that 10% sulfur ointment was significantly more effective in treating scabies than 5% permethrin cream (p < 0.001). Moreover, younger patients with scabies responded better to both treatments. 10% Sulfur ointment can be considered a safe and effective topical option in the treatment of scabies. The resistance to 5% permethrin cream, which is the most commonly used agent for scabies, can be a concern as an unexpected low success rate was obtained in this study.

Increased Scabies Incidence at the Beginning of the 21st Century: What Do Reports from Europe and the World Show?

Reports from various countries have described increasing numbers of scabies cases, especially in the past two decades. The epidemiological data for various world regions showed prevalence estimates ranging from 0.2% to 71%, with the highest prevalence in the Pacific region and Latin America. Therefore, geographically, scabies occurs more commonly in the developing world, tropical climates, and in areas with a lack of access to water. According to results from specific regions of the world, the greatest burdens from scabies were recorded for East Asia, Southeast Asia, Oceania, tropical Latin America, and South Asia. Among countries with the highest rates, the top 10 were Indonesia, China, Timor-Leste, Vanuatu, Fiji, Cambodia, Laos, Myanmar, Vietnam, and the Seychelles. From Europe, available data shows an increasing trend in scabies infestation, particularly evident among populations with associated contributing factors, such as those who travel frequently, refugees, asylum seekers, those who regularly lack drinking water and appropriate hygiene and are of a younger age, etc. This increase in observed cases in the last 10–20 years has been evidenced by research conducted in Germany, France, Norway, and Croatia, among other countries. In addition, increased scabies transmission was also recorded during the COVID-19 pandemic and may have been the result of increased sexual intercourse during that time. Despite all the available treatment options, scabies commonly goes unrecognized and is therefore not treated accordingly. This trend calls for a prompt and synergistic reaction from all healthcare professionals, governmental institutions, and non-governmental organizations, especially in settings where population migration is common and where living standards are low. Furthermore, the proper education of whole populations and accessible healthcare are cornerstones of outbreak prevention. Accurate national data and proper disease reporting should be a goal for every country worldwide when developing strategic plans for preventing and controlling the community spread of scabies.

Comparison of in vitro Killing Effect of N, N-Diethyl-Meta-Toluamide (DEET) versus Permethrin on Demodex folliculorum

Background

There is no single effective treatment for demodicosis; successful treatment requires a multimodal approach. Relapse or recurrence of demodicosis is relatively high, making the therapy challenging. Several reports have documented the successful treatment of demodicosis with acaricidal agents, which aimed at reducing the excessive number of Demodex mites and improving the patients' symptoms. Reports of irritation and resistance to topical acaricidal agents have led to the search for effective alternative treatments.

Materials and Methods

A total of 100 standardized skin surface biopsy (SSSB) biopsy slides from 100 patients with demodicosis were randomly divided into five groups, each with 20 slides exposed to immersion oil, N, N-diethyl-meta-toluamide (DEET) 5%, 10%, 20%, and permethrin 1%, respectively. The microscopic evaluation started immediately after the test agents exposed the mites. The survival time (ST) was defined as the interval between the first exposure of Demodex folliculorum to the test agents to the time the movements ceased.

Results

The differences between the median ST of DEET 5% (44 min), 10% (22 min), and 20% (14 min) were significant when compared to the negative control group (240 min) with p<0.001, <0.001, <0.001, respectively. While the median ST of permethrin 1% (42 min) was not significantly different from the median ST of DEET 5% (p=0.7395).

Conclusion

This study demonstrated the dose-related acaricidal effect of DEET on D. folliculorum. The survival times of DEET 5%, 10%, and 20% were significantly shorter than the negative control (immersion oil). DEET 5% had a comparable in vitro killing effect as permethrin 1%. Further in vivo studies are necessary to determine the clinical efficacy in patients with demodicosis.

