The Treatment of Scabies

The Efficacy and Biopharmaceutical Properties of a Fixed-Dose Combination of Disulfiram and Benzyl Benzoate

Scabies and hair lice are parasitic diseases that affect human skin and hair, respectively. The incidence and resistances of these infections are increasing. Tenutex^® (disulfiram and benzyl benzoate emulsion) is an alternative to standard insecticides to avoid resistances. The aim of the work is to evaluate the transdermal absorption and the in vitro efficacy against scabies and hair lice after different exposition times. Dermatomed human skin was used to assess the dermal absorption using a validated High Performance Liquid Chromatography (HPLC) method. HEK001 keratinocytes were used to evaluate the cytotoxicity of benzyl benzoate. Only benzyl benzoate was able to cross the skin, but it did not show cytotoxicity at any of the tested concentrations. The product efficacy was tested on Psoroptes ovis after direct contact and after administration on sheep skin explants at different contact times. Permethrin/malathion-resistant strains of Pediculus humanis capitis adults and eggs were directly exposed to Tenutex, and the vitality and hatchability, respectively, were evaluated. The anti-scabies study demonstrated that exposure for 6 or 24 h completely eradicated the parasite. The pediculicidal activity of Tenutex exhibited superior efficacy than standard treatment on resistant lice. The positive results obtained suggest that Tenutex^® is a good treatment option, especially in drug resistance situations.

[Scabies-clinical resistance to permethrin therapy : Case reports and a critical discussion of current treatment recommendations]

Scabies is a contagious disease with increasing frequency. This is confirmed by data from insurance companies as well as increased search queries on Google. There is a controversial discussion in the scientific literature whether the mite has become resistant to standard therapy with permethrin. One case report and a group of cases (N = 12) from a mother-child facility are described in the following demonstrating decreased effectiveness of permethrin therapy. Dermatoscopy can be helpful in diagnosis and in assessing effectiveness of therapy. Dermatoscopic criteria are shown and therapeutic concepts are critically discussed.

Intervention protocol to improve scabies control in enclosed communities: a case report

OBJECTIVES

To describe patients with scabies in a prison setting. Document what type of treatment was carried out. Prepare an intervention protocol to improve scabies control in the Penitentiary Center.

MATERIAL AND METHOD

All cases of scabies diagnosed in the Youth Detention Centre (La Roca del Vallès, Barcelona) between November 2018 and November 2019 were recorded. The treatment used was recorded. Bibliographical research on the protocols and treatment guidelines was carried out for community-acquired scabies.

RESULTS

The study was performed with 762 inmates, of whom 61 patients were diagnosed with scabies. 39 patients' pathologies were detected at the time of admission to the center, 11 cases were diagnosed in the first 6 weeks after entering the prison, coinciding with the incubation period of the disease. Finally, 11 more were diagnosed when they had already been in prison for more than 6 weeks and therefore could be infected cases within the center. This parasitosis was detected mainly in inmates of North African origin, 14.7% of Algerian inmates and 14.2% of Moroccan inmates presented this pathology, compared to 1.6% among Spanish prisoners. All 61 patients were treated with permethrin and 8 cases had to repeat the treatment cycle due to apparent therapeutic failure. Research literature indicates that oral ivermectin should be the drug of first choice for the treatment of scabies in prison.

DISCUSSION

The high incidence of scabies cases detected in prison led us to carry out a bibliographic review that brought about changes in the treatment protocol that may be of interest for the control of the disease in closed communities.

[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.

A randomized controlled trial comparing the effectiveness of individual versus household treatment for Scabies in Lambaréné, Gabon

Background

It is unclear whether individual treatment of scabies is similarly effective compared to household treatment. This study compared these two treatment strategies with topical benzyl benzoate for treating scabies in Lambaréné, Gabon.

Methods

Participants presenting with uncomplicated scabies were randomized into either the Individual Treatment group, where only the affected participants received treatment, or the Household Treatment group, where all family members were treated in parallel to the affected participants regardless of signs and symptoms. The primary endpoint was clinical cure after 28 days; the secondary endpoint was the proportion of affected household members per household after 28 days.

Results

After 28 days, from a total of 79 participants assessed, 67% (n = 53) were clinically cured; 59% (20/34) in the Individual Treatment group and 73% (33/45) in the Household Treatment group. Participants in the Household Treatment group had about twice the odds of being cured (odds ratio 1.9, 95% confidence interval: 0.8–4.9; p = 0.17). For the secondary outcome, an effect of similar size was observed.

Conclusions

Our findings show that treating close contacts of persons affected by scabies may be beneficial to patients and contacts, however, the benefit was less pronounced than anticipated and further research is needed to definitively answer this question.

