Antibody Responses to Sarcoptes scabiei Apolipoprotein in a Porcine Model: Relevance to Immunodiagnosis of Recent Infection

No commercial immunodiagnostic tests for human scabies are currently available, and existing animal tests are not sufficiently sensitive. The recombinant Sarcoptes scabiei apolipoprotein antigen Sar s 14.3 is a promising immunodiagnostic, eliciting high levels of IgE and IgG in infected people. Limited data are available regarding the temporal development of antibodies to Sar s 14.3, an issue of relevance in terms of immunodiagnosis. We utilised a porcine model to prospectively compare specific antibody responses to a primary infestation by ELISA, to Sar s 14.3 and to S. scabiei whole mite antigen extract (WMA). Differences in the antibody profile between antigens were apparent, with Sar s 14.3 responses detected earlier, and declining significantly after peak infestation compared to WMA. Both antigens resulted in >90% diagnostic sensitivity from weeks 8–16 post infestation. These data provide important information on the temporal development of humoral immune responses in scabies and further supports the development of recombinant antigen based immunodiagnostic tests for recent scabies infestations.

The impact of sarcoptic mange Sarcoptes scabiei on the British fox Vulpes vulpes population

1. Disease epizootics can significantly influence host population dynamics and the structure and functioning of ecological communities. Sarcoptic mange Sarcoptes scabiei has dramatically reduced red fox populations Vulpes vulpes in several countries, including Britain, although impacts on demographic processes are poorly understood. We review the literature on the impact of mange on red fox populations, assess its current distribution in Britain through a questionnaire survey and present new data on resultant demographic changes in foxes in Bristol, UK. 2. A mange epizootic in Sweden spread across the entire country in < 10 years resulting in a decline in fox density of up to 95%; density remained lowered for 15–20 years. In Spain, mange has been enzootic for > 75 years and is widely distributed; mange presence was negatively correlated with habitat quality. 3. Localized outbreaks have occurred sporadically in Britain during the last 100 years. The most recent large-scale outbreak arose in the 1990s, although mange has been present in south London and surrounding environs since the 1940s. The questionnaire survey indicated that mange was broadly distributed across Britain, but areas of perceived high prevalence (> 50% affected) were mainly in central and southern England. Habitat type did not significantly affect the presence/absence of mange or perceived prevalence rates. Subjective assessments suggested that populations take 15–20 years to recover. 4. Mange appeared in Bristol's foxes in 1994. During the epizootic phase (1994–95), mange spread through the city at a rate of 0.6–0.9 km/month, with a rise in infection in domestic dogs Canis familiaris c. 1–2 months later. Juvenile and adult fox mortality increased and the proportion of females that reproduced declined but litter size was unaffected. Population density declined by > 95%. 5. In the enzootic phase (1996–present), mange was the most significant mortality factor. Juvenile mortality was significantly higher than in the pre-mange period, and the number of juveniles classified as dispersers declined. Mange infection reduced the reproductive potential of males and females: females with advanced mange did not breed; severely infected males failed to undergo spermatogenesis. In 2004, Bristol fox population density was only 15% of that in 1994.

Evaluation of a Commercial ELISA for the Detection of Antibodies to Sarcoptes scabiei in Wild Boar (Sus scrofa).

Sarcoptic mange occurs in free-ranging wild boar (Sus scrofa) but has been poorly described in this species. We evaluated the performance of a commercial indirect enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of sarcoptic mange in domestic swine when applied to wild boar sera. We tested 96 sera from wild boar in populations without mange history ("truly noninfected") collected in Switzerland between December 2012 and February 2014, and 141 sera from free-ranging wild boar presenting mange-like lesions, including 50 live animals captured and sampled multiple times in France between May and August 2006 and three cases submitted to necropsy in Switzerland between April 2010 and February 2014. Mite infestation was confirmed by skin scraping in 20 of them ("truly infected"). We defined sensitivity of the test as the proportion of truly infected that were found ELISA-positive, and specificity as the proportion of truly noninfected that were found negative. Sensitivity and specificity were 75% and 80%, respectively. Success of antibody detection increased with the chronicity of lesions, and seroconversion was documented in 19 of 27 wild boar sampled multiple times that were initially negative or doubtful. In conclusion, the evaluated ELISA has been successfully applied to wild boar sera. It appears to be unreliable for early detection in individual animals but may represent a useful tool for population surveys.

Is ITS-2 rDNA suitable marker for genetic characterization of Sarcoptes mites from different wild animals in different geographic areas?

