An outbreak of scabies in a long-term care facility: the role of misdiagnosis and the costs associated with control

In August 2003, an outbreak of scabies was detected in a Canadian long-term care facility. The outbreak was likely associated with 2 index cases, 1 involving classic scabies and the other involving Norwegian scabies. The scabies control costs totaled CDN $200,000, and the facility received negative publicity for a short period after the outbreak.

PCR-based assay to survey for knockdown resistance to pyrethroid acaricides in human scabies mites (Sarcoptes scabiei var hominis)

Permethrin, in the form of a topical cream, is being increasingly used for community-based programs to control endemic scabies. The development of resistance has reduced the use of pyrethroids for the control of many arthropods of economic and health importance. The best recognized form of pyrethroid resistance, known as knockdown resistance or kdr, has been linked to specific mutations in the target of these agents, the para-homologous voltage-sensitive sodium channel gene (Vssc). To develop tools to study resistance to pyrethroid acaricides, we cloned 3711 and 6151 bp, respectively, of cDNA and genomic fragments of the Vssc gene from scabies mite, Sarcoptes scabiei. The sequence encompasses the major polymorphic amino acid residues associated with pyrethroid resistance. A polymerase chain reaction-based strategy has been developed that enables genotyping individual scabies mites. This will facilitate early detection and monitoring of pyrethroid resistance in scabies mite populations under drug selection pressure.

Progress and opportunities in the development of vaccines against mites, fleas and myiasis-causing flies of veterinary importance

Despite the potential benefits offered by vaccination against ectoparasites, there have been few commercial successes with this strategy, in spite of sustained efforts using increasingly sophisticated techniques. This review outlines the progress and challenges offered by recent research into vaccination against some of the major ectoparasites of veterinary importance, and provides an insight into the opportunities arising from our increased understanding of the immunology of host-parasite relationships and the potential for exploitation of this knowledge and that arising from new genomic data provided by expressed sequence tag projects.

[Approach to the patient with scabies]

Scabies is an ectoparasitosis caused by Sarcoptes scabiei. Clinical types can be highly variable. There might be a problem in diagnosis due to difficulty in detecting the parasite and atypical clinical features. Delayed diagnosis may be the cause of outbreaks for people living in overcrowded places such as poorhouses, orphanages and barracks. The different types of treatment have been discussed as well as rules for prevention.

[Nosocomial outbreak of scabies in a psychiatric hospital--epidemiological assessment and prophylactic treatment with oral ivermectin]

OBJECTIVES

To evaluate the effectiveness of mass treatment with ivermectin of scabies outbreak in institutional settings. To determine the factors, such as host susceptibility and scabetic exposure level associated with the onset of scabies.

METHODS

The authors investigated a nosocomial scabies outbreak in a close psychiatric ward. The index case was a man with steroid-induced localized crusted scabies. Twenty-six patients were diagnosed with scabies, 4 of them had relapse of scabies, while no staff was infested. Despite frequent surveillance and treatment of symptomatic patients with 1% gamma-benzenehexachloride (gamma-BHC: Lindane), new cases were observed. Thus, all 69 patients in the ward were treated with ivermectin (200 microg/kg) simultaneously on day 105 of the outbreak (the mass treatment). Patients who had scabies were compared with patients who had no scabies in terms of age, body weight, diabetes, physical functions, topical administration of corticosteroid, proximity to the index patient, and problematic behavior.

RESULTS

The mass treatment was implemented without a significant adverse event. Although two patients developed symptoms of scabies after the mass treatment, no patient in the ward had been diagnosed with scabies since the 98th day of the treatment. Regarding factors associated with the scabies onset, the only statistically significant factor was proximity to the index patient with crusted scabies.

CONCLUSIONS

Oral ivermectin was safe and effective for controlling scabies in institutional settings. The exposure level to scabetic mites was more important than host susceptibility in determining the risk of scabies onset.

Failure to protect goats following vaccination with soluble proteins of Sarcoptes scabiei: Evidence for a role for IgE antibody in protection