Scabies is a skin disease caused by parasitic mites that burrow into the skin and cause itchiness and rash. Since these mites can be easily transmitted from person to person the disease is highly contagious. Many guidelines on the treatment of scabies recommend that all family members and close contacts of persons suffering from scabies should be treated alongside the affected person, in order to prevent the disease from spreading. However, there is only little evidence to be found in the medical literature on how well this practice works. We conducted a study in Lambaréné, Gabon and surrounding villages, where many cases of scabies occurred at the time, to answer this question. We found that, on average, those patients whose entire family was treated were more likely to be cured after 4 weeks, and that fewer of their family members were affected. However, the difference to patients whose families weren’t treated was smaller than expected, suggesting that larger studies are needed to definitively answer the question.

An Antibody Persistent and Protective Two rSsCLP-Based Subunit Cocktail Vaccine against Sarcoptes scabiei in a Rabbit Model

Scabies is a highly contagious disease caused by Sarcoptes scabiei which burrows into stratum corneum of host's skin. In this study, after optimizing vaccination schedule, a vaccination trial is comprised of three test groups of rabbits (n = 10/group) by immunization with (1) rSsCLP5; (2) rSsCLP12; or (3) a mixture of rSsCLP5 and rSsCLP12, three biological replicates groups (n = 10/group) and three control groups (n = 10/group). Levels of specific IgG, total IgE and cytokines in sera were detected and histopathologically analyzed as indicators of vaccine effects. The results showed that 85% (17/20) of rabbits exhibited no detectable skin lesions of S. scabiei infestation in mixed protein groups compared to single protein groups with 75% (15/20) and 70% (14/20), respectively. Moreover, the deworming rates of mixed groups are increased by 10%-20% compared with that of single groups. Each of six groups immunized with rSsCLP displayed significant increases of specific IgG, total IgE, IL-10, and TNF-α. The degree of skin damage in test groups also significantly lower than that of control groups. Thus, purified rSsCLP5 and rSsCLP12 subunit cocktail vaccine induced robust immune protection and could significantly decrease mite populations to reduce the direct transmission between rabbits.

Clinical presentation and risk factors of increased scabies cases in the Western region of Saudi Arabia in 2016-2018

OBJECTIVES

To describe the clinical characteristics of scabies in the Makkah province and analyze risk factors associated with the outbreak.  Methods: A cross-sectional study was conducted between June 2016 and June 2018 by collecting the data of patients reported to have infestations at King Abdulaziz Medical City, Makkah, Saudi Arabia. A comparative analysis was conducted of patients reported before and during the outbreak of scabies.  Results: Of the 352 patients identified, the range of cases was 0-24 cases per month before the months of the outbreak (March to April 2018). However, the actual number of cases reported increased 2.8 times the expected maximum in April 2018. Saudi nationals were 2.5 times more affected than non-Saudi nationals during the outbreak period compared to before the outbreak (95%CI: 1.02, 6.05, p=0.045). Symptoms involving upper arms, axillae (53.7% versus 68.7%, p=0.048), and torso (50% versus 66.4%, p=0.033) were significantly under-represented among outbreak patients. The presence of additional comorbidities was reported more frequently in patients diagnosed with scabies before versus during the outbreak months (25.8% versus 8.2%, p=0.014). Permethrin prescriptions increased (75.6% versus 41%), crotamiton prescriptions decreased (13.5% versus 48%), and the hospitalization was lower (3.8% versus 13.5%) during the outbreak.  Conclusion: The clinical presentation and risk factors of scabies change significantly with scabies outbreaks, and consequently so do the lines of treatment in Saudi Arabia. The present study highlights the importance of adopting strategies related to community infection control and prevention.

[Scabies in old age]

Scabies is a frequent ectoparasitosis the prevalence of which also seems to increase in older patients. Correct and timely diagnosis of scabies in older age is hampered by atypical clinical manifestations, the potential lack of pruritus and a variety of differential diagnoses. Scabies crustosa, a highly contagious subtype due to the presence of innumerable mites, is of particular importance. It predominantly occurs in immunosuppressed patients as well as in mentally or physically disabled persons and is the most important source of scabies outbreaks in residential and nursing homes. This article reviews the diagnosis and treatment of scabies and the strategies for managing outbreaks with special reference to older patients.

Ivermectin and permethrin for treating scabies

BACKGROUND

Scabies is an intensely itchy parasitic infection of the skin. It occurs worldwide, but is particularly problematic in areas of poor sanitation, overcrowding, and social disruption. In recent years, permethrin and ivermectin have become the most relevant treatment options for scabies.

OBJECTIVES

To assess the efficacy and safety of topical permethrin and topical or systemic ivermectin for scabies in people of all ages.

SEARCH METHODS

We searched the following databases up to 25 April 2017: the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, and IndMED. We searched the World Health Organization International Clinical Trials Registry Platform, the ISRCTN registry, CenterWatch Clinical Trials Listing, ClinicalTrials.gov, TrialsCentral, and the UK Department of Health National Research Register for ongoing trials. We also searched multiple sources for grey literature and checked reference lists of included studies for additional trials.