The present study examined the relationship among individual Sarcoptes scabiei mites from 13 wild mammalian populations belonging to nine species in four European countries using the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) as genetic marker. The ITS-2 plus primer flanking 5.8S and 28S rDNA (ITS-2+) was amplified from individual mites by polymerase chain reaction (PCR) and the amplicons were sequenced directly. A total of 148 ITS-2+ sequences of 404bp in length were obtained and 67 variable sites were identified (16.59%). UPGMA analyses did not show any geographical or host-specific clustering, and a similar outcome was obtained using population pairwise Fst statistics. These results demonstrated that ITS-2 rDNA does not appear to be suitable for examining genetic diversity among mite populations.

Crusted scabies is associated with increased IL-17 secretion by skin T cells

Scabies is an ectoparasitic infestation by the mite Sarcoptes scabiei. Although commonly self-limiting, a fraction of patients develop severely debilitating crusted scabies. The immune mechanisms underlying the development of crusted scabies are unclear, and undertaking longitudinal infection studies in humans is difficult. We utilized a porcine model to compare cellular immune responses in peripheral blood and skin of pigs with different clinical manifestations of scabies (n = 12), and in uninfected controls (n = 6). Although clinical symptoms were not evident until at least 4 weeks post-infestation, the numbers of peripheral IFNγ-secreting CD4+ T cells and γδ T cells increased in infected pigs from week 1 post-infestation. γδ T cells remained increased in the blood at week 15 post-infestation. At week 15, skin cell infiltrates from pigs with crusted scabies had significantly higher CD8+ T cell, γδ T cell and IL-17+ cell numbers than those with ordinary scabies. Peripheral IL-17 levels were not increased, suggesting that localized skin IL-17-secreting T cells may play a critical role in the pathogenesis of crusted scabies development. Given the potential of anti-IL-17 immunotherapy demonstrated for other inflammatory skin diseases, this study may provide a novel therapeutic avenue for patients with recurrent crusted scabies.

Pathology of sarcoptic mange in red foxes (Vulpes vulpes): macroscopic and histologic characterization of three disease stages

Sarcoptic mange is a highly contagious skin disease that can have a devastating impact on affected wild mammal populations. There are notable variations in the clinical and pathologic picture of sarcoptic mange among species and among conspecifics. However, the origin of these variations is unclear. We propose a classification scheme for skin lesions associated with Sarcoptes scabiei infestation to provide a basis for a subsequent risk factor analysis. We conducted a case-control study focused on macroscopic and histologic examination of the skin, using 279 red foxes (Vulpes vulpes) found dead or shot in Switzerland between November 2004 and February 2006. All animals were submitted to gross necropsy following a detailed protocol. Selection criteria for cases (n=147) vs. controls (n=111) were the presence or absence of mange-like lesions, mite detection by isolation or histologic examination, and serologic testing for S. scabiei antibodies. Characteristic features of mange lesions were scored macroscopically in all foxes and histologically in 67 cases and 15 controls. We classified skin lesions and associated necropsy findings into three types of mange: A) early stage (n=45): focal-extensive skin lesions, thin crusts, mild to moderate alopecia, few mites, numerous eosinophils, and mild lymph node enlargement; B) hyperkeratotic, fatal form (n=86): generalized skin lesions, thick crusts with or without alopecia, foul odor, abundance of mites, numerous bacteria and yeasts, numerous lymphocytes and mast cells, severe lymph node enlargement, and emaciation; C) alopecic, healing form (n=16): focal lesions, no crusts, severe alopecia, hyperpigmentation and lichenification, absence of mites, mixed cell infiltration, and rare mild lymph node enlargement. We hypothesize that after stage A, the animal either enters stage B and dies, or stage C and survives, depending on largely unknown extrinsic or intrinsic factors affecting the host ability to control mite infestation.

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.

Scabies mite inactivated serine protease paralogues are present both internally in the mite gut and externally in feces

The scabies mite, Sarcoptes scabiei, is the causative agent of scabies, a disease that is common among disadvantaged populations and facilitates streptococcal infections with serious sequelae. Previously, we encountered large families of genes encoding paralogues of house dust mite protease allergens with their catalytic sites inactivated by mutation (scabies mite inactivated protease paralogues [SMIPPs]). We postulated that SMIPPs have evolved as an adaptation to the parasitic lifestyle of the scabies mite, functioning as competitive inhibitors of proteases involved in the host–parasite interaction. To propose testable hypotheses for their functions, it is essential to know their locations in the mite. Here we show by immunohistochemistry that SMIPPs exist in two compartments: 1) internal to the mite in the gut and 2) external to the mite after excretion from the gut in scybala (fecal pellets). SMIPPs may well function in both of these compartments to evade host proteases.

