A comparative trial of three treatment schedules for the eradication 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.

Prevalence of Scabies and Impetigo 3 Years After Mass Drug Administration With Ivermectin and Azithromycin

Background

Ivermectin-based mass drug administration has emerged as a promising strategy for the control of scabies and impetigo in settings where the diseases are endemic. Current follow-up data are limited to 12 months for the majority of studies. Longer-term data are vital to inform the sustainability of interventions.

Methods

We conducted a prevalence survey for scabies and impetigo in 10 villages in Choiseul Province of the Solomon Islands 36 months after a single round of ivermectin and azithromycin mass drug coadministration. In the primary analysis, we compared the prevalence of scabies and impetigo at 36 months to the prevalence at baseline.

Results

At 36 months, the prevalence of scabies was 4.7% (95% confidence interval [CI], 3.6–6.1), which was significantly lower than at baseline (18.7%; relative reduction, 74.9%; 95% CI, 61.5%–87.7%; P < .001). The prevalence of impetigo was 9.6% (95% CI, 8.1%–11.4%), significantly lower than at baseline (24.7%; relative reduction, 61.3%; 95% CI, 38.7%–100%; P < .001). The highest prevalence of scabies was among children aged <5 years (12.5%; adjusted odds ratio, 33.2; 95% CI, 6.6–603.2), and the highest prevalence of impetigo was among children aged 5–9 years (16.4%; adjusted odds ratio, 8.1; 95% CI, 3.6–21.8).

Conclusions

There was a sustained impact of a single round of ivermectin and azithromycin mass drug coadministration on the prevalence of scabies and impetigo 3 years after the intervention. Our data provide further support to adopt this intervention as a central component of global scabies control efforts.

Clinical Trials Registration

Australian and New Zealand Trials Registry (ACTRN12615001199505).

Scabies and impetigo in Samoa: A school-based clinical and molecular epidemiological study

Background

Common infections of the skin such as impetigo and scabies represent a large burden of disease globally, being particularly prevalent in tropical and resource-limited settings. Efforts to address these infections through mass drug administrations have recently been shown as efficacious and safe. In Samoa, a Pacific Island nation, there is a marked lack of epidemiological data for these neglected tropical diseases, or appreciation of their drivers in this setting.

Methods

An observational, cross-sectional survey of children aged between 4 and 15 years attending primary schools in rural areas of Upolu Island, Samoa was carried out to assess the prevalence of impetigo and scabies in schoolchildren residing in rural Samoa, integrated with descriptive epidemiological and microbial genomic data. A phylogenetic assessment of local Staphylococcus aureus isolated from Samoan schoolchildren was performed to estimate putative community transmission.

Findings

In this survey, the prevalence of impetigo observed in Samoan schoolchildren was one of the highest described globally (57•1%, 95% CI [53•8-60•5%], 476/833). Associations between active impetigo and age and gender were noted, with younger children and males more commonly affected (aOR2•8 [1•8-4•7]and aOR1•8 [1•3-2•5], respectively). The prevalence of scabies was similar to that seen in other South Pacific island countries (14•4%, 95% CI [12•2-17•0%], 120/833). Transmission of S. aureus was predicted, primarily between those children attending the same school. Carriage of S. pyogenes was notably low, with pharyngeal carriage observed in less than 2% of schoolchildren, consistent with earlier studies from Samoa.

Interpretation

This study describes a considerable burden of disease attributed to impetigo and scabies in Samoa. These findings will be valuable in addressing the public health challenge posed by these conditions, providing baseline prevalence data and highlighting practical strategies to reduce transmission of relevant microbes and parasites in this setting.

Tala Tomua

O a'afiaga o le pa'u i fa'ama'i o le po'u (impetigo) ma le utu o le pa'u (scabies), ua tele naua le fanau ua maua ai i le pasefika, ma le lalolagi atoa. O fuafuaga vaai mamao ma polokalame e fofoina ai nei faafitauli, e aofia ai le inumaga o fualaau e tapeina ai nei fa'ama'i, ua aliali mai ai e mafai ona faatamaia nei fa'ama'i. E le o tele ni tusitusiga ma faamaumauga i totonu o Samoa, pe ta'atele nei fa'amai o le pa'u pe leai. Ona o le le faatauaina o nei fa'ama'i, e le o iloa fo'i ni mafuaga ma nisi tulaga e faateleina ai nei fa'ama'i o le pa'u i Samoa.

Faatinoina o le suesuega

O le suesuega faasaenisi i le fanau aoga i le va o le 4 ma le 15 tausaga o loo ao'oga i le tulaga lua i nisi o nu'u i tua i Upolu, na faatinoina ai suesuega lea, ia suesueina ai le aotelega ma fainumera o le fanau ua maua i fa'ama'I o le po'u (impetigo) ma le utu o le pa'u (scabies). O lenei foi suesuega, na fia iloa ai fo'i po'o a ituaiga siama eseese o loo maua i luga o pa'u ma tino o le fanau aoga, ina ia iloa ai foi auala ua pipisi ai nei siama mai le isi tamaitiiti i le isi, ona mafua ai lea o nei fa'ama'i o le pa'u.

