Risk factors of scabies in psychiatric and long-term care hospitals: A nationwide mail-in survey in Japan

Investigating the epidemiology and outbreaks of scabies in Japanese households, residential care facilities, and hospitals using claims data: the Longevity Improvement & Fair Evidence (LIFE) study

Objectives

This study aimed to characterize the epidemiology of scabies and its outbreaks in Japanese households, residential care facilities (RCFs), and hospitals using claims data.

Methods

This descriptive epidemiological study was conducted using claims data from eight municipalities in Japan. Scabies cases were identified using a combination of recorded diagnoses and administered medications. The study period was from April 2015 to March 2019. Outbreaks were defined as ≥2 cases of scabies occurring within a calendar month at a single household, RCF, or hospital.

Results

We identified 857 scabies cases for analysis. The annual prevalence of scabies ranged from 40 to 67 per 100,000 beneficiaries. The annual attack rate of scabies was found to be highest in RCFs (21 per 1000 RCFs), followed by hospitals (11 per 1000 hospitals) and households (0.25 per 1000 households). The annual outbreak attack rate was also highest in RCFs (4.0 per 1000 RCFs), followed by hospitals (1.6 per 1000 hospitals) and household (0.027 per household). The patterns of outbreaks varied widely among the RCFs.

Conclusions

The study showcases the potential of claims data for detecting infectious disease outbreaks, which could provide valuable insight for the future management and prevention of scabies. Infection control of scabies in RCFs is crucial in aging societies.

Risk factors for scabies in hospital: a systematic review

BACKGROUND

Annually, 175.4 million people are infected with scabies worldwide. Although parasitic infections are important nosocomial infections, they are unrecognized compared to bacterial, fungal, and viral infections. In particular, nonspecific cutaneous manifestations of scabies lead to delayed diagnosis and frequent nosocomial transmission. Hospital-based studies on the risk factors for scabies have yet to be systematically reviewed.

METHODS

The study followed the PRISMA guidelines and was prospectively registered in PROSPERO (CRD42023363278). Literature searches were conducted in three international (PubMed, Embase, and CINAHL) and four Korean (DBpia, KISS, RISS, and Science ON) databases. We included hospital-based studies with risk estimates calculated with 95% confidence intervals for risk factors for scabies infection. The quality of the studies was assessed using the Joanna Briggs Institute critical appraisal tools. Two authors independently performed the screening and assessed the quality of the studies.

RESULTS

A total of 12 studies were included. Personal characteristics were categorized into demographic, economic, residential, and behavioral factors. The identified risk factors were low economic status and unhygienic behavioral practices. Being a patient in a long-term care facility or institution was an important factor. Frequent patient contact and lack of personal protective equipment were identified as risk factors. For clinical characteristics, factors were categorized as personal health and hospital environment. People who had contact with itchy others were at higher risk of developing scabies. Patients with higher severity and those with a large number of catheters are also at increased risk for scabies infection.

CONCLUSIONS

Factors contributing to scabies in hospitals range from personal to clinical. We emphasize the importance of performing a full skin examination when patients present with scabies symptoms and are transferred from settings such as nursing homes and assisted-living facilities, to reduce the transmission of scabies. In addition, patient education to prevent scabies and infection control systems for healthcare workers, such as wearing personal protective equipment, are needed.

A Survey on Scabies Inpatients in South Korea Based on Health Insurance Claims Data from 2010 to 2019

Due to the growing aging population and the increased number of long-term patients staying in nursing facilities, the prevalence of scabies has recently been increasing, even in developed countries. This study aimed to identify the actual status of hospitalized patients with scabies in South Korea using the national health insurance claims data. From 2010 to 2019, 2586 patients were hospitalized with scabies (B86) as the primary diagnosis. There were more females than males (χ2 = 31.960, p < 0.001) and patients aged 80 years or older in long-term care hospitals (χ2 = 431.410, p < 0.001). Scabies patients were mainly hospitalized in internal medicine, family medicine, and dermatology for all provider types (χ2 = 170.033, p < 0.001). In long-term care hospitals, the rate of accompanying dementia was 31.9% (χ2 = 193.418, p < 0.001), cerebral infarction was 10.4% (χ2 = 106.271, p < 0.001), and cancer was 2.1% (χ2 = 17.963, p < 0.001), which was higher than other provider types. Additionally, 20.6% in general hospitals (χ2 = 198.952, p < 0.001) had an indwelling catheter, while 49.1% in hospitals and 41.1% in general hospitals were administered steroids (χ2 = 214.440, p < 0.001). The KOH smear test was performed in 11.3% of all inpatients with scabies. We suggest recognizing these characteristics of scabies patients and thoroughly checking the skin lesions during physical examination for early diagnosis and prevention of scabies infection.