Developing an anti-scabies vaccine is thought to be a feasible alternative to chemical control, since animals which have recovered from sarcoptic mange become resistant against mite reinfestation. The purpose of this study was to evaluate the protective value of immune responses developed in animals after immunisation with soluble mite proteins. Soluble proteins from Sarcoptes scabiei were extracted then subjected to ion exchange chromatography, and proteins from the column were eluted step-wise with 0%, 10%, 25% and 50% of 1 M solution of NaCl in a Tris buffer. Each protein fraction was concentrated and dialysed against PBS. To evaluate the immunogenicity of the fractions, 36 goats were allocated into six groups, group1 goats were unvaccinated, group 2 were vaccinated with intact soluble mite proteins, and groups 3-6 were vaccinated respectively with the fractionated proteins. Vaccinations were conducted four times with 1 mg protein/dose and 4-week intervals between vaccinations. One week after the last vaccination, all goats were challenged with approximately 2000 live mites on the auricles and infestations were allowed to progress for 6 weeks. The severity of lesions caused by the infestation was assessed throughout the study. The challenge caused mange or encrustation dermatitis in all animals and no differences in severity of lesions were observed between vaccinated and unvaccinated control goats. Vaccination with each fraction of the mite proteins invoked high levels of scabies-specific IgG in the serum of all animals but failed to induce specific IgE as determined by Elisa. In contrast, goats challenged experimentally with a primary or repeated mite challenge developed strong serum IgE and IgG antibody responses to Sarcoptes antigens. The latter animals were shown in a previous study to be resistant to reinfestation. The lack of immune protection in the vaccinated animals may be attributed to the absence of protective levels of IgE antibody, and the present findings indicate that allergens and IgE antibody is important in immunity to S. scabiei infection.

[The practice guideline 'The STD consultation' from the Dutch College of General Practitioners; a response from the perspective of dermatology]

Sexually transmitted diseases (STDs) constitute an important health problem in the Netherlands. Although there are several STD outpatient clinics, such facilities remain unavailable outside the larger cities. The members of the Dutch College of General Practitioners, who published the practice guideline on STD consultation, provide the majority of STD care. An important aspect of this guideline is the fact that GPs are able to assess the risk by taking a sexual history and then determine their own policy on additional investigations. This prevents the omission of investigations that would exclude an STD, but carries the risk, at least theoretically, that it may be missed. It is noteworthy that scabies is not discussed in these guidelines. The most important difference between the guidelines followed by dermatological/STD clinics throughout the Netherlands is the level of triage practiced by GPs. It seems that GPs have a well-thought out and responsible policy, which also merits attention from dermatologists/venereologists.

[Nosocomial outbreak of scabies from a Norwegian scabies case]

OBJECTIVE

To describe a nosocomial outbreak of scabies occurred in August 1999, resulting from exposure to an undiagnosed Norwegian scabies case, in Mexico City.

MATERIAL AND METHODS

After reviewing the index case, we isolated the patient and identified secondary scabies cases among employees working in the affected ward, their relatives, and inpatients. Only individuals complaining from skin lesions and pruritus were included as infested cases. Control measures as contact isolation, proper handling of contaminated clothes, and topical treatment were implemented.

RESULTS

A patient with AIDS (index case) with a severe water and electrolyte imbalance was admitted to the Hospital de Infectologia (Infectious Diseases Hospital) of the Centro Medico Nacional La Raza (La Raza National Medical Center) in Mexico City from July 19 to August 20, 1999. Twenty-eight days after the index case admission, scabies cases occurred among health workers. Norwegian scabies was suspected and confirmed by microscopic evidence of the mites on a specimen of scabs from the index case. We identified 48 secondary cases with clinical scabies: 71% health workers, mainly nurses (79%); 23% health workers' relatives; and 6% inpatients. The mean incubation period was 15 days (range 12 to 27). Skin rashes commonly involved the upper extremities (60%) but not the hands.

CONCLUSIONS

This paper highlights the difficulties in diagnosing Norwegian scabies in an immunosuppressed host, as well as the importance of ensuring that health workers follow standard precautions at all times. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

Selective mass treatment with ivermectin to control intestinal helminthiases and parasitic skin diseases in a severely affected population

OBJECTIVE

To assess the short-term and long-term impact of selective mass treatment with ivermectin on the prevalence of intestinal helminthiases and parasitic skin diseases in an economically depressed community in north-east Brazil.

METHODS

An intervention was carried out in a traditional fishing village in north-east Brazil where the population of 605 is heavily affected by ectoparasites and enteroparasites. The prevalence of intestinal helminths was determined by serial stool examination and the prevalence of parasitic skin diseases by clinical inspection. A total of 525 people out of a target population of 576 were treated at baseline. The majority of these were treated with ivermectin (200 microg/kg with a second dose given after 10 days). If ivermectin was contraindicated, participants were treated with albendazole or mebendazole for intestinal helminths or with topical deltamethrin for ectoparasites. Follow-up examinations were performed at 1 month and 9 months after treatment.

FINDINGS

Prevalence rates of intestinal helminthiases before treatment and at 1 month and 9 months after mass treatment were: hookworm disease 28.5%, 16.4% and 7.7%; ascariasis 17.1%, 0.4% and 7.2%; trichuriasis 16.5%, 3.4% and 9.4%; strongyloidiasis 11.0%, 0.6% and 0.7%; and hymenolepiasis 0.6%; 0.4% and 0.5%, respectively. Prevalence rates of parasitic skin diseases before treatment and 1 month and 9 months after mass treatment were: active pediculosis 16.1%, 1.0% and 10.3%; scabies 3.8%, 1.0% and 1.5%; cutaneous larva migrans 0.7%, 0% and 0%; tungiasis 51.3%, 52.1% and 31.2%, respectively. Adverse events occurred in 9.4% of treatments. They were all of mild to moderate severity and were transient.