Tanuuga o le suesuega

Ua faailoa mai i le suesuega, le ta'atele o le fa'ama'i o le po'u (impetigo) ua maua ai le fanau aoga (57%), i aoga na faia ai le suesuega. O se fainumera ua maualuga tele i le lalolagi atoa. E toatele atu nisi o le fanau laiti (younger) ma tama (male) e maua i le po'u nai lo isi tamaiti. O le fainumera o le utu o le pa'u (scabies) (14·4%) e tai tutusa lava ma isi motu o le Pasefika. O le feaveaina o le siama faapitoa (staph aureus) ua tupu lea i le fanau ua ao'oga i le aoga e tasi. E le toatele foi nisi o le fanau (2%) na maua i le siama faapitoa o le fa'ai (strep pyogenes) e ona mafua ai le fiva rumatika. O lenei fainumera ua tai tutusa ma suesuega faasaenisi na fai muamua i Samoa.

Aotelega

O le aotelega la o lenei suesuega faasaenisi, ua faailoaina mai ai le tele naua o le fa'ama'i o le pa'u, o po'u (impetigo) ma le utu o le pa'u (scabies) i Samoa nei. O nei foi suesuega o le a aoga tele ini polokalame ma ni fuafuaga mamao e fa'afoisia ai nei faafitauli i le soifua maloloina o le fanau i Samoa. O le a avea foi nei fainumera e faamaumauina mo le silafia e le atunuu ma le soifua maloloina, le ta'atele o nei fa'amai o le pa'u, mo le tapenaina o ni fofo talafeagai ise taimi o i luma, ina ia faaitiitina ai le pipisi o nei siami i fanau ao'oga i Samoa.

Therapeutic potential of medicinal plants for the management of scabies

Sarcoptes scabiei (S. scabiei), a parasite mite which causes scabies disease resulting in serious public health concern. The long-term scabies disease can lead to complications such as septicemia, acute post-streptococcal glomerulonephritis, heart disease, and secondary infections. Timely treatment to the affected patients is required to control the disease and get rid of the causative agent. Delayed diagnosis and inappropriate treatment can lead to serious consequences. The most common treatment strategy is the use of allopathic medicines which can immediately relieve the patient but have the drawback of side effects. The safe and cost-effective alternative treatment strategy is the use of medicinal plants which have beneficial therapeutic potential against variety of diseases due to the presence of many bioactive phytoconstituents with no or minimal side effects. For the present review, the published articles describing scabies disease and its phytotherapeutic modalities were searched through different data bases including Google Scholar, PubMed, Medline, and ScienceDirect using the keywords like S. scabiei, prevalence of scabies disease, and phytotherapy of scabies. A large number of medicinal plants, such as Melaleuca alternifolia, Curcuma longa, Azadirachta indica, Rosmarinus officinalis, Capsicum annuum, Cinnamomum camphor, Solanum nigrum, and Eupatorium perfoliatum, have been reviewed for the promising future treatments of scabies. All the studied plants have many bioactive compounds with potential therapeutic effects against scabies and can be utilized for therapeutic purposes for this disease. This literature study has limitations because of the lack of sufficient data due to limited pre-clinical trials in this particular area. This review provides a baseline to explore the therapeutic potential of these medicinal plants against skin diseases. However, extensive studies are required to identify, authenticate, and characterize the bioactive compounds present in these plants which may lead to value addition in pharmaceutical industries providing the cost-effective way of treatment with minimal side effects.

Interventions for preventing the spread of infestation in close contacts of people with scabies

BACKGROUND

Scabies, caused by Sarcoptes scabiei variety hominis or the human itch mite, is a common parasitic infection. While anyone can become infected, it causes significant morbidity in immunocompromised hosts and it spreads easily between human hosts where there is overcrowding or poor sanitation. The most common symptom reported is itch which is worse at night. As the symptoms are attributed to an allergic reaction to the mite, symptoms usually develop between four to six weeks after primary infection. Therefore, people may be infected for some time prior to developing symptoms. During this time, while asymptomatic, they may spread infection to others they are in close contact with. Consequently, it is usually recommended that when an index case is being treated, others who have been in close contact with the index case should also be provided with treatment.

OBJECTIVES

To assess the effects of prophylactic interventions for contacts of people with scabies to prevent infestation in the contacts.

SEARCH METHODS

We searched electronic databases (Cochrane Occupational Safety and Health Review Group Specialised Register, CENTRAL (The Cochrane Library), MEDLINE (Ovid), Pubmed, EMBASE, LILACS, CINAHL, OpenGrey and WHO ICTRP) up to November 2013.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or cluster RCTs which compared prophylactic interventions which were given to contacts of index cases with scabies infestation. Interventions could be compared to each other, or to placebo or to no treatment. Both drug treatments and non-drug treatments were acceptable.