Spinosad topical suspension (0.9%): a new topical treatment for scabies

INTRODUCTION

Scabies is a highly contagious skin disease caused by the parasitic mite Sarcoptes scabiei. There is no vaccine and for the past 30 years, the first line treatments have been topical permethrin and oral ivermectin. These drugs target mainly the parasite nervous system, killing only the motile stages. As they lack ovicidal activities, repeat treatments are required to achieve complete cure. Incompliance to repeat treatments causing prolonged drug usage, has contributed to emerging drug resistances. In addition, they are not appropriate for all patient categories, specifically for infants and young children or pregnant and breast feeding women. Consequently, new single dose scabicides are urgently needed.

AREAS COVERED

In 2021, spinosad, a drug previously used to treat head lice, was approved by the US FDA as a topical scabies treatment. Here the pharmacology, clinical efficacy and tolerability of this drug are discussed.

EXPERT OPINION

As the first single dose scabicide the formulated 0.9% topical Spinosad solution shows significant efficacy, little systemic absorption and no serious adverse reactions, making it a promising treatment for classical scabies in patients older than four years.

Crusted Scabies, a Neglected Tropical Disease: Case Series and Literature Review

Crusted scabies is a rare form of scabies that presents with more severe symptoms than those of classic scabies. It is characterized by large crusted lesions, extensive scales, thick hyperkeratosis, and contains a large number of highly contagious itch mites. Crusted scabies is more prevalent in immunocompromised, malnourished, and disabled individuals. This disease has been linked to a variety of health problems, including delayed diagnosis, infection risk, and high mortality, mainly from sepsis, and it has the potential to cause an outbreak due to its hyper-infestation, which makes it highly infectious. This article reports three cases of crusted scabies in North Sulawesi, Indonesia. Recent updates and a comprehensive review of the literature on the disease are also included, emphasizing the critical importance of early diagnosis and effective medical management of patients, which are necessary to prevent the complications and spread in communities.

Comparison of Permethrin-Based Treatment Strategies against Scabies in Infants and Young Children

OBJECTIVE

To optimize the permethrin-based therapies for scabies infestations in infants and young children, the efficacies of 3 different regimens were evaluated.

STUDY DESIGN

The retrospective analysis encompassed 85 infants and children aged <4 years with scabies. The children had received either topical permethrin 5% on the entire body on days 1/8, on days 1/8/15, on days 1/8/15 plus interim applications restricted to hands and feet on days 2/3/4//9/10/11, or alternative treatments.

RESULTS

The intensified regimen, consisting of full-body permethrin applied on days 1/8/15 and hands/feet on days 2/3/4//9/10/11, resulted in cure of scabies in 73.5% of the cases. The cure rates were significantly greater compared with full-body permethrin given on days 1/8, which led to eradication in 44%, and were greater compared with the clearance in children who had received full-body permethrin on days 1/8/15 (53.8%) or alternative treatments (60%). For patients in whom permethrin had previously been applied, the intensified regimen resulted in eradication of scabies in 71.4% of the cases, compared with 30% and 55.6% after full-body permethrin on days 1/8 and 1/8/15, respectively.

CONCLUSIONS

The intensified regimen of full-body permethrin plus interim applications on hands/feet, which aims at reducing the number of mites present on the frequently heavily infested palmoplantar sites in addition to the standard entire body application, appears efficacious in curing scabies in young children.

Bullous Scabies in an Immunocompromised Host

A 40-year-old woman with a history of poorly controlled HIV presented to a district referral hospital in rural Botswana for a generalized skin rash of several months duration. The highly pruritic rash predominantly involved her hands and feet and was associated with bullae that were present for days at a time before rupturing without drainage or discharge. The patient endorsed night sweats, periodic fevers, occasional cough productive of blood-tinged sputum, fatigue, and weight loss. On admission, CD4 count was 46 cells/mm³ and viral load was >750000 copies/mL. Pulmonary tuberculosis testing via sputum was negative twice. A blood count demonstrated eosinophilia. Oral acyclovir was started empirically for disseminated herpes virus infection, with topical beclomethasone and intravenous antibiotics for possible superinfected bullous dermatosis. With inadequate response to treatment, a skin biopsy was obtained and microscopic examination demonstrated scabies mites. The absence of skin burrows, the presence of bullae, and working in a low-resource setting without direct access to microscopic examination delayed diagnosis. The patient was initiated on topical permethrin. Oral ivermectin was not available in country and was obtained from overseas shipment, delaying treatment initiation. Drastic improvement was seen after the patient initiated ivermectin. A local nurse in the patient's village visited her community and found multiple individuals with active scabies infection. The patient's discharge was delayed until these community members were treated successfully with topical permethrin. This case describes an atypical presentation of scabies in an under-resourced setting, demonstrating unique diagnostic, therapeutic, and public health challenges.

