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At least 19 recordsLinked to original sources
PubMed2003

Expressed sequence tag analysis of Sarcoptes scabiei.

Sarcoptes scabiei is an important parasitic mite in both man and animals. Little is known about the molecular interactions between this pathogen and its host. This is in part explained by the paucity of mite-derived material, including antigens. To extend the knowledge of the molecular repertoire in S. scabiei, we have performed a gene survey by an expressed sequence tag (EST) analysis. A total of 1020 ESTs were generated from an S. scabiei cDNA library. The average sequence read was 510 bp after editing and the overall sequencing success was 89%. Clustering of the sequences resulted in 76 clusters, comprising 36% of the ESTs. Sequence similarity searches showed that almost half of the S. scabiei ESTs could be assigned a putative identity. Many of these transcripts shared similarity with genes involved in basic metabolism and cellular organization. In the data set we also identified several proteases and other types of potential allergens implicated in various disease mechanisms. A relatively large fraction of the ESTs coded for different proteins carrying protease inhibitor-like domains. The clones with no similarity to previously identified genes constituted 11% of our transcripts. The EST data generated in this study will be a valuable resource in further studies of the biology of S. scabiei and in the identification of genes that can serve as potential targets in the control of the parasite.

Animals↗
PubMed1984

Host-seeking behavior of Sarcoptes scabiei.

Sarcoptes scabiei mites perceive specific host stimuli and are attracted to the host. Mites dislodged from the host respond to both host odor and a thermal stimulus and seek its source. The response to thermal and host odor stimuli are independent. Mites in close proximity to the body respond to both stimuli and show no preference for either. At greater distances from the host, odor is the more important stimulus.

Animals↗
PubMed1984

Cross infestivity of Sarcoptes scabiei.

Sarcoptes scabiei var. canis was successfully transferred from the dog to New Zealand White Rabbits, Oryctologus cuniculus. Natural and experimental transfers were accomplished between rabbits. The dog strain transferred to rabbits showed no morphologic changes and was readily transferred back to dogs. Experimental transfer of var. canis to guinea pigs and pigs resulted in only temporary infestation. Attempts to infest haired and hairless mice, thymus-deficient (nude) mice, and rats were unsuccessful. The unsuccessful or transient nature of cross-infestations between some host species and complete cross-infestation in others leads to the conclusion that all S. scabiei varieties are not host-specific but that they do possess some degree of host preference and that physiologic differences between varieties exist.

Animals↗
PubMed2004

Functional analysis and localisation of a delta-class glutathione S-transferase from Sarcoptes scabiei.

The mite Sarcoptes scabiei causes sarcoptic mange, or scabies, a disease that affects both animals and humans worldwide. Our interest in S. scabiei led us to further characterise a glutathione S-transferase. This multifunctional enzyme is a target for vaccine and drug development in several parasitic diseases. The S. scabiei glutathione S-transferase open reading frame reported here is 684 nucleotides long and yields a protein with a predicted molecular mass of 26 kDa. Through phylogenetic analysis the enzyme was classified as a delta-class glutathione S-transferase, and our paper is the first to report that delta-class glutathione S-transferases occur in organisms other than insects. The recombinant S. scabiei glutathione S-transferase was expressed in Escherichia coli via three different constructs and purified for biochemical analysis. The S. scabiei glutathione S-transferase was active towards the substrate 1-chloro-2,4-dinitrobenzene, though the positioning of fusion partners influenced the kinetic activity of the enzyme. Polyclonal antibodies raised against S. scabiei glutathione S-transferase specifically localised the enzyme to the integument of the epidermis and cavities surrounding internal organs in adult parasites. However, some minor staining of parasite intestines was observed. No staining was seen in host tissues, nor could we detect any antibody response against S. scabiei glutathione S-transferase in sera from naturally S. scabiei infected dogs or pigs. Additionally, the polyclonal sera raised against recombinant S. scabiei glutathione S-transferase readily detected a protein from mites, corresponding to the predicted size of native glutathione S-transferase.

Animals↗
PubMed2006

Presence of host immunoglobulin in the gut of Sarcoptes scabiei (Acari: Sarcoptidae).