DATA COLLECTION AND ANALYSIS

Two authors intended to extract dichotomous data (developed infection or did not develop infection) for the effects of interventions and report this as risk ratios with 95% confidence intervals. We intended to report any adverse outcomes similarly.

MAIN RESULTS

We did not include any trials in this review. Out of 29 potentially-relevant studies, we excluded 16 RCTs as the data for the contacts were either not reported or were reported only in combination with the outcomes for the index cases. We excluded a further 11 studies as they were not RCTs. We also excluded one study as not all subjects were examined at baseline and follow-up, and another as it was a case study.

AUTHORS' CONCLUSIONS

The effects of providing prophylactic treatments for contacts of people with scabies to prevent infestation are unknown. We need well-designed RCTs of the use of prophylactic measures to prevent the transmission of scabies conducted with people who had the opportunity for prolonged skin contact with an index case, such as family members, healthcare workers or residential care personnel, within the previous six weeks.

Scabies: a review of diagnosis and management based on mite biology

Scabies is a contagious parasitic dermatitis that is a significant cause of morbidity, especially outside of the United States. Scabies is diagnosed most often by correlating clinical suspicion with the identification of a burrow. Although scabies should be on the differential for any patient who presents with a pruritic dermatosis, clinicians must consider a wide range of diagnostic possibilities. This approach will help make scabies simultaneously less over- and underdiagnosed by clinicians in the community. Atypical or otherwise complex presentations may necessitate the use of more definitive diagnostic modalities, such as microscopic examination of KOH prepared skin scrapings, high-resolution digital photography, dermoscopy, or biopsy. Scabies therapy involves making the correct diagnosis, recognizing the correct clinical context to guide treatment of contacts and fomites, choosing the most effective medication, understanding how to use the agent properly, and following a rational basis for when to use and reuse that agent. Although the development of new therapeutic agents is always welcome, tried and true treatments are still effective today. Permethrin is the gold standard therapy, with malathion being an excellent topical alternative. Ivermectin is an effective oral alternative that is especially useful in crusted scabies, patients who are bed ridden, and in institutional outbreaks. Despite the availability of effective therapeutics, treatment failures still occur, mostly secondary to application error (ie, failure to treat the face and scalp or close contacts, failure to reapply medication) or failure to decontaminate fomites. Because increasing resistance to scabies treatments may be on the horizon, we propose that standard of care for scabies treatment should involve routine treatment of the scalp and face and re-treating patients at day 4 on the basis of the scabies life cycle to ensure more efficient mite eradication. Practitioners should attempt to treat all close contacts simultaneously with the source patient. To eradicate mites, all fomites should be placed in a dryer for 10 minutes on a high setting, furniture and carpets vacuumed, and nonlaunderables isolated for a minimum of 2 days, or, for those who wish to be rigorous, 3 weeks.

Scabies and pyodermas--diagnosis and treatment

Scabies and pyodermas are two of the commonest skin infections in tropical settings. They affect large numbers of people, particularly children, and account for a large burden of disease for peripheral health care teams. Despite this there have been significant advances in our knowledge of these diseases, their impact and their management. However there is a need to evaluate these developments in this specific setting, tropical health and in the context of communities with limited resources. This section will describe these advances and the challenges that remain.

Disease burden and health-care clinic attendances for young children in remote aboriginal communities of northern Australia

OBJECTIVE

To determine the frequency of presentations and infectious-disease burden at primary health care (PHC) services in young children in two remote Aboriginal communities in tropical northern Australia.

METHODS

Children born after 1 January 2001, who were resident at 30 September 2005 and for whom consent was obtained, were studied. Clinic records were reviewed for all presentations between 1 January 2002 and 30 September 2005. Data collected included reason for presentation (if infectious), antibiotic prescription and referral to hospital.

FINDINGS

There were 7273 clinic presentations for 174 children aged 0-4.75 years, 55% of whom were male. The median presentation rate per child per year was 16 (23 in the first year of life). Upper-respiratory-tract infections (32%) and skin infections (18%) were the most common infectious reasons for presentation. First presentations for scabies and skin sores peaked at the age of 2 months. By 1 year of age, 63% and 69% of children had presented with scabies and skin sores, respectively.

CONCLUSION

These Aboriginal children average about two visits per month to PHC centres during their first year of life. This high rate is testament to the disease burden, the willingness of Aboriginal people to use health services and the high workload experienced by these health services. Scabies and skin sores remain significant health problems, with this study describing a previously undocumented burden of these conditions commencing within the first few months of life. Appropriate prevention and treatment strategies should encompass early infancy to reduce the high burden of infectious diseases in this population.