SELECTION CRITERIA

We included randomized controlled trials that compared permethrin or ivermectin against each other for people with scabies of all ages and either sex.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the identified records, extracted data, and assessed the risk of bias for the included trials.The primary outcome was complete clearance of scabies. Secondary outcomes were number of participants re-treated, number of participants with at least one adverse event, and number of participants withdrawn from study due to an adverse event.We summarized dichotomous outcomes using risk ratios (RR) with 95% confidence intervals (CI). If it was not possible to calculate the point estimate, we described the data qualitatively. Where appropriate, we calculated combined effect estimates using a random-effects model and assessed heterogeneity. We calculated numbers needed to treat for an additional beneficial outcome when we found a difference.We assessed the certainty of the evidence using the GRADE approach. We used the control rate average to provide illustrative clearance rates in the comparison groups.

MAIN RESULTS

Fifteen studies (1896 participants) comparing topical permethrin, systemic ivermectin, or topical ivermectin met the inclusion criteria. Overall, the risk of bias in the included trials was moderate: reporting in many studies was poor. Nearly all studies were conducted in South Asia or North Africa, where the disease is more common, and is associated with poverty.EfficacyOral ivermectin (at a standard dose of 200 μg/kg) may lead to slightly lower rates of complete clearance after one week compared to permethrin 5% cream. Using the average clearance rate of 65% in the trials with permethrin, the illustrative clearance with ivermectin is 43% (RR 0.65, 95% CI 0.54 to 0.78; 613 participants, 6 studies; low-certainty evidence). However, by week two there may be little or no difference (illustrative clearance of permethrin 74% compared to ivermectin 68%; RR 0.91, 95% CI 0.76 to 1.08; 459 participants, 5 studies; low-certainty evidence). Treatments with one to three doses of ivermectin or one to three applications of permethrin may lead to little or no difference in rates of complete clearance after four weeks' follow-up (illustrative cures with 1 to 3 applications of permethrin 93% and with 1 to 3 doses of ivermectin 86%; RR 0.92, 95% CI 0.82 to 1.03; 581 participants, 5 studies; low-certainty evidence).After one week of treatment with oral ivermectin at a standard dose of 200 μg/kg or one application of permethrin 5% lotion, there is probably little or no difference in complete clearance rates (illustrative cure rates: permethrin 73%, ivermectin 68%; RR 0.93, 95% CI 0.74 to 1.17; 120 participants, 1 study; moderate-certainty evidence). After two weeks of treatment, one dose of systemic ivermectin compared to one application of permethrin lotion may lead to similar complete clearance rates (extrapolated cure rates: 67% in both groups; RR 1.00, 95% CI 0.78 to 1.29; 120 participants, 1 study; low-certainty evidence).There is probably little or no difference in rates of complete clearance between systemic ivermectin at standard dose and topical ivermectin 1% lotion four weeks after initiation of treatment (illustrative cure rates: oral ivermectin 97%, ivermectin lotion 96%; RR 0.99, 95% CI 0.95 to 1.03; 272 participants, 2 studies; moderate-certainty evidence). Likewise, after four weeks, ivermectin lotion probably leads to little or no difference in rates of complete clearance when compared to permethrin cream (extrapolated cure rates: permethrin cream 94%, ivermectin lotion 96%; RR 1.02, 95% CI 0.96 to 1.08; 210 participants, 1 study; moderate-certainty evidence), and there is little or no difference among systemic ivermectin in different doses (extrapolated cure rates: 2 doses 90%, 1 dose 87%; RR 0.97, 95% CI 0.83 to 1.14; 80 participants, 1 study; high-certainty evidence).SafetyReporting of adverse events in the included studies was suboptimal. No withdrawals due to adverse events occurred in either the systemic ivermectin or the permethrin group (moderate-certainty evidence). Two weeks after treatment initiation, there is probably little or no difference in the proportion of participants treated with systemic ivermectin or permethrin cream who experienced at least one adverse event (55 participants, 1 study; moderate-certainty evidence). After four weeks, ivermectin may lead to a slightly larger proportion of participants with at least one adverse event (extrapolated rates: permethrin 4%, ivermectin 5%; RR 1.30, 95% CI 0.35 to 4.83; 502 participants, 4 studies; low-certainty evidence).Adverse events in participants treated with topical ivermectin were rare and of mild intensity and comparable to those with systemic ivermectin. For this comparison, it is uncertain whether there is any difference in the number of participants with at least one adverse event (very low-certainty evidence). No withdrawals due to adverse events occurred (62 participants, 1 study; moderate-certainty evidence).It is uncertain whether topical ivermectin or permethrin differ in the number of participants with at least one adverse event (very low-certainty evidence). We found no studies comparing systemic ivermectin in different doses that assessed safety outcomes.

AUTHORS' CONCLUSIONS

We found that for the most part, there was no difference detected in the efficacy of permethrin compared to systemic or topical ivermectin. Overall, few and mild adverse events were reported. Our confidence in the effect estimates was mostly low to moderate. Poor reporting is a major limitation.