Spinosad at 0.9% in the treatment of scabies: Efficacy results from 2 multicenter, randomized, double-blind, vehicle-controlled studies

BACKGROUND

Scabies is a contagious skin disease resulting from Sarcoptes scabiei infestation. There are no approved over-the-counter treatments, and approved prescription products have disadvantages, including potential resistance. Spinosad, an insecticide derived from fermentation of a soil actinobacterium, shows promise as a potential treatment agent.

OBJECTIVE

Combined results from 2 controlled clinical studies were used to evaluate the efficacy of 0.9% spinosad topical suspension in the eradication of scabies.

METHODS

Each study included index subjects (the youngest household members with active scabies) and up to 5 other members in each household. Subjects applied 0.9% spinosad or vehicle once. Primary efficacy was the percentage of index subjects with complete cure on day 28. Additional efficacy included clinical cure, microscopic cure, and lesion counts.

RESULTS

Spinosad at 0.9% is not equivalent to vehicle in the percentage of index subjects achieving complete cure on day 28 (78.1% vs 39.6%, respectively; P < .0001; n = 206). Additional efficacy analyses confirmed the consistent treatment effect of 0.9% spinosad. No safety signals were observed.

LIMITATIONS

The studies used small sample sizes to assess equivalency.

CONCLUSIONS

Spinosad at 0.9% performed better than vehicle in the treatment of scabies in these studies of subjects of 4 years of age or older following 1 application of study drug.

Reemergence of Scabies Driven by Adolescents and Young Adults, Germany, 2009-2018

To validate anecdotal evidence on scabies infestations, we analyzed inpatient and outpatient claims data in Germany. Scabies diagnoses increased 9-fold and treatment failure 4-fold during 2009–2018, driven mainly by persons 15–24 years of age. Prevention and control in young adults appear key because of these persons’ high mobility and social connectivity.

[Development of an ivermectin-containing syrup as an extemporaneous preparation for treatment of scabies in children]

BACKGROUND

Oral ivermectin can be used to treat scabies. Evidence for safe and effective use in young children in individual treatment situations has been developed and published. In order to also ensure a body weight-adapted dosage for children, an ivermectin-containing syrup was developed as an extemporaneous preparation.

MATERIALS AND METHODS

Since ivermectin is not available as a pure substance for the formulation, tablets containing active ingredient were used as a basic material for development. The formulation was designed according to pharmaceutical, regulatory and use-oriented criteria. An HPLC (high-pressure liquid chromatography) method was developed and validated to demonstrate chemical stability. In order to facilitate the practical implementation, information on suitable packaging material and application aids was also developed and the formulation was evaluated.

RESULTS

It has been demonstrated that the final formulation produced in the pharmacy was stable and can be stored for 3 weeks. No concerns were raised regarding the tolerability of the syrup formulation. The physicochemical properties and the taste of the formulation allow the intended use as a well-dosed syrup for children.

CONCLUSION

The developed formulation meets the requirements of the Apothekenbetriebsordnung (Pharmacy Work Rules; Section 7 ApBetrO) and enables an exact, body weight-adapted dosage of oral ivermectin in young children. Studies on human pharmacokinetics or clinical studies to demonstrate tolerability and/or efficacy are not available for the formulation.

Eleven Danish patients diagnosed with Scabies and treated with Tenutex®

Treatment with Tenutex® should be considered in patients diagnosed with scabies if the first-line treatment with 5% permethrin fails. Treatment failure with 5% permethrin may be due to tolerance or resistance in scabies mites.