Interventions for treating scabies

BACKGROUND

Scabies is an intensely itchy parasitic infection of the skin caused by the Sarcoptes scabiei mite. It is a common public health problem with an estimated global prevalence of 300 million cases. Serious adverse effects have been reported for some drugs used to treat scabies.

OBJECTIVES

To evaluate topical and systemic drugs for treating scabies.

SEARCH STRATEGY

In February 2007, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2006, Issue 1), MEDLINE, EMBASE, LILACS, and INDMED. In March 2007, we also searched the grey literature and sources for registered trials. We also checked the reference lists of retrieved studies.

SELECTION CRITERIA

Randomized controlled trials of drug treatments for scabies.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Results were presented as relative risks with 95% confidence intervals and data combined where appropriate.

MAIN RESULTS

Twenty small trials involving 2392 people were included. One trial was placebo controlled, 16 compared two or more drug treatments, two compared treatment regimens, and one compared different drug vehicles.Fewer treatment failures occurred by day seven with oral ivermectin in one small trial (55 participants). Topical permethrin appeared more effective than oral ivermectin (85 participants, 1 trial), topical crotamiton (194 participants, 2 trials), and topical lindane (753 participants, 5 trials). Permethrin also appeared more effective in reducing itch persistence than either crotamiton (94 participants, 1 trial) or lindane (490 participants, 2 trials). One small trial did not detect a difference between permethrin (a synthetic pyrethroid) and a natural pyrethrin-based topical treatment (40 participants). No significant difference was detected in the number of treatment failures between crotamiton and lindane (100 participants, 1 trial), lindane and sulfur (68 participants, 1 trial), benzyl benzoate and sulfur (158 participants, 1 trial), and benzyl benzoate and natural synergized pyrethrins (240 participants, 1 trial); all were topical treatments. No trials of malathion were identified. No serious adverse events were reported. A number of trials reported skin reactions in participants randomized to topical treatments. There were occasional reports of headache, abdominal pain, diarrhoea, vomiting, and hypotension.

AUTHORS' CONCLUSIONS

Topical permethrin appears to be the most effective treatment for scabies. Ivermectin appears to be an effective oral treatment. More research is needed on the effectiveness of malathion, particularly when compared to permethrin, and on the management of scabies in an institutional setting and at a community level.

Therapy for head lice based on life cycle, resistance, and safety considerations

The timing of head lice maturation most favorable to their survival in the presence of anti-lice agents is the maximum time as an ovum (12 days) and the shortest possible time of maturing from newly hatched nymph to egg-laying adult (8.5 days). Pediculicides that are not reliably ovicidal (pyrethroids and lindane) require 2 to 3 treatment cycles to eradicate lice. Ovicidal therapies (malathion) require 1 to 2 treatments. Treatment with an agent to which there is genetic resistance is unproductive. In the United States, lice have become increasingly resistant to pyrethroids and lindane but not to malathion. Treatment with malathion has favorable efficacy and safety profiles and enables the immediate, safe return to school. Nit combing can be performed adjunctively. No-nit policies should be rendered obsolete.

Problems in diagnosing scabies, a global disease in human and animal populations

Scabies is a worldwide disease and a major public health problem in many developing countries, related primarily to poverty and overcrowding. In remote Aboriginal communities in northern Australia, prevalences of up to 50% among children have been described, despite the availability of effective chemotherapy. Sarcoptic mange is also an important veterinary disease engendering significant morbidity and mortality in wild, domestic, and farmed animals. Scabies is caused by the ectoparasitic mite Sarcoptes scabiei burrowing into the host epidermis. Clinical symptoms include intensely itchy lesions that often are a precursor to secondary bacterial pyoderma, septicemia, and, in humans, poststreptococcal glomerulonephritis. Although diagnosed scabies cases can be successfully treated, the rash of the primary infestation takes 4 to 6 weeks to develop, and thus, transmission to others often occurs prior to therapy. In humans, the symptoms of scabies infestations can mimic other dermatological skin diseases, and traditional tests to diagnose scabies are less than 50% accurate. To aid early identification of disease and thus treatment, a simple, cheap, sensitive, and specific test for routine diagnosis of active scabies is essential. Recent developments leading to the expression and purification of S. scabiei recombinant antigens have identified a number of molecules with diagnostic potential, and current studies include the investigation and assessment of the accuracy of these recombinant proteins in identifying antibodies in individuals with active scabies and in differentiating those with past exposure. Early identification of disease will enable selective treatment of those affected, reduce transmission and the requirement for mass treatment, limit the potential for escalating mite resistance, and provide another means of controlling scabies in populations in areas of endemicity.

Itch and scratch: scabies and pediculosis

Scabies and lice infestations are almost an everyday diagnosis in the dermatology clinics. Along with the unbearable itch, resistance to medication, secondary infection, and the high risk for spreading the parasite to their close contacts, the patients have also to battle with many myths, prejudice, and shames connected to those infestations.

