Risk factors for recurrence of scabies: a retrospective study of scabies patients in a long-term care hospital

Scabies in infants and children - a narrative review

Scabies is a human ectoparasitosis caused by Sarcoptes scabei var. hominis. World-wide around 300 million patients are affected. Infants and children have the highest incidence rates. Poverty and overcrowding are social factors contributing to a higher risk of transmission and treatment failure. The leading symptom of the infestation is itch. Complications are bacterial infections that are responsible for mortality. Diagnosis is clinical. Non-invasive imaging technologies like dermoscopy can be used. Polymerase chain reaction (PCR) is less sensitive and specific than microscopy of skin scrapings. Treatment of choice is topical permethrin 5%. Ivermectin is the only oral drug FDA-approved for scabies. It should be used in cases non-responsive to topical therapy and in case of high number of infested patients in addition to topical therapy. Pseudo-resistance to treatment is not uncommon. New drugs are on the horizon. What is Known: • Pruritus is the leading symptom causing sleep disturbances and scratching with the risk of secondary bacterial infections. • Treatment failure is related to inappropriate application of topical drugs and asymptomatic family members. What is New: • COVID-19 pandemic and migration are contributing to an increased incidence of scabies. • New compounds to treat scabies are on the horizon.

Severe Scabies: A French Multi-centre Study Involving 95 Patients with Crusted and Profuse Disease and Review of the Literature

The aim of this multi-centre French retrospective study was to identify severe, i.e. crusted and profuse, scabies patients. Records were retrieved from 22 Dermatology or Infectious Diseases departments in the Ile-de-France from January 2009 to January 2015 to characterize epidemiology, demography, diagnosis, contributing factors, treatment features, and outcomes in severe scabies. A total of 95 inpatients (57 crusted and 38 profuse) were included. A higher number of cases was observed among elderly patients (>75 years), mostly living in institutions. Thirteen patients (13.6%) reported a history of previously treated scabies. Sixty-three patients (66.3%) had been seen by a previous practitioner for the current episode (up to 8 previous visits). Initial misdiagnosis (e.g. eczema, prurigo, drug-related eruptions, psoriasis) was documented in 41 patients (43.1%). Fifty-eight patients (61%) had already received 1 or more previous treatments for their current episode. Forty percent received corticosteroids or acitretin for an initial diagnosis of eczema or psoriasis. Median time from the onset of symptoms to the diagnosis of severe scabies was 3 months (range 0.3-22). Itch was present in all patients at diagnosis. Most patients (n=84, 88.4%) had comorbidities. Diagnostic and therapeutic approaches varied. Complications occurred in 11.5% of cases. To date, there is no consensus for diagnosis and treatment, and future standardization of is required for optimal management.

MRSA Femoral Osteomyelitis from Superinfected Scabies Lesions: A Pediatric Case Report

Scabies is a skin infestation from the Sarcoptes scabiei. It is considered a public health issue causing concern in developing countries and is considered a “neglected tropical disease” by the World Health Organization (WHO). Scabies skin lesions may cause severe itching and can be the portal of entry for opportunistic and pathogenic bacteria, which can cause serious systemic infections. We report the case of a 3-year-old boy with recurrent scabies infections who presented to the emergency department because of a fever and refusal to walk. Blood tests showed neutrophilic leukocytosis and significantly increased C reactive protein (CRP) and procalcitonin. Upon medical examination, his right thigh was extremely painful upon palpation, knee flexion was lost and he was unable to stand, so magnetic resonance imaging (MRI) was performed. MRI showed osteomyelitis of metaphysis and distal diaphysis of the right femur with associated subperiosteal purulent collection and concomitant pyomyositis and fasciitis of the distal right thigh. Blood cultures were positive for methicillin-resistant Staphylococcus aureus (MRSA). The patient received a long course of intravenous antibiotic therapy and his condition slowly improved. Follow-up femur X-ray showed a mixed pattern of erosion and sclerosis at the meta-diaphyseal region and periosteal reaction at the diaphyseal region. This case highlights the importance of early scabies diagnosis even in Western countries where poverty and household overcrowding are uncommon. Early diagnosis, timely initiation of proper treatment and evidence of clinical resolution are important elements to prevent recurrence of infection and serious systemic superinfections even from multi-drug resistant bacteria. Clinical consequences from unrecognized disease or inadequate eradication are preventable.

Risk factors for scabies treatment resistance: a retrospective cohort study

BACKGROUND

In order to successfully treat scabies and to prevent its spread, it is important to identify the factors that can influence the outcome of scabies treatment.