[Parasitoses in childhood]

Parasitoses are a frequent occurrence in pediatric consultations in both hospitals and private practices. Responsible for this are parasites that permanently infest human skin, such as Sarcoptes scabiei hominis and Pediculus humanus capitis (persistent parasites) as well as those that only attack the skin for feeding, such as Pulex irritans, Cimex lectularius und Neotrombicula autumnalis (transient parasites). The main symptom of parasitoses is pruritus, which is caused by a delayed allergic reaction to proteins in the saliva of the parasites. In some parasitoses, such as scabies, the pruritus is typical, occurs particularly at night and is associated with a considerable impairment in the quality of life due to the resulting lack of sleep, whereas the pruritus is often absent in the case of pediculosis capitis. In this article persistent and transient parasitoses are characterized based on the patient history, morphology and symptoms.

[Scabies-Renaissance of an ectoparasite infection : Diagnosis and therapy-How to proceed in practice]

Scabies or mange is currently a common dermatosis in Germany and other countries, and should be more important in health policy. It affects a cross-section of society, including all age groups, from infants to the aged. Locals and people with a migration background both suffer from this highly contagious ectoparasite infection with excessive, predominately nocturnal itching. Clinical diagnosis represents a challenge for the experienced dermatologist due to the variety of dermatosis to be considered in the differential diagnosis. It is still unclear whether treatment failure or the recurrences observed everywhere are due to in vitro and in vivo resistance of the pathogen agent Sarcoptes scabiei against permethrin or ivermectin. Therapeutic errors seem to play a role as often not all direct contact persons are recorded and treated with antiscabious treatment. They form the reservoir for reinfections. In the event of repeated nonresponse to topical (permethrin) and/or oral antiscabious treatment, alternative topical preparations-benzyl benzoate or crotamiton-should be used. Combination with ivermectin is mandatory.

Molecular drug targets for scabies: a medicinal chemistry perspective

Sarcoptes scabiei is a causative organism for scabies that affects an estimated global population of 300 million and remains a disease of significant concern. Recently, a number of potential drug targets were identified for scabies, including hydrolytic enzymes, inactivated paralogues of hydrolytic enzymes, inhibitors of host proteolytic enzymes and other proteins of interest. These discoveries remain confined to academic laboratories and institutions, failing to attract interest from researchers in commercial drug development. Here, we summarize the latest developments in the scabies mite biology and the drug targets that were subsequently identified, and we propose several peptide and nonpeptide ligands targeting the hot spots for protein-protein interactions. We also identify gaps in the development of ligands as inhibitors or modulators of these macromolecules.

A forgotten parasitic infestation in an immunocompromised patient-a case report of crusted scabies

Crusted scabies is a rare and highly contagious form of Sarcoptes scabiei var hominis infestation whose incidence may increase in the near future due to increasing use of immunosuppressive therapies and a general lack of awareness about the condition. It is misdiagnosed as psoriasis, irritant dermatitis or eczema. Delays in diagnosis lead to widespread transmission amongst contacts leading to potential community outbreak. Crusted scabies is extremely difficult to treat and there are growing concerns of possible resistance to current treatment. This case report describes a 44-year-old Ghanaian woman with human immunodeficiency virus (HIV) infection and diagnosed with skin scrapings. Treatment was initiated but the patient died from HIV related complications. Crusted scabies, though rare, should be an issue of global concern due to the potential for widespread dissemination. Adequate resources need to be channeled into scabies eradication as well as education of health personnel to promptly identify and treat cases.

Scabies: A comprehensive review and current perspectives

Human scabies is a contagious skin infestation caused by the parasitic mite Sarcoptes scabiei var. hominis. It is a common skin disease worldwide that occurs not only in the underprivileged sections of society but also in developed countries. In 2009, World Health Organization (WHO) recognized scabies as "neglected tropical disease (NTD)" or NTD thus emphasizing the need for community awareness and proper treatment strategies. This review attempts to summarize the varied clinical presentation of the disease and describes the advances in diagnosis and management including the ongoing search for novel agents to overcome the problems associated with conventional treatments. The literature research includes peer-reviewed articles (clinical trials or scientific reviews). Studies were identified by searching electronic databases (MEDLINE and PubMed) till February 2020 and reference lists of respective articles. Only articles published in English language were included.