Lindane neurotoxicity in childhood

Lindane (gamma-benzene-hexachloride) has been widely used as an antiscabetic and a pediculicidal agent for the past 50 years with reasonably good efficacy. After its initial use as a first-line therapy, there have been several reports of its neurotoxicity, especially among infants and young children. Literature review reveals that the risk of its neurotoxicity is minimal if used properly and strictly according to the prescribed recommendations. However, following availability of other safer and equally efficacious alternatives, it is now being regarded as a second-line therapy for scabies and pediculosis.

Ectoparasitic sexually transmitted diseases: Scabies and pediculosis

Scabies and pediculosis are diagnosed on an almost daily basis in many dermatology offices. Whether the patient seeks medical attention because of the often unbearable itch of scabies or because of the fear of lice infestations, the physician should be on the lookout for these ectoparasitic infestations. Secondary bacterial infection, resistance to medication, and the risk of spread of the infestations to family members and other close contacts may complicate the problem. Patients frequently have to battle the myths, prejudices, and even shame that are associated with such infestations.

Scabies: more than just an irritation

Human scabies, caused by skin infestation with the arthropod mite, Sarcoptes scabiei, typically results in a papular, intensely pruritic eruption involving the interdigital spaces, and flexure creases. Recent research has led to a reassessment of the morbidity attributable to this parasite in endemic communities, particularly resulting from secondary skin sepsis and postinfective complications including glomerulonephritis. This has led to studies of the benefits of community based control programmes, and to concerns regarding the emergence of drug resistance when such strategies are employed. The renewed research interest into the biology of this infection has resulted in the application of molecular tools. This has established that canine and human scabies populations are genetically distinct, a finding with major implications for the formulation of public health control policies. Further research is needed to increase understanding of drug resistance, and to identify new drug targets and potential vaccine candidates.

Reversible neurotoxicity after an overdose of topical lindane in an infant

Lindane (gamma benzene hexachloride) is a widely prescribed topical scabicide because of its efficacy and cost-effectiveness. Although toxicity from a single proper application of lindane is generally not observed, the hazards of repeated applications, industrial exposure, and accidental ingestion have been well documented. We herein describe an infant with reversible neurotoxicity following repeated applications of 1% lindane for the treatment of scabies. The role of factors predisposing to increased absorption and the recommendations to minimize potential neurotoxicity are emphasized.

First documentation of in vivo and in vitro ivermectin resistance in Sarcoptes scabiei

Ivermectin is increasingly being used to treat scabies, especially crusted (Norwegian) scabies. However, treatment failures, recrudescence, and reinfection can occur, even after multiple doses. Ivermectin resistance has been documented for some intestinal helminths in animals with intensive ivermectin exposure. Ivermectin resistance has also been induced in arthropods in laboratory experiments but, to date, has not been documented among arthropods in nature. We report clinical and in vitro evidence of ivermectin resistance in 2 patients with multiple recurrences of crusted scabies who had previously received 30 and 58 doses of ivermectin over 4 and 4.5 years, respectively. As predicted, ivermectin resistance in scabies mites can develop after intensive ivermectin use.

Scabies: New Future for a Neglected Disease

Scabies is a disease of global proportions in both human and animal populations, resulting from infestation of the skin with the "itch" mite Sarcoptes scabiei. Despite the availability of effective chemotherapy the intensely itching lesions engender significant morbidity primarily due to secondary sepsis and post-infective complications. Some patients experience an extreme form of the disease, crusted scabies, in which many hundreds of mites may infest the skin causin severe crusting and hyperkeratosis. Overcrowded living conditions and poverty have been identified as significant confounding factors in transmission of the mite in humans. Control is hindered by difficulties with diagnosis, the cost of treatment, evidence for emerging resistance and lack of effective vaccines. Historically research on scabies has been extremely limited because of the difficulty in obtaining sufficient quantities of the organism. Recent molecular approaches have enabled considerable advances in the study of population genetics and transmission dynamics of S. scabiei. However, the most exciting and promising development is the potential exploitation of newly available data from S. scabiei cDNA libraries and EST projects. Ultimately this knowledge may aid early identification of disease, novel forms of chemotherapy, vaccine development and new treatment possibilities for this important but neglected parasite.