Previous Long-term Care Facility Admission as a Risk Factor for Scabies in a Medical Facility

The study aimed to elucidate simple and effective risk factors for scabies infection in the medical environment for early detection and prevention of exposure to other patients and medical staff. We conducted a case-control study of patients who were diagnosed with scabies among hospitalized patients between 2008 and 2019 in an acute-care teaching hospital. Each case was matched according to sex and age with two randomly selected controls without scabies during hospitalization. Clinical characteristics of cases at the time of hospital admission were compared to those of the control group. The scabies group included 34 patients and 68 patients who were included in the control group. After adjusting for confounding factors, previous long-term care facility admission was only associated with scabies (adjusted odds ratio, 5.44; 95% confidence interval, 1.46-20.27; P = 0.012). Careful examination, particularly for patients with previous long-term care facility admission, might be useful for the early detection of scabies.

Susceptibility of patients receiving chemotherapy for haematological malignancies to scabies

BACKGROUND

Scabies is a contagious dermatosis. The risk factors for its transmission remain unclear. A scabies outbreak, involving patients who were receiving chemotherapy for haematological malignancies, occurred at our hospital.

METHODS

The outbreak population was analysed to determine whether the incidence of scabies was higher among contact patients receiving chemotherapy for haematological malignancies.

RESULTS

A patient with crusted scabies was the index case, and 18 of 78 contact healthcare workers (HCWs) and 22 of 135 contact patients were diagnosed with classical scabies. Ten of 17 contact patients with haematological malignancies and 12 of 118 contact patients with other diseases were infected with scabies. The incidence rate was significantly higher among the patients with haematological malignancies (P<0.001). The patients with haematological malignancies had a significantly lower mean minimum neutrophil count than those with other diseases (1159/μL vs 3761/μL, P=0.0012). Most haematological patients did not require special nursing assistance, suggesting that the higher incidence of scabies among these patients resulted from their immunodeficiency rather than greater skin-to-skin contact with infected HCWs.

CONCLUSION

Our study suggests that patients receiving chemotherapy for haematological malignancies are more susceptible to scabies than patients with other diseases, and require stricter protection.

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.

Identifying the time to cure for patients with classic scabies after infection control intervention in acute care hospital settings

Scabies is a re-emerging parasitic disease, particularly in hospitalized patients. This is a retrospective study analyzing adult patients with scabies admitted to a referral university hospital between 2008 and 2018. All patients were treated an average of 3times using scabicides; the median isolation period and time to cure were 14 and 15days, respectively.

Increased risk of bipolar disorder in patients with scabies: A nationwide population-based matched-cohort study

Both scabies and bipolar disorder (BD) are common and troublesome disorders. There are several similarities in both diseases: pruritus, a higher prevalence in crowded environments, and cytokine-mediated inflammatory processes in the pathophysiology. We conducted this nationwide population-based study to investigate the possible relationship between scabies and BD. Based on the National Health Insurance Research Database (NHIRD) of Taiwan, a total of 7096 patients with scabies were identified as a study group and 28,375 matched patients as a control. We tracked the patients in both groups for a 7-year period to identify those newly diagnosed with BD. The demographic characteristics and comorbidities of the patients were analyzed, and Cox proportional hazard regressions were performed to calculate the hazard ratio (HR) of BD. Of the 35,471 patients in this study, 183 (0.5%) patients with newly diagnosed BD were identified, with 58 (0.8%) from the scabies group and 125 (0.4%) from the control group. The patients with scabies had a higher risk of subsequent BD, with a crude hazard ratio of 1.86 and an adjusted hazard ratio of 1.55 (95% confidence interval: 1.12-2.09, P < 0.05). This study shows there is an increased risk for BD among patients with scabies. Immunopathology may contribute to this association.