OBJECTIVES

This study was designed to evaluate the risk factors associated with treatment resistance scabies during use of an effective topical medication.

METHODS

A retrospective cohort study was performed in patients with scabies infestations confirmed by potassium hydroxide (KOH) examinations. Patient characteristics, clinical features and treatment history were collected. The treatment resistance group included patients with persistent scabies infestations for more than 28 days after initiation of antiscabies treatment with 5% permethrin cream.

RESULTS

In total, 138 patients with scabies infestations treated between January 2017 and December 2020 were included in this study. Of these, 100 (72.5%) patients were treated successfully, while 38 (27.5%) patients experienced treatment resistance. In the univariable analysis, risk factors for treatment resistance scabies included impaired cognitive function (OR = 2.66, 95% CI, 1.15-6.14), limited mobility (OR = 2.97, 95% CI, 1.30-6.83), inpatient status (vs. outpatient, OR = 3.3, 95% CI, 1.28-8.54), topical steroid use before diagnosis (OR = 3.52, 95% CI, 1.61-7.81), systemic steroid use before diagnosis (OR = 3.57, 95% CI, 1.26-10.34) and a positive KOH exam after the first treatment (OR = 7.25, 95% CI, 3.24-17.11). In the multivariable analysis, limited mobility (OR = 3.46, 95% CI, 1.02-12.11) and topical steroid use before diagnosis (OR = 3.65, 95% CI, 1.41-9.75) were significant predictive factors for treatment resistance scabies.

CONCLUSIONS

Scabies patients with limited mobility and topical steroid use before diagnosis are at high risk of treatment resistance. Dermatologists should take these findings into consideration when treating patients with scabies infestations.

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.

Recurrence rate of scabies in patients 14 years or older in Saudi Arabia

Objectives:

To estimate the rate of scabies diagnostic recurrence and identify factors associated with the high likelihood of frequent scabies recurrences among adults in Saudi Arabia.

Methods:

This multi-center retrospective study was conducted in adult patients who were diagnosed with one or multiple recurrent infestations of scabies between January 2016 and September 2018 at the Ministry of National Guard-Health Affairs hospitals and clinics, Saudi Arabia. The number of scabies recurrences during the study period was recorded and modeled using a Poisson model.

Results:

A total of 468 adult patients (39.8±17.8, range: 14.2-105.7 years) were included in the study, resulting in 645 scabies diagnoses in which 302 (46.8%) were recurrences. The multivariate Poisson model revealed that male gender (adjusted rate ratios [aRR]: 1.465; 95%CI: 1.064 - 2.017; p=0.019), first tertile (January to April) (aRR: 3.021; 95%CI: 1.484 - 6.149; p=0.002), and high humidity (aRR: 1.066; 95%CI: 1.002 - 1.133; p=0.043) had a higher likelihood of frequent scabies recurrences.

Conclusion:

The rate of scabies recurrence among adult patients in Saudi Arabia was high, and is comparable with previous report in Japan. The study suggests that male gender, first tertile, and high humidity were independently associated with the high rate of scabies recurrences among adults. An interventional program to lower the rate of scabies recurrences and prevent outbreak should be undertaken.

Epidemiologic Trends and Seasonality of Scabies in South Korea, 2010-2017

Scabies is a parasitic skin infection with intense itching. Scabies infection seriously impairs quality of life, while outbreaks in medical institutions cause financial losses. This study aimed to present the annual and seasonal trend of prevalence of scabies in the national population. Scabies cases were extracted from National Health Insurance Service database and its epidemiologic characteristics were assessed. To analyze the seasonality of scabies occurrence, temperature and humidity were included in the model as weather factors, and the per capita gross national income index was adjusted. The annual prevalence by age group was 0.56-0.69 per 1,000 persons until the age of 40 years and peaked at 3.0-4.1 per 1,000 persons in the age group over 80 years. The number of women diagnosed with scabies has been consistently higher compared to that of men since 2010. Mean number of cases diagnosed as scabies was lowest in spring, approximately 4,000 cases, when the average temperature was less than 5°C at 2 months prior, whereas more than 6,000 scabies cases occurred in autumn when temperatures exceeded 25°C at 2 months prior. This study presents the epidemiological characteristics and seasonality of all cases nationwide over 8 years and will help to establish control policies.