Application errors associated with topical treatment of scabies: an observational study

BACKGROUND

In recent years, there has been a significant increase in scabies infestations throughout German-speaking countries. Given the high frequency of treatment failures, the question arises as to whether topical permethrin treatment is always performed correctly.

PATIENTS AND METHODS

Our department uses a fluorescent test cream to teach patients on how to correctly apply topical permethrin. In the context of a prospective observational study of 21 patients, we systematically assessed and analyzed potential application errors.

RESULTS

None of the participants succeeded in adequately applying the cream to the entire skin as previously instructed. The median number of regions left untreated was six (minimum: 2; maximum: 18), which included a median body surface area of 6 % (minimum: 2 %; maximum: 30 %). With regard to predilection sites of scabies, the ankles were left untreated in 62 % of cases, followed by the interdigital spaces (toes) (33 %) and the sacral region (24 %). All patients considered the pretreatment training to be very useful.

CONCLUSIONS

The present findings clearly demonstrate potential shortcomings when it comes to the application of topical antiscabies treatment. This may provide a (potentially underestimated) explanation for the large number of reports on treatment failures in this regard, which falsely suggest potential treatment resistance.

In vitro survival of scabies mites

BACKGROUND

The correct treatment and management of scabies is expensive and time-consuming, and may have a negative impact on patients and their families.

AIM

To investigate the effects of permethrin 5% cream on scabies mites, and explore mite survival times outside the human body.

METHODS

We performed a nonrandomized controlled study. In total, 20 petri dishes were coated with permethrin 5% cream (treatment group) and 20 plain petri dishes (control group) each had one scabies mite placed in them, and were then observed at baseline and 3, 4, 5, 6, 7, 8 and 12 h from baseline. In the second part of our study, 30 scabies mites from infested patients were investigated in an observational experiment in 30 plain petri dishes at days 0, 3 and 4.

RESULTS

Our data showed that 65% of scabies mites survived after 8 h in the treatment group compared with 75% of mites in the control group. After 12 h, 25% of mites in the treatment group and 60% in the control group were still alive. Data from the observational survival study showed that one mite was alive on day 3, but all mites were dead by day 4.

CONCLUSIONS

This study showed no significant effects of mite survival times with 5% topical permethrin after 8 h, while its efficacy was stronger and significant after 12 h. We recommend the isolation of all mite-infested items for at least 4 days.

The public health control of scabies: priorities for research and action

Scabies is a parasitic disease of the skin that disproportionately affects disadvantaged populations. The disease causes considerable morbidity and leads to severe bacterial infection and immune-mediated disease. Scientific advances from the past 5 years suggest that scabies is amenable to population-level control, particularly through mass drug administration. In recognition of these issues, WHO added scabies to the list of neglected tropical diseases in 2017. To develop a global control programme, key operational research questions must now be addressed. Standardised approaches to diagnosis and methods for mapping are required to further understand the burden of disease. The safety of treatments for young children, including with ivermectin and moxidectin, should be investigated. Studies are needed to inform optimum implementation of mass treatment, including the threshold for intervention, target, dosing, and frequency. Frameworks for surveillance, monitoring, and evaluation of control strategies are also necessary.

Digital PCR: a new technology for diagnosis of parasitic infections

BACKGROUND

Parasitic infections are responsible for a significant burden of disease worldwide as a result of international travel and immigration. More accurate diagnostic tools are necessary in support to parasite control and elimination programmes in endemic regions as well as for rapid case detection in non-endemic areas. Digital PCR (dPCR) is a powerful technology with recent applications in parasitology.

AIMS

This review provides for the first time an overview of dPCR as a novel technology applied to detection of parasitic infections, and highlights the most relevant potential benefits of this assay.

SOURCES

Peer-reviewed literature pertinent to this review based on PubMed, Cochrane and Embase databases as well as laboratory experience of authors.