Pharmacokinetics of ivermectin applied topically by whole-body bathing method in healthy volunteers

As a novel administration method of ivermectin (IVM) for scabies treatment, we proposed a "whole-body bathing method (WBBM)". In this method, the patients would bathe themselves in a bathing fluid containing IVM at an effective concentration. Previously, we demonstrated that WBBM could deliver IVM to the skin but not to the plasma in rats. In the present study, to assess the clinical validity of the method an arm bathing examination (first trial) and a whole-body bathing examination (second trial) were conducted in healthy volunteers. In both the first and second trials, after bathing in fluid containing IVM, the exposure in the stratum corneum was higher compared with that after taking IVM p.o. as reported previously. IVM was not detected in plasma at any sampling point after the whole-body bathing in the second trial. Furthermore no serious adverse events were found. These results in both trials suggest that WBBM can deliver IVM to the human stratum corneum without systemic exposure or serious adverse effects in healthy volunteers, and at concentrations that would be adequate for scabies treatment.

Scabies Among Elderly Korean Patients with Histories of Leprosy

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

Implementing systems thinking for infection prevention: The cessation of repeated scabies outbreaks in a respiratory care ward

BACKGROUND

Root cause analysis (RCA) is often adopted to complement epidemiologic investigation for outbreaks and infection-related adverse events in hospitals; however, RCA has been argued to have limited effectiveness in preventing such events. We describe how an innovative systems analysis approach halted repeated scabies outbreaks, and highlight the importance of systems thinking for outbreaks analysis and sustaining effective infection prevention and control.

METHODS

Following RCA for a third successive outbreak of scabies over a 17-month period in a 60-bed respiratory care ward of a Taiwan hospital, a systems-oriented event analysis (SOEA) model was used to reanalyze the outbreak. Both approaches and the recommendations were compared.

RESULTS

No nosocomial scabies have been reported for more than 1975 days since implementation of the SOEA. Previous intervals between seeming eradication and repeat outbreaks following RCA were 270 days and 180 days. Achieving a sustainable positive resolution relied on applying systems thinking and the holistic analysis of the system, not merely looking for root causes of events.

CONCLUSION

To improve the effectiveness of outbreaks analysis and infection control, an emphasis on systems thinking is critical, along with a practical approach to ensure its effective implementation. The SOEA model provides the necessary framework and is a viable complementary approach, or alternative, to RCA.

Experimental study of pharmacokinetics of external, whole-body bathing application of ivermectin

As a novel method improving the safety of conventional oral ivermectin (IVM) for scabies treatment, we conceived an idea called the "whole-body bathing method". In this method, the patients would bathe themselves in a bathing fluid containing IVM at an effective concentration. To evaluate the feasibility of the method, we investigated the IVM concentration in the skin and plasma after bathing rats in a fluid containing 100 ng/mL of IVM. After the bathing, the concentration of IVM in the skin was more than 400 ng/g wet weight and was maintained until 8 h after the bathing. The concentration was clearly higher than that in patients taking IVM p.o. as previously reported; IVM was not detected in plasma in the present study. Thus, the method would be a preferable drug delivery system for the skin application of IVM compared with p.o. administration.

Scabies in the nursing home

Scabies infection is antediluvian and ubiquitous both in developing and developed countries, yet often neglected. Scabies has a predilection to infect vulnerable subsets of population in crowding conditions, typically applicable to residents in the nursing home. The mite incites a unique immunological response from human hosts. Scabies does not manifest as a singular skin condition and may present atypically in older adults, the majority of nursing home residents, where delay has deleterious consequences. Further, pruritus or itching, the hallmark of scabies infection, is a common complaint from a variety of causes among older adults. Hence, the diagnosis is often delayed or missed. There are several pharmacological treatment options; long-term care practitioners need to understand the characteristics of each agent before selection. Even more relevant is the importance of nonpharmacological aspects of management, crucial in the success of averting spread or outbreaks in long-term care settings.