Sarcoptes scabiei (De Geer) mites burrow in the nonliving stratum corneum of the epidermis of their mammalian hosts. These mites ingest extracellular fluid (serum) that seeps into the burrow from the lower vascular dermis. A strong host antibody response occurs when mites die in the skin. This suggests internal immunogenic proteins are released into the host at this time. Vaccination with internal antigens may be an approach to protect against this mite if host antibody to internal antigens that regulate key physiological processes is ingested along with serum. Our study clearly showed that scabies mites ingest host immunoglobulin as evidenced by the localization of fluorescent-labeled antibody to host immunoglobulin in the anterior midgut and esophagus of fresh mites removed from the host. This is the first study that demonstrates that this nonblood-feeding ectoparasitic mite ingests host antibody while feeding on tissue fluid that seeps into the stratum corneum.

Animals↗
PubMed1996

Immunologic cross-reactivity among various strains of Sarcoptes scabiei.

Varieties of Sarcoptes scabiei from different hosts are highly host specific but they are morphologically indistinguishable. The purpose of this study was to investigate the immunologic cross-reactivity among several varieties of scabies mites using serum from a human scabies patient and from several other species of infested hosts. Homologous and heterologous crossed-immunoelectrophoretic (CIE) analysis of extracts prepared from var. canis (dog) and var. suis (pig) mites yielded very similar antigen profiles. Serum from a human patient infested with var. hominis had circulating IgE that bound to antigens present in extracts prepared from each animal mite variety. Antigen homology was further confirmed by fused peaks on tandem CIE. Additionally, sodium dodecyl sulfate polyacrylamide gel electrophoresis/immunoblot analysis showed that the 2 extracts contained proteins that bound antibody in serum from a var. suis-infested pig, a var. canis-infested dog, var. canis-infested rabbits, and a var. hominis-infested human. The results of this study clearly indicate that different varieties of scabies mites, though host specific, introduce some immunologically cross-reactive molecules into the host. However, each serum from the 4 scabies-infested hosts also contained antibody that was specific for proteins in extract from only 1 variety of mite. These data indicated that each variety of scabies introduced some unique molecules into the host, each strain produced some similar molecules, or both, but different hosts responded immunologically to different sets of these.

Aged↗
PubMed2003

Identification of a homologue of a house dust mite allergen in a cDNA library from Sarcoptes scabiei var hominis and evaluation of its vaccine potential in a rabbit/S. scabiei var. canis model.

Sarcoptes scabiei ("itch mite") causes scabies, a disease of considerable human and veterinary significance. Little work has been done at the molecular level because of the difficulty of obtaining mites. We have used mites in skin from the bedding of crusted scabies patients for the construction of a library of 10(5) cDNAs from S. scabiei var. hominis cloned in the vector pGEX4T-2. We describe the isolation by immunoscreening of 2 clones, one of which (Ssagl) is homologous to and cross-reactive with the house dust mite Euroglyphus maynei allergen M-177, an apolipoprotein from hemolymph. Immunohistochemistry revealed that it is located around the internal organs and cuticle of the mite and in eggs. Although it was not found to be protective in a challenge trial, the rabbits did not exhibit typical crust characteristics. This work shows that it is now possible to conduct such challenge trials with cloned scabies antigens.

Allergens↗
PubMed1979

[Human infestation by Sarcoptes scabiei var. bovis (cattle itch mite)].

Infestation by Sarcoptes scabiei var. bovis in a farmer is reported. He presented with an intensely itching eruption of erythematous papules on forearm, neck and abdomen. An environmental investigation yielded that four of the farmer's cows had mange. Sarcoptes scabiei var. bovis was isolated from skin-scrapings of the cows. Histology from a self-induced lesion revealed that Sarcoptes scabiei var. bovis penetrates the human skin, but does not--in contrast to var. hominis--form burrows. This finding corresponds with the clinical picture. The mite lies subcorneally, compressing the thinned epidermis. The surrounding corneal tissue shows a marked exsudative reaction. The various ways in which mites may infest the human skin are discussed.

Agricultural Workers' Diseases↗
PubMed1987

Sarcoptes scabiei infestation in a cat.

Sarcoptes scabiei infestation was diagnosed in a cat. Clinical signs included thick, crusty, exudative dermatitis on the feet, caudal aspect of the thighs, and tail. Paronychia and dystrophic nails also were observed. The course of the disease was chronic. Concomitant and potentially predisposing additional health problems were suspected, but were not confirmed.

Animals↗
PubMedDate not supplied

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.

Animals↗
PubMed2001

Efficacy of moxidectin 1% injectable against natural infection of Sarcoptes scabiei in sheep.