Rate and factors for scabies recurrence in children in Saudi Arabia: a retrospective study

Background

Despite the fact that several scabies outbreaks emerged in schools in Saudi Arabia in 2018, no study has investigated the risk of scabies recurrence among children in Saudi Arabia. This study aimed to estimate the rate of scabies recurrence and identify factors that were associated with an increased risk of recurrence among children.

Methods

This is a multi-center retrospective study of children (age < 14 years) who were diagnosed between May 20, 2015 and September 12, 2018 with one or multiple recurrent scabies at the Ministry of National Guard Health Affairs (MNGHA) hospitals and clinics in Saudi Arabia. Data were obtained from an electronic health system, BestCare database.

Results

A sample of 264 children analyzed (mean age of 6.7 years) resulted in a cumulative number of 316 scabies diagnoses in which 86 (27.2%) experienced scabies recurrence (at least once). Independent factors associated with a high risk of scabies recurrence: older children (adjusted hazard ratio [aHR], 1.036; 95% CI, 1.002–1.072; P = 0.039), female gender (aHR, 1.734; 95% CI, 1.329–2.262; P = 0.001), Western region of Saudi Arabia (aHR, 1.548; 95% CI, 1.115–2.151; P = 0.009), and 2nd tertile season [May to August] (aHR, 2.368; 95% CI, 1.706–3.288; P = 0.001).

Conclusions

The study demonstrated that the recurrence rate of scabies among children is high. Older children, the female gender, the Western region of Saudi Arabia, and the seasonality were independently associated with an increased risk of scabies recurrence. High temperature and low humidity should be explored as leading factors for scabies infestations in Saudi Arabia. Findings derived from this study may be useful for clinicians and governments in optimizing clinical management of scabies cases and contacts.

Risk factors for treatment failure in scabies: a cohort study

BACKGROUND

Treatment failure, which occurs in about one-third of cases, is considered as a major factor in the increasing incidence of scabies in developed countries.

OBJECTIVES

To identify predictors of treatment failure of scabies in ambulatory populations.

METHODS

This multicentre study compared the clinical characteristics and treatment modalities between a group of patients with scabies treated successfully and another group who were not cured 3 months after antiscabies treatment.

RESULTS

In total 210 patients with a diagnosis of scabies were included, comprising 98 patients in the treatment success group and 112 in the treatment failure group. The main risk factors for treatment failure were (i) the use of only one type of treatment, topical benzyl benzoate (BB) or oral ivermectin, vs. the combination of both treatments [odds ratio (OR) 2·15, 95% confidence interval (CI) 1·22-3·77]; (ii) the use of a single intake (vs. two) of oral ivermectin (OR 10·2. 95% CI 4·49-23·2); (iii) intake of ivermectin during a meal vs. on an empty stomach (OR 4·31, 95% CI 1·89-9·84); (iv) absence of decontamination of furnishings (OR 8·72, 95% CI 3·50-21·8), in particular sofa and cushions (OR 5·90, 95% CI 2·34-14·9), mattresses (OR 4·16, 95% CI 1·35-12·8) or car seats (OR 6·57, 95% CI 3·27-13·2) and (v) absence of written documents explaining treatment modalities (OR 5·18, 95% CI 2·57-10·4). In multivariate analysis, treatment failure was mainly associated with (i) use of a single intake (vs. two) of ivermectin (OR 6·62, 95% CI 2·71-16·2); (ii) use of BB alone vs. two intakes of ivermectin (OR 3·51, 95% CI 1·55-7·95) and (iii) absence of decontamination of furniture with acaricides (OR 5·81, 95% CI 1·96-16·7).

CONCLUSIONS

Use of topical BB alone and a single intake (vs. two) of ivermectin are predictors of treatment failure.

Diagnosis, prevention, and treatment of scabies

Scabies remains a public health problem, especially in developing countries, with a worldwide incidence of approximately 300 million cases each year. Prolonged skin-to-skin contact is necessary to allow the transmission of the causative mite, Sarcoptes scabiei. Classic scabies presents with burrows, erythematous papules, and generalized pruritus. Clinical variants include nodular scabies and crusted scabies, also called Norwegian scabies. The diagnosis is based mainly on history and physical examination, but definitive diagnosis depends on direct visualization of the mites under microscopy. Alternative diagnostic methods include the burrow ink test, video-dermatoscopy, newly serologic tests like PCR/ELISA, and specific IgE directed toward major mite components. Treatment of scabies consists of either topical permethrin or oral ivermectin, although the optimal regimen is still unclear.