Scabies mites alter the skin microbiome and promote growth of opportunistic pathogens in a porcine model

Background

The resident skin microbiota plays an important role in restricting pathogenic bacteria, thereby protecting the host. Scabies mites (Sarcoptes scabiei) are thought to promote bacterial infections by breaching the skin barrier and excreting molecules that inhibit host innate immune responses. Epidemiological studies in humans confirm increased incidence of impetigo, generally caused by Staphylococcus aureus and Streptococcus pyogenes, secondary to the epidermal infestation with the parasitic mite. It is therefore possible that mite infestation could alter the healthy skin microbiota making way for the opportunistic pathogens. A longitudinal study to test this hypothesis in humans is near impossible due to ethical reasons. In a porcine model we generated scabies infestations closely resembling the disease manifestation in humans and investigated the scabies associated changes in the skin microbiota over the course of a mite infestation.

Methodology/Principal Findings

In a 21 week trial, skin scrapings were collected from pigs infected with S. scabies var. suis and scabies-free control animals. A total of 96 skin scrapings were collected before, during infection and after acaricide treatment, and analyzed by bacterial 16S rDNA tag-encoded FLX-titanium amplicon pyrosequencing. We found significant changes in the epidermal microbiota, in particular a dramatic increase in Staphylococcus correlating with the onset of mite infestation in animals challenged with scabies mites. This increase persisted beyond treatment from mite infection and healing of skin. Furthermore, the staphylococci population shifted from the commensal S. hominis on the healthy skin prior to scabies mite challenge to S. chromogenes, which is increasingly recognized as being pathogenic, coinciding with scabies infection in pigs. In contrast, all animals in the scabies-free cohort remained relatively free of Staphylococcus throughout the trial.

Conclusions/Significance

This is the first experimental in vivo evidence supporting previous assumptions that establishment of pathogens follow scabies infection. Our findings provide an explanation for a biologically important aspect of the disease pathogenesis. The methods developed from this pig trial will serve as a guide to analyze human clinical samples. Studies building on this will offer implications for development of novel intervention strategies against the mites and the secondary infections.

Scabies is a neglected, contagious skin disease caused by a parasitic mite Sarcoptes scabiei. It is highly prevalent world-wide, and now recognized as a possible underlying factor for secondary bacterial infections with potential serious downstream complications. There is currently few experimental data demonstrating directly that mite infestation promotes bacterial infections. Due to remarkable similarities in terms of immunology, physiology and skin anatomy between pigs and humans, we developed a sustainable porcine model enabling in vivo studies of scabies mite infestations. Here, we investigated the impact of the scabies mite infection on the normal pig skin microbiota in the inner ear pinnae in young piglets. Samples obtained prior to, during infection and after acaricide treatment were analyzed by sequencing of bacterial 16S rDNA. We report that scabies infestation has an impact on the host's skin microbiota. Staphylococcus abundance increased with the onset of infection and remained beyond treatment and healing. A shift from commensal to pathogenic Staphylococci was observed. This study supports the link between scabies and Staphylococcus infections, as seen in humans. It is the first in vivo demonstration of a mite induced shift in the skin microbiota, providing a basis for a similar study in humans.

Risk factors for delayed diagnosis of scabies in hospitalized patients from long-term care facilities

Background

Delayed diagnosis of scabies can cause an institutional outbreak, which causes considerably economic burden to control. This study was to find the risk factors for delayed diagnosis of scabies in hospitalized patients from long-term care facilities.

Methods

We conducted a retrospective analysis of the hospitalized patients from long-term care facilities, diagnosed to have scabies between January 2006 and December 2008. A stepwise logistic regression analysis was performed to determine the risk factors for delayed diagnosis of scabies.

Results

A total of 706 episodes with scabies were identified retrospectively in 399 hospitalized patients from long-term care facilities. Of these, 44 episodes were considered as delayed diagnosis of scabies. These patients were more associated with chronic usage of steroid (73% vs. 10%, P < 0.001) and had longer duration of hospitalization than the others (30 vs. 13 days, P < 0.001). After logistic regression, steroid therapy was the risk factor of delayed diagnosis of scabies (odds ratio: 23.493).

Conclusions

In the patients from long-term care facilities, clinical physicians should pay more attention to those with chronic usage of steroid to avoid delayed diagnosis of scabies.