CONCLUSION

Mass treatment with ivermectin was an effective and safe means of reducing the prevalence of most of the parasitic diseases prevalent in a poor community in north-east Brazil. The effects of treatment lasted for a prolonged period of time.

[Problems related to control of epidemic and persistent outbreaks of scabies]

Experience with control of epidemic and persistent outbreaks of scabies in collectives is presented. Both diagnosis and patient's compliance may pose problems. When diagnosing scabies, not only clinical symptoms but also the dynamics of the spread among persons in collective facilities such as social care and psychiatric in-patient centres should be taken into account and efficacy of the antiscabies medication should be followed up. If diagnosis of scabies is confirmed, it is crucial to prescribe an effective antiscabies medication and to ensure the patient's compliance with treatment, including thorough washing of the body each time before application of the medication, throughout the whole treatment period instead of treating only the symptoms of secondary eczema.

Effects of Sarcoptic Mange and its Control with Oil of Cedrus deodara, Pongamia glabra, Jatropha curcas and Benzyl Benzoate, both with and without Ascorbic Acid on Growing Sheep: Epidemiology; Assessment of Clinical, Haematological, Cell-Mediated Humoral Immune Responses and Pathology

The aim of this study was to evaluate the therapeutic efficacy of commonly used acaricidal drugs in India and also to assess the effect of ascorbic acid (AA) as adjunct therapy in 72 growing sheep with sarcoptic mange, aged 5-6 months and weighing 20.4-31.7 kg. Eight replicates of nine animals were formed based on sex, and day 0 body weight. Another set of 12 healthy sheep (5-6 months old) constituted the healthy control group. Drugs were applied locally on the affected parts daily and recovery changes in skin lesions were observed at the time of every application. L-Ascorbic acid was administered intramuscularly. Skin scrapings were collected daily from each group and examined for the presence of mites. Blood samples from each group were collected and analysed for total erythrocytes, leucocytes, haematocrit, haemoglobin and lymphocytes on 0, 14th and 28th day post-treatment (PT). Cell-mediated (CMI) and humoral immune (HI) responses were assessed on 0 and 28 days PT. Within groups treated with the drug alone, recovery in oil of Jatropha curcas group was faster and lesions were free from mites after the eighth application. For each drug, the recovery was faster with AA as an adjunct therapy when compared with the group treated with the drug alone. Within all groups, recovery in oil of J. curcas plus ascorbic acid (OJC-AA) group was fastest and the lesions were mite-free after three applications. The overall mean values were higher for all haematological parameters in OJC-AA group. Recovery with respect to suppressed CMI and HI responses during infection was also faster in this group. Gross and microscopic pathological studies revealed a marked adverse effect of infection on skin, kidney, spleen and liver. The OJC-AA group indicated faster recovery. It is concluded from this study that oil of J. curcas was found more efficacious in controlling sarcoptic mange in sheep and AA might be beneficial as adjunct in case of sarcoptic mange to get quick recovery with lesser applications of main therapy. However, the pharmacology of AA with reference to health of skin needs to be investigated.

Controlling scabies in institutional settings: a review of medications, treatment models, and implementation

Scabies is a global problem and a significant source of morbidity in nursing home residents and workers because of its highly contagious nature. It is also a problem in hospitals that care for the elderly, the debilitated, and the immunocompromised. New outbreaks continue to occur, despite controlling the recurrent epidemics. Scabies manifests as papules, pustules, burrows, nodules, and occasionally urticarial papules and plaques. Most of the patients with scabies experience severe pruritus. A subset of patients have crusted or Norwegian scabies. These patients, who are usually debilitated or immunocompromised, do not experience the urge to scratch, and therefore do not scratch their own skin. Diagnosis of scabies is based on patient history, physical examination, and demonstration of mites, eggs, or scybala (black or brown football-shaped masses of feces of scabies) on microscopic examination. Scabies can be treated with topical or oral therapies. Topical treatments include 5% permethrin cream, 1% lindane (gamma benzene hexachloride) lotion, 6% precipitated sulfur in petrolatum, crotamiton, malathion, allethrin spray, and benzyl benzoate. Ivermectin, the only oral treatment, is not approved for scabies in the US. Most authorities advocate using a scabicide several times, specifically once a week over a period of 2-3 weeks. In an outbreak of scabies in a nursing home, residents, staff, and frequent visitors should all be treated even if they are not symptomatic. Ivermectin is useful in treating patients with Norwegian or crusted scabies, or who are debilitated. Ivermectin has no serious reported adverse effects. Model treatment plans to stop scabies epidemics have been developed. These plans coordinate treatment of all persons exposed (including ivermectin for debilitated patients), isolation of infected patients, disinfection of objects that patients have come into contact with, and education and reassurance of the medical staff. Failure to coordinate notification, education, treatment, and disinfection leads to failure to control scabies epidemics. Control of epidemics of institutional scabies requires attention to treatment effects and logistics. Treatment is low risk, but cumbersome because many individuals need be treated. It is advisable to restrict, where possible, the number of staff members that deal with scabies patients to limit the spread of the scabies. Prolonged surveillance is required for the eradication of institutional scabies. While the foregoing plans require coordination of all involved personnel and sustained efforts, they are necessary to halt the spread of scabies to patients and staff, to enhance their morale, and to prevent deterioration of labor and public relations.