Thirty ewes naturally infected with Sarcoptes scabiei var. ovis, were allocated into three groups of 10 animals each. Animals in groups B and C were treated on day 0 and on days 0 and +10, respectively, with moxidectin 1% injectable at a dose of 0.2mg moxidectin/kg body weight (BW). Group A remained untreated. Seven days before treatment, the geometric mean of Sarcoptes scabiei var. ovis per square centimeter of skin in groups A, B and C were not significantly different. From the day of treatment to the end of the trial, the average number of mites/cm(2) increased in untreated animals and decreased in groups B and C, but these values were higher for group C. Active lesions produced by S. scabiei var. ovis consistently increased during the trial in the untreated animals; in group B the minimum count occurred on day +56 this reduction being more evident in group C (no lesions on days +49 and +56). Also in this group, the number of cured animals was 100%, therefore, the application of two treatments with moxidectin (group C) showed higher efficacy than a single treatment (group B). Body condition score decreased in the three experimental groups along the trial. All animals were individually weighed on days -1, +28 and at the end of the trial. No adverse reactions were observed in the animals treated with 0.2mg moxidectin/kg BW.

Animals↗
PubMed2002

Elimination of mange mites Sarcoptes scabiei var. suis from two naturally infested Danish sow herds using a single injection regime with doramectin.

Attempts to eliminate Sarcoptes scabiei var. suis were made in 2 naturally infested sow herds, by intramuscular (i.m.) injection of doramectin (Dectomax, Pfizer, New York, USA). A single injection strategy was used. In one of the herds, the environment was treated with an acaricide following dry cleaning of floors, walls and equipment. In the second herd, no environmental treatment was performed. Results were measured by skin lesion scoring, ear scrapings to show Sarcoptes scabiei var. suis, and calculating rubbing index throughout the observation period of 20 months following treatment. Skin lesion scores decreased and stayed low following treatment for the entire observation period. Live Sarcoptes scabiei var. suis mites were isolated prior to treatment from both herds, but not following treatment. Rubbing index decreased following treatment, but was occasionally at or above 0.4. The results of these studies indicate that elimination of Sarcoptes scabiei var. suis from 2 naturally infested herds was successful, using doramectin in a single injection strategy. Precautions must be taken to ensure adequate dosing of every pig, and to avoid reinfestation due to poor biosecurity.

Animals↗
PubMed1989

Efficacy of ivermectin against live mites and eggs of Sarcoptes scabiei in pigs.

Sows infested with Sarcoptes scabiei var. suis (ssvs) were treated with 75, 150 and 300 micrograms/kg of ivermectin by a single subcutaneous injection at the neck region. Compared to the numbers of mites and eggs just before injection, those on post treatment weeks (PTW) 1, 2 and 4 showed significant decreases. Especially at 300 micrograms/kg, the counts showed almost all mites and eggs were eradicated on PTW 1, manifesting ivermectin to possess potential effect on ssve without apparent abnormal side effect. Potential mitocide effect of ivermectin on ssvs was revealed.

Animals↗
PubMed1984

Survival and infectivity of Sarcoptes scabiei var. canis and var. hominis.

Sarcoptes scabiei var. canis served as a suitable model for the study of S. scabiei var. hominis survival. S. scabiei var. canis and var. hominis mites were found to survive off the host for 24 to 36 hours at room conditions (21 degrees C and 40% to 80% relative humidity [RH]), and the canine variety survived 19 days at 10 degrees C and 97% RH. Female mites survived decidedly longer than male mites at comparable conditions. Generally, higher RH values and lower temperatures favored survival, whereas higher temperature and lower RH led to early death. Most canine scabies mites that were held off the host for 36 hours at 75% RH and 22 degrees to 24 degrees C remained infective and penetrated when returned to the host. Live mites of the human variety that were recovered from bed linen slept on by infested patients would also penetrate a host after being held off a host for 96 hours in alternating 12-hour periods of room conditions and refrigeration. Penetration required less than 30 minutes for all life stages of both varieties, and it was accomplished by a mite secretion that dissolved the host tissue. Dislodged mites, particularly those in close proximity to the source, can be a likely source of infestation.

Animals↗
PubMed1997

The behaviour of Sarcoptes scabiei var. hominis in human skin: an ultrastructural study.