Keywords

Scabies; Delayed diagnosis; Risk factor; Long-term care facility

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

A considerable number of patients suffer recurrence of scabies. To elucidate risk factors for recurrence of scabies, we compared patients who experienced scabies recurrence and those who suffered scabies only once. We conducted a retrospective review of medical records of all scabies patients in a long-term care hospital for the elderly (300 beds; six wards) for a period of 42 months to determine frequency of scabies onsets, underlying diseases, history of treatment, and demographic data such as age and sex. One hundred and forty-eight patients and five hospital staff members suffered scabies during the 42-month study period. All staff members and 98 patients had no recurrence, while 50 patients experienced at least one recurrence of scabies. The cumulative number of scabies diagnoses was 228. The rates of scabies onset and recurrence were considerably different among wards. The dementia unit showed the highest rate of onset and recurrence. In addition to frequent exposure to infectious sources, problematic behavior, such as lying in other patients beds, might cause the high recurrence rate in dementia units. Higher serum total lymphocyte count and topical use of γ-benzene hexachloride were associated with lower risk of scabies recurrence. Recurrence of scabies is not uncommon among elderly patients in institutional settings. Impaired immunity may be a risk factor for recurrence of scabies. Groups with a high onset rate of scabies pose a high likelihood of recurrence. Problematic behavior of demented patients may increase the risk of recurrence. Use of effective topical treatment may effectively prevent recurrence.

Factors related to missed diagnosis of incidental scabies infestations in patients admitted through the emergency department to inpatient services

OBJECTIVES

Scabies is highly contagious and requires prompt diagnosis and implementation of infection control measures to prevent transmission and outbreaks. This study investigated the clinical and administrative correlates associated with missed diagnosis of scabies in an emergency department (ED).

METHODS

This was a retrospective study of patients with incidental scabies infestations who were admitted to a university hospital via the ED during a 4-year period.

RESULTS

A total of 135 inpatients were identified as having scabies; among them, 111 patients (82%) had visited the ED. Scabies were diagnosed during the ED stay in 39 of 111 patients (35%), while the diagnosis was missed in the ED in 72 patients (65%). Although no geographic clusters suggestive of nosocomial scabies transmission were registered, 160 medical workers and one hospitalized patient received prophylactic treatment due to direct skin-to-skin contact with inpatient scabies cases during the study period. Overcrowding (odds ratio [OR] = 8.4; 95% confidence interval [CI] = 1.9 to 38.0) and time constraints (OR = 8.2; 95% CI = 1.9 to 34.7) in the ED were associated with a missed diagnosis of scabies during ED stay. Patients with lower illness severity scores were at higher risk for failure to diagnose and to treat scabies prior to hospital admission (OR = 5.7; 95% CI = 1.6 to 20.9).

CONCLUSIONS

Missed diagnoses of scabies during ED stay may result in nosocomial spread and increase the unnecessary use of prophylactic treatments. ED overcrowding, time constraints, and less severe illness compromise ED recognition of scabies. Health care workers should be especially alert for signs of scabies infestations under these conditions.

Scabies in healthcare settings

PURPOSE OF REVIEW

In industrialized countries, epidemics of scabies are mainly described within families or in institutions such as healthcare settings. Control of institutional scabies is associated with a considerable working and economic burden, but guidelines for the management are scarce.

RECENT FINDINGS

The prevalence of institutional scabies is probably underestimated. Identified risk factors for institutional scabies outbreaks include the institution type, extensive physical contact with patients and movement of patients, the existence of crusted scabies, a long diagnostic delay and failures in implementation of infection control or treatment plans.Atypical clinical features (hyperinfestation, scabies in the elderly or in children) may be misdiagnosed. Control of institutional scabies outbreaks relies on prompt recognition of the index case, constitution of an outbreak management team, determination of the extent of the outbreak and risk factors for spread, immediate implementation of infection control practices, adequate education of all involved persons, simultaneous treatment of cases and of all exposed individuals and concomitant environmental disinfection. Prolonged surveillance is imperative to eradicate scabies.

SUMMARY

The inclusion of institutionalized patients in randomized controlled trials would be beneficial as present data concerning scabicide effectiveness are obtained from trials that recruited individual participants and do not take into account a global strategy.