Pharmacotherapy of ectoparasitic infections

Epizoonoses such as scabies, lice and cimicosis are common, vexing disorders that occur worldwide. Historically, many treatment modalities have been employed in the management of these disorders, and most of the drugs described in this review are of historical interest and no longer recommended or in widespread use because of their wide spectrum of adverse effects. More recently, reports documenting resistance against various antiectoparasite drugs, complicated and severe courses of the diseases, and adverse effects of drug therapy have prompted the development of new treatment strategies and drugs for optimal disease management. Because the strategies currently recommended for the treatment of ectoparasites differ worldwide, this review proposes a rational approach to selecting the best therapeutic agent by comparing the pharmacokinetics, pharmacodynamics, drug efficacy and adverse effects. A literature search of the currently Internet accessible libraries PubMed, Medline and Ideal library, of citations of articles found there, and from communications with the Federal Institute for Drugs and Medical Devices, Germany, was conducted based on this approach. One major observation of this literature search is that permethrin is the treatment of choice for lice and scabies in the US and in Great Britain, whereas lindane is still recommended for scabies in most other European countries because of its longer-standing record of effectiveness. Although permethrin has not yet been proven to be more effective than lindane in treating infections with these ectoparasites, it currently appears to have the best efficacy versus safety profile of topical treatments for scabies and lice. Ivermectin is a newer oral drug for the treatment of ectoparasites, which has been used with great success in the treatment of onchocercosis and other endoparasites. Although ivermectin appears to be a promising drug, its role in the treatment of ectoparasitic infections will be clarified as more study data become available. Finally, it is important to emphasise the clinical aspects of ectoparasite therapy and that providing the patient with optimal instructions on the use of topical therapeutics is of great importance in avoiding adverse effects and assuring complete removal of the ectoparasite, thereby avoiding the development of drug-resistance.

The use of ivermectin in controlling an outbreak of scabies in a prison

BACKGROUND

Ivermectin is a potentially useful treatment for scabies.

OBJECTIVES

We aimed to evaluate the efficacy of ivermectin in the treatment of scabies in an institutional environment.

METHODS

A single dose of ivermectin 150 microg kg-1 was given under supervision to 1153 prisoners in a prison in northern Tanzania where there was an outbreak of scabies.

RESULTS

Thirty per cent of the prisoners were cured after 1 week, 88% after 4 weeks and 95.5% after 8 weeks. Of 16 prisoners with crusted scabies, seven (44%) still had scabies after 8 weeks. Those who were not cured were then treated with 1% lindane lotion topically, as were the prison staff who had scabies. This regimen eradicated scabies from the prison for the next 2 years.

CONCLUSIONS

Ivermectin is an effective and safe treatment for scabies, particularly in a closed community, such as a prison, where it is easy to administer and avoids problems with compliance. It was of limited efficiency in crusted scabies as a single dose and we recommend that for such patients oral ivermectin is used in combination with a topical scabicide.

Management of endemic outbreaks of scabies with allethrin, permethrin, and ivermectin

BACKGROUND

At three residences for the elderly, recurrent scabies infestations became out of control. Due to the failure of repeated, nonsynchronized therapeutic efforts with conventional external anti-scabies treatments, an eradication program had to be developed. We describe a protocol for the management of outbreaks of scabies.

METHODS

According to the clinical examination and microscopically identified mites, all individuals of the population (IOP: patients, staff, and family members) were divided into two groups: (a) healthy and infested IOP; and (b) cases with crusted scabies. The first group was treated simultaneously once with external scabicides (allethrin or permethrin). All others were hospitalized and treated either with systemic ivermectin or with the latter in combination with permethrin.

RESULTS

In 252 IOP living in three residences for the elderly, clinical signs of scabies were reported in 91.5%, 78.5%, and 15.4% of the patients (age 55-97 years; mean, 80.5 years), 54.1%, 32.9%, and 16.6% of staff members, and in 7%, 3%, and 0% of family members. The infested IOP showed crusted scabies (index cases) in 5.3%, 5.0%, and 1.7%, common scabies in 43.1%, 36.7%, and 7.1%, and postscabiotic dermatitis in 10.3%, 7.6%, and 3.5%. In 99.2% of the synchronously treated IOP in group (a) (n = 240), the conventional treatment with permethrin cream 5% or allethrin spray was effective. Group (b) (n=12) received ivermectin (12 mg) once (n=5) or twice (n= 7) after an interval of 8 days. One index case received permethrin three times.

CONCLUSIONS

Outbreaks of scabies in populations of elderly people require special management for disease control. Synchronous treatment with external permethrin cream 5% or allethrin spray, including all IOP once, and close control offers a time-saving, cheap, and reliable method. Crusted scabies should be treated by oral administration of ivermectin once or twice after an interval of 8 days. Additional applications of permethrin and mechanical clearing of hyperkeratotic subungual areas shorten the course.

Studies in vitro on the relative efficacy of current acaricides for Sarcoptes scabiei var. hominis

Resistance of Sarcoptes scabiei to various topical therapies has been described, but clinical assessment of treatment failure is problematic and in-vitro assays are generally not available. We describe a simple in-vitro analysis used to evaluate the relative efficacy of a range of topical, oral, and herbal treatments available in Australia for the treatment of scabies. S. scabiei var. hominis mites were collected from skin scrapings obtained from 7 crusted scabies patients over a period of 2 years (1997 and 1998). Larvae, nymphal instars, and adult mites were tested within 3 h of collection and continuously exposed to selected commercially available treatment products until death, with the elapsed time recorded. Neem was the only product to show little acaricidal activity. Survival curves indicated that, of the other agents, 5% permethrin (Lyclear) had the slowest killing time, with 35% of mites still alive after 3 h, and 4% still alive after 18-22 h of constant exposure. In contrast, no mites were alive after 3 h exposure to 25% benzyl benzoate (Ascabiol), 1% lindane (Quellada), 5% tea tree oil and 100-8000 ng/g of ivermectin (Equimec). Despite the slower killing time with 5% permethrin, there was no evidence of any mite tolerance in vivo or treatment failure in any patients or contact cases.