CONTENT

Among the 86 studies retrieved, 17 used the dPCR applied to parasites belonging to protozoa (8), helminths (8) and arthropods (1) of clinical human interest. dPCR was adopted in four studies, respectively, for Plasmodium and Schistosoma japonicum. dPCR led to clear advantages over quantitative real-time PCR in P. falciparum and spp., and in S. japonicum showing higher sensitivity; and in Cryptosporidium with higher stability to inhibitors from stool. For all parasites, dPCR allows absolute quantitation without the need of a standard curve. Various dPCR platforms were used. A few critical factors need consideration: DNA load, choice of platform and reaction optimization.

IMPLICATIONS

Owing to its sensitivity and quantitative characteristics, dPCR is a potential candidate to become an appealing new method among the molecular technologies for parasite detection and quantitative analysis in the future. In general, it has more applications than genomic DNA detection only, such as quantitation in mixed infections, gene expression and mutation analysis. dPCR should be considered in malaria screening and diagnosis as a complement to routine assays and in schistosomiasis elimination programmes. Standardized strategies and further studies are needed for the integration of dPCR in routine clinical laboratory.

Infected with Scabies Again? Focus in Management in Long-Term Care Facilities

Scabies is a significant public health condition in long-term care facilities, plaguing even developed countries. Although treatments are available, eradication and control of scabies cases still remain a challenge due to delays in diagnosis and difficulties in maintaining preventive and surveillance measures. Prompt treatment of patients and their contacts that are affected, along with concomitant education of health staff and family members, are paramount. Environmental disinfestation is also a concern.

Increase of scabies in Germany and development of resistant mites? Evidence and consequences

Scabies has been diagnosed surprisingly frequently in Germany in recent years, and the use of acaricides has risen markedly. Present figures indicate an increase in the prevalence/incidence of scabies, but do not prove or quantify it for the following reasons: (a) scabies is not a notifiable disease in Germany; (b) the diagnosis is not always confirmed lege artis by means of light microscopy or dermatoscopy (which may lead to a comparatively high proportion of false‐positive diagnoses due to the low overall prevalence of scabies); (c) repeated treatments of the same patient and treatment of contact persons are included in the total number of prescriptions. Therefore, there are no valid data on disease occurrence, either in the current situation or from previous periods. Observations of ineffective treatment with permethrin have led to speculations that Sarcoptes mites are developing resistance to this drug. However, there is little evidence for this assumption. We discuss risk groups (children, elderly people in need of care, migrant health personnel in nursing institutions, refugees, sexually active young adults) and evaluate their possible contribution, albeit in the absence of evidence. None of the groups would be solely responsible for an increased frequency. We have compiled recommendations on how the management of scabies could be improved, and present a way of differentiating permethrin resistance from application errors and/or lack of compliance. The goal is to solve the epidemiological and parasitological questions mentioned above.

Tackling scabies: novel agents for a neglected disease

The scabies mite, Sarcoptes scabiei var hominis, is an obligate ectoparasite of humans. It has been a source of distress for humanity since antiquity. The troublesome mite is emerging triumphant over current acaricidal agents with reports of emerging resistance and treatment failures. Scabies in endemic areas and crusted scabies offer additional management challenges. Exploration of indigenous plants and better understanding of mite biology and pathogenesis provide opportunities for the development of novel agents for this common pest. We review the recent diverse approaches to scabies, including the use of novel plant products with a better safety profile, translating the use of moxidectin from veterinary practice to human scabies, vaccination, immunotherapy, and development of drugs that directly target mite molecules.

Control Strategies for Scabies

Scabies is a neglected tropical disease of the skin, causing severe itching and stigmatizing skin lesions. Further, scabies leads to impetigo, severe bacterial infections, and post-infectious complications. Around 200 million people are affected, particularly among disadvantaged populations living in crowded conditions in tropical areas. After almost 50 years, research into scabies control has shown great promise, particularly in highly-endemic island settings, but these findings have not been widely adopted. Newer approaches, utilizing ivermectin-based mass drug administration, appear feasible and highly effective. Inclusion of scabies in the WHO portfolio of neglected tropical diseases in 2017 may facilitate renewed opportunities and momentum toward global control. However, further operational research is needed to develop evidence-based strategies for control in a range of settings, and monitor their impact. Several enabling factors are required for successful implementation, including availability of affordable drug supply. Integration with existing health programs may provide a cost-effective approach to control.