The biology of Sarcoptes scabiei var. hominis is poorly understood because of the lack of an in vivo or in vitro propagation system. To obtain more information on the mite behaviour in its natural habitat we conducted an ultrastructural study of burrows in a number of patients with common scabies. Scanning electron microscopy furnished attractive images of the tunnel, parasite body and eggs architecture and demonstrated the presence of holes in the tunnel roof probably representing aeration structures. Transmission electron microscopy showed a marked keratinocyte damage around burrowing mites, well evident ahead of the mite capitulum also. Faecal pellets containing keratinocyte micro-organelles (melanosomes and mitochondria) were documented in posterior midgut. For the first time we disclosed the adhesion mechanism of eggs to the burrow floor. We showed that the typical finger-like projections of the outer layer of the egg shell gradually disappear where the eggs are in contact with the tunnel floor. This allows the inner layer of the egg shell to fuse and stick with the damaged keratinocytes lining the tunnel floor. Our observation substantiates that Sarcoptes scabiei produces a proteolytic substance (salivary secretions?) that has a key role in its life cycle allowing burrowing, feeding and eggs-burrow adhesion.

Adolescent↗
PubMed1998

Findings in vivo of Sarcoptes scabiei with incident light microscopy.

Parasites, especially Sarcoptes scabiei, may represent a difficult diagnostic problem. In many cases, the results of the usual methods for the diagnosis of scabies, such as microscopic identification, can be negative owing to the small number of parasites present in the cornified layer. Moreover, tape stripping or removal of mites with a needle is difficult and sometimes painful, and therefore, not well accepted. We have evaluated the applicability and usefulness of epiluminescence microscopy, a new technique frequently used for the study of pigmented lesions of the skin. Thirty seven patients with the presumptive clinical and/or anamnestic diagnosis of scabies were enrolled in our study. With this method many suspicious sites may be examined within a few minutes without causing any harm or discomfort to the patient.

Animals↗
PubMed1988

Life cycle of Sarcoptes scabiei var. canis.

The life cycle of Sarcoptes scabiei var. canis was systematically investigated in vivo. The life cycle of females and males consisted of an egg, larva, protonymph, and a tritonymph that gave rise to an adult. Development from egg to adult required 10.06-13.16 days for the male and 9.93-13.03 days for the female. Egg incubation times were greater than 50.1 to less than 52.97 hr. Larval duration was between 3.22 and 4.20 days. The durations of protonymphal stages that were destined to become females and males were greater than 2.40 to less than 3.40 days and greater than 2.33 to less than 3.33 days, respectively. Tritonymphs destined to become females and males molted in greater than 2.22 to less than 3.22 days and greater than 2.42 to less than 3.42 days, respectively. During development, all life stages frequently left their burrows and wandered on the skin surface.

Animals↗
PubMed2000

Serum antibody to Sarcoptes scabiei and house dust mite prior to and during infestation with S. scabiei.

In this study, serum antibodies to Sarcoptes scabiei var. canis (SS), Dermatophagoides farinae (DF), and D. pteronyssinus (DP) were determined in 19 healthy, random-source dogs prior to infestation with scabies then again during a primary infestation, cure and challenge infestation with scabies. Prior to scabies infestation, serum of 11 dogs contained faintly detectable amounts of IgE and/or IgG to proteins in SS extract, probably resulting from sensitization to dust mites that share cross-reactive antigenic epitopes with SS. After becoming infested with scabies, the response to SS antigens became stronger with antibodies appearing to more antigens as the scabies infestation progressed. Three of the newly recognized proteins were 170, 155 and 142/133kD and could be used in a diagnostic test since antibodies to them appeared during the primary infestation. In addition, during the primary infestation, 14 of 15 dogs developed IgE to 1-11 new SS proteins in addition to an increase in IgE binding to those proteins recognized prior to infestation. Overall, the strongest antibody responses (IgE and IgG) were exhibited during cure of the first infestation, when dead mites were still present in the stratum corneum. As expected, the antibody response was strong and rapid during challenge when the infestation self-cured. The immunogenic SS proteins identified by serum antibody binding during challenge, when the hosts self-cured, are candidates for inclusion in a vaccine. These candidate proteins are 200, 185, 170, 155, 142/133, 112, 97, 74, 57, 45/42, 32 and 22kD. Some of the proteins in SS that exhibited new or increased antibody binding during the experiment also had IgE and IgG binding to proteins with similar molecular weights in DF and DP extracts. These results illustrate the difficulties involved in understanding and interpreting serum antibody for developing a serological test for the diagnosis of scabies, isolating relevant SS antigens that could be included in a vaccine for prevention of scabies, and for understanding the immune response mechanism to scabies.

Animals↗