Scabies and pediculosis

Although scabies and pediculosis are difficult and widespread problems, there are many effective treatments available. Dermatologists play a major role in educating the public in prevention and diagnosis. Although patients are more aware and well informed of the infections because of the Internet and other sources, practitioners are often the most important source of information and treatment in helping to eradicate this worldwide problem.

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.

Nosocomial outbreak of scabies in a hospital in Spain

An outbreak of scabies occurred in a ward of a local hospital in Barbastro (Huesca, Spain), between November 2002 and January 2003. The outbreak was linked to a patient infested with mites when he was admitted to the ward on 1 November 2002. The first case had onset of symptoms on 5 November and the last one on 5 January 2003. Seventeen cases were reported: 11 healthcare workers (HCWs) and six patients.The outbreak was attributed to a delay in diagnosis, and lack of individual protection measures by caregivers. The use of short-sleeved coats is an habitual risk practice in this ward. Contact with fomites, animals, infested clothes or intimate contact with people other than their usual partners were dismissed as risk factors for the infestation. The different groups of caregivers in this ward presented a similar risk of becoming infested, and the mechanism of transmission was probably person to person contact. The implementation of specific guidelines for scabies prevention and treatment, as well as an active surveillance system, were fundamental to the control of this outbreak.

Productivity effects of bovine mange and control with ivermectin

A randomised block design study was conducted to evaluate the effects of mange on cattle. Twenty-four Simmentaler Fleckvieh bulls were formed into eight replicates of three bulls based on Day -56 body weight (288-414 kg). Within replicates bulls were randomly allocated to groups G1: uninfested control, G2: infested control or G3: infested, treated with 0.2mg ivermectin/kg (1% ivermectin injection; IVOMEC, Merial) on Day 0. The G2 and G3 bulls were infested with Sarcoptes/Chorioptes mites on Days -56 and -49. Feed consumption was recorded daily throughout the study (Days -56 to 56). Body weights were measured and serum samples collected. Mites were counted at bi-weekly intervals from Day -14 on. The carcasses of the bulls and the leather produced from their hides were evaluated. Differences between variables were declared significant if P</=0.05. All G2 and G3 bulls became infested. No Sarcoptes or Chorioptes mites were detected on the G3 bulls after Day 14 or Day 28, respectively, whereas G2 bulls maintained infestation throughout the study. From Days -42 to 0, anti-Sarcoptes antibody levels in the two infested groups increased linearly, while levels in the uninfested G1 remained near zero. From Day 14 to Day 56, antibody levels in G2 continued to increase and those in G3 decreased (P</=0.05). From Days -56 to 0, G1 had significantly greater mean weight gain (94.0 kg) than the infested G2 and G3 (76.1 and 75.9 kg). During Days 0-56, G3 gained significantly more weight (90.4 kg) than G2 (58.8 kg), while G1 gained 76.0 kg, not significantly different from either G2 or G3. During Days -56 to 0, the feed conversion efficiency (kg gain/kg feed) of the infested G2 and G3 was significantly lower than that of the uninfested G1; during the 56 days following treatment, feed conversion efficiency of G3 was significantly higher than that of G2, while the uninfested G1 was intermediate. Carcass weight of G2 was significantly lower than those of G1 and G3, which did not differ significantly. Carcass yield, rib eye area and weight of kidney fat of the uninfested G1 were significantly greater than those of G2 and G3. Weights of the adrenal glands, prescapular and precrural lymph nodes were significantly higher for the infested G2 than for the other two groups. Significantly less of leather area from the infested G2 was of usable quality than of the leathers from the uninfested G1 or the infested, treated G3, and the leathers from G2 showed significantly more severe gouging or etching than leathers from the two other groups.