Interventions for treating scabies

BACKGROUND

Scabies is a common public health problem with an estimated prevalence of 300 million. Infestation can cause considerable discomfort and intense itching. Severe adverse effects have been reported for some drugs used to treat scabies.

OBJECTIVES

The objective of this review is to assess the effects and toxicity of topical and systemic drug treatment for scabies.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group trials register, the Cochrane Controlled Trials Register, Medline, Embase, military records, traditional medicine databases. We also contacted international specialist centres and drug manufacturers.

SELECTION CRITERIA

Randomised controlled trials of any drug treatment for scabies. Tolerability and toxicity were sought in any study of humans taking any drug treatments for scabies.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed trial quality and extracted data.

MAIN RESULTS

Eleven trials were included (7 compared drug treatments, 2 compared treatment regimes, 1 compared the drug vehicle and 1 was a community intervention). Compared with placebo in one small trial, ivermectin was associated with a significant higher clinical cure rate at seven days. Permethrin appeared to be more effective than crotamiton for clinical and parasitic cure rates. Permethrin appeared to be better than gamma benzene hexachloride for clinical cure rates in two small trials but had no advantage in the largest trial (test for heterogeneity p< 0.001). Permethrin also appeared more effective in reducing itch persistance than gamma benzene hexachloride. There appeared to be no difference in clinical cure rates between crotamiton and gamma benzene hexachloride. Single trials assessed: the effectiveness of oral versus topical treatment (ivermectin versus benzyl benzoate); treatment vehicle (pork fat versus cold cream); and mass community treatment (ivermectin) but were too small to demonstrate an effect. No randomised trials of malathion were identified. Serious adverse drug reactions (including death and convulsions) have been reported in other studies of scabies drugs, most notably gamma benzene hexachoride and ivermectin.

REVIEWER'S CONCLUSIONS

The evidence that permethrin is more effective than gamma benzene hexachloride is inconsistent. Permethrin appears to have less potential serious drugs reactions than gamma benzene hexachloride although this is not derived from trial data. More research is needed of the safety and effectiveness of ivermectin and malathion compared to permethrin, on community management, and on different regimes and vehicles for topical treatment.

Success of a scabies control program in an Australian aboriginal community

OBJECTIVE

To adapt, implement and evaluate a model of scabies control in an Australian Aboriginal community.

METHODS

After initially examining the population, we offered all residents treatment with 5% permethrin cream. Visits were made during the ensuing 25 months to rescreen and to treat new-cases of scabies and contacts.

RESULTS

The prevalence of scabies was reduced from 28.8% before the program to < 10% during the entire period (from 32.3% to < 10% in children) (P < 0.01 for each visit). The initial prevalence of pyoderma in children was 69.4%, which was reduced and maintained at approximately one-half that rate during the last 16 months (P < 0.004 for the last 4 visits). Residual pyoderma in children was significantly less severe and no longer scabies-related.

CONCLUSIONS

This simplified model of scabies control had a substantial effect on scabies prevalence and on pyoderma prevalence and severity which was sustained for > 2 years. It could prove useful for other communities with high rates of scabies and pyoderma.

A risk-benefit assessment of agents used in the treatment of scabies

Permethrin is probably the most effective topical treatment for scabies. There is little microbial resistance to the drug, and it is highly effective. Toxicity is limited to occasional contact dermatitis. Similarly, oral ivermectin 200 micrograms/kg is extremely effective. Oral administration eliminates the need to be certain that medication has been applied properly. Toxicity has been very limited. It is not available in the US for human use in scabies at this time. The toxicity of most of other treatments that are available has not been studied carefully. Sulphur 6% in petrolatum is recommended as safe, but there are no good studies to confirm this. Sulphur is probably the medication of choice when cost is the overriding concern. Crotamiton and benzyl benzoate are probably safe, but are not as effective as permethrin. Lindane has some potential CNS toxicity if used incorrectly, and must be used carefully on damaged skin to avoid excessive absorption. It is important to stress that all household and sexual contacts must be treated, whether or not they have symptoms. Proper application of topical medications must be achieved, including under the fingernails, and up to the edge of all body orifices.