Prevalencia de Escabiosis en usuarios que consultan la Unidad Comunitaria de Salud Familiar Tecapán, departamento de Usulután de Mayo a Julio de 2014

La presente investigación, tuvo como objetivo establecer la prevalencia de Escabiosis en los usuarios que consultaron la Unidad Comunitaria de Salud Familiar Tecapán durante el período comprendido de mayo a julio de 2014. La metodología: el estudio fue de tipo prospectivo, transversal, descriptivo y de laboratorio. El muestreo se realizó en 63 usuarios que consultaron con sintomatología sugestiva a escabiosis y con lesiones características de la enfermedad, esta población está representada tanto por el sexo femenino como masculino, con edades que van desde 1 mes hasta 56 años; para la recolección de la información se utilizó una cédula de entrevista compuesta por 10 preguntas semi abiertas en la cual se evaluaron los factores de riesgo de la Escabiosis, también se utilizó la guía de observación para identificar lesiones características de la enfermedad y se obtuvo muestras de raspado de lesión para analizarlas en el laboratorio de Microbiología de la Facultad Multidisciplinaria Oriental de la Universidad de El Salvador para identificar la presencia o ausencia de Sarcoptes scabiei. Resultado: La prevalencia de Escabiosis encontrada fue del 22.22%, determinando que los principales factores de riesgo son: el contacto con animales domésticos con 85.71%, un 64.29 % de usuarios tienen familiares con la enfermedad y un 60.30 % no sabe que es Escabiosis. El grupo etario más afectado fue el comprendido entre las edades de 1 mes a 5 años con un 50%, por sexo predominó el femenino con 27.03% y el masculino con un 15.38%, según la procedencia un 25% corresponde a la zona rural y un 17.39% de la zona urbana. Conclusión: Estadísticamente se aceptó la hipótesis nula: La prevalencia de escabiosis en usuarios que consultan la Unidad Comunitaria de Salud Familiar Tecapán es menor o igual al 20%. En base a los resultados obtenidos en el laboratorio se encontraron los siguientes estadios de Sarcoptes scabiei: huevo 92.90% y adulto un 7.10%; no se encontraron los estadios de larva y ninfa.

An exploratory study to assess the activity of the acarine growth inhibitor, fluazuron, against Sarcoptes scabei infestation in pigs

Background: The most common treatments for scabies in human and veterinary settings are topical 5% permethrin or systemic treatment with ivermectin. However, these treatments have very little activity against arthropod eggs, and therefore repeated treatment is frequently required. In-vitro, biochemical and molecular studies have demonstrated that human mites are becoming increasingly resistant to both acaricides. To identify alternate acaricides, we undertook a pilot study of the in vivo activity of the benzoylphenyl urea inhibitor of chitin synthesis, fluazuron, in pigs with sarcoptic mange. Findings: Pigs (n = 5) were infested with S. scabei var suis, and randomised to treatment at the start of peak infestation with fluazuron at a dose of 10 mg/kg/day per os for 7 days (n = 3) or no treatment (n = 2). Clinical scores, skin scrapings for mite counts and blood sampling for pharmacokinetic analysis were undertaken. Fluazuron was well absorbed in treated pigs with measureable blood levels up to 4 weeks post treatment. No adverse effects were observed. Modest acaricidal activity of the compound was observed, with a reduction in severity of skin lesions in treated pigs, as well as a reduction in number of scabies mite's early life stages. Conclusions: The moderate efficacy of fluazuron against scabies mites indicates a lead to the development of alternate treatments for scabies, such as combination therapies that maybe applicable for human use in the future.

Sarcoptes-World Molecular Network (Sarcoptes-WMN): integrating research on scabies

Parasites threaten human and animal health globally. It is estimated that more than 60% of people on planet Earth carry at least one parasite, many of them several different species. Unfortunately, parasite studies suffer from duplications and inconsistencies between different investigator groups. Hence, groups need to collaborate in an integrated manner in areas including parasite control, improved therapy strategies, diagnostic and surveillance tools, and public awareness. Parasite studies will be better served if there is coordinated management of field data and samples across multidisciplinary approach plans, among academic and non-academic organizations worldwide. In this paper we report the first 'Living organism-World Molecular Network', with the cooperation of 167 parasitologists from 88 countries on all continents. This integrative approach, the 'Sarcoptes-World Molecular Network', seeks to harmonize Sarcoptes epidemiology, diagnosis, treatment, and molecular studies from all over the world, with the aim of decreasing mite infestations in humans and animals.

Atividade endectocida de uma nova alternativa terapêutica (S-cifenotrina, Butóxido de piperonila, D-tetrametrina e Ivermectina) em cães

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)