Treatment of scabies in rural east Africa--a comparative study of two regimens

Scabies is endemic in Africa where living conditions make synchronous treatment of every member of the large extended family impossible. An open study was designed to investigate the optimum treatment of school children in rural Tanzania. In one school where 34 children (7%) were infested, treatment with benzyl benzoate was distributed to the affected child and those sleeping in close proximity. In another school where 29 pupils (6.4%) were affected, the above treatment was given along with soap and some scabicidal ointment (6% sulphur) to be used on residually affected areas. Again, the treatment was given to those sleeping in proximity. One month later 46% were clear at the first school and a significantly higher proportion (69%) at the second. I conclude that inefficient application of scabicidal treatment and lack of washing contribute to scabies treatment failures. Synchronous treatment of small groups within the extended family can be effective.

Community control of scabies: a model based on use of permethrin cream

For 18 years treatment with lindane or crotamiton products has failed to stem the epidemic of scabies among the Kuna Indians in the San Blas islands of the Republic of Panama. Permethrin 5% cream was introduced as the only treatment in a programme to control scabies on an island of 756 inhabitants and involving workers recruited locally. Prevalence fell from 33% to less than 1% after every person was treated. As long as continued surveillance and treatment of newly introduced cases was maintained, prevalence of scabies remained below 1.5% for over 3 years. When supply of medication was interrupted for 3 weeks, prevalence rose to 3.6%. When control was lost after the US invasion of Panama, prevalence rose to 12% within 3 months. Bacterial skin infections decreased dramatically when scabies was controlled. Permethrin is safe and effective even in areas where this disease has become resistant to lindane.

Scabies in nursing homes: an eradication program with permethrin 5% cream

Permethrin 5% cream was used to treat scabies in three large nursing homes under a compassionate-plea protocol for chronic, therapy-resistant infestations. All residents, staff, and frequent visitors were treated whether or not symptomatic. Family members of these groups were treated either when symptomatic or directly exposed to scabies. Nine hundred ninety-five persons were treated, 202 of whom were diagnosed with scabies. Approximately 35% (111 of 313) of nursing home residents were diagnosed with scabies. These were patients in whom multiple treatments with other scabicides were unsuccessful. At the completion of the study, 195 patients were examined for efficacy of treatment. Of these, 91 (46.7%) had clearing of lesions with one medication application, 77 (39.5%) with two treatments, and 23 (11.8%) with three or more treatments. The overall cure rate was 98%. Adverse experiences occurred in 2.4% of cases and were mild (i.e., pruritus and rash).

Comparison of crotamiton 10% cream (Eurax) and permethrin 5% cream (Elimite) for the treatment of scabies in children

Permethrin 5% cream (Elimite) was approved as a treatment for scabies by the U.S. Food and Drug Administration in September 1989. In a double-blinded, randomized study, it was compared with crotamiton 10% cream (Eurax) for the treatment of scabies in children 2 months to 5 years of age. Two weeks after a single overnight treatment, 14 (30%) of 47 children were cured with permethrin 5% cream, in contrast to only 6 of 47 (13%) of subjects treated with Eurax. Four weeks after treatment the figures were 89% and 60% cured for the two agents, respectively. In 10 of the 19 patients whose treatment failed, the condition became worse after therapy. The difference in efficacy in favor of permethrin was significant (P = 0.002). That agent also demonstrated greater effectiveness in reducing pruritus and secondary bacterial infections. Elimite offers a safe, efficacious, and cosmetically elegant alternative to Eurax in the treatment of scabies in children.

Permethrin 5% dermal cream: a new treatment for scabies

Permethrin 5% dermal cream (Burroughs Wellcome Co.) was compared in an investigator-blinded, randomized study against lindane 1% lotion (Kwell) for the treatment of microscopically confirmed scabies. Eleven of twenty-three patients treated with permethrin cream were cured in 2 weeks (48%). Only two patients had scabies 1 month following a single treatment with this product, giving a cure rate of 91%. One of these two patients was considered to have a reinfestation. Only three of twenty-three (13%) patients treated with 1% lindane lotion (Kwell) were free of scabies 2 weeks after a single treatment and fifteen of twenty-three (65%) were cured at 1 month. The unusually high percentage of treatment failures (35%) following lindane therapy may have been related to extensive use of this agent for head lice and scabies in this village during the preceding 5 years. The higher cure rate at 1 month seen with permethrin cream was significant (p less than 0.025). Permethrin 5% dermal cream offers a new, cosmetically elegant alternative to lindane therapy and was effective in a community in which lindane demonstrated an unacceptable level of treatment failures.

Arthropod bites, stings, and infestations: their prevention and treatment

Readily available information as to the management of arthropod bites, stings, and infestations is important to have but often difficult to find. This article brings such information together in one reference for use by the practicing pediatrician, dermatologist, and family practitioner. Preventive measures are stressed and therapy is outlined for each entity; the rationale for many of the interventions is discussed. It is not the intent of this paper to cover each subject comprehensively.

Scabies and lice

Scabies and pediculosis, two commonly encountered infestations both having an incidence that is on the rise, are discussed in detail in this article with special emphasis given to their symptomatology, pathogenesis, and treatment.