Production performance and pruritic behaviour of pigs naturally infected by Sarcoptes scabiei var. suis in a contact transmission experiment

Reports on the effects of mange on the production performance of pigs are conflicting. So far, studies have used experimental infections, by depositing encrusted lesions from chronically infected pigs into the ears of experimental pigs. However, this is a poor representation of what happens under natural field conditions. The purpose of our study was to quantify the effects of sarcoptic mange on production performance and pruritus in pigs that were infected by contact with S. scabiei var. suis-infected pigs. A total of 80 piglets were matched by sex and weight and randomly divided between experimental and control compartments. In the experimental compartment, each of three naturally S. scabiei var. suis-infested pigs were randomly allocated to three pens with 13 susceptible pigs each. From day 0 to 35, the growth performance of pigs in the experimental compartment was significantly (P=0.04) worse (35 g/d) than of pigs in the control compartment. From day 35 to 112, there was a statistical trend (P=0.10) that the growth performance of pigs in the experimental compartment was lower (50 g/d) than that of pigs in the control compartment. For the complete fattening period (0-112 or more days), the growth performance of pigs in the experimental compartment was significantly (P=0.05) worse (41 g/d) than that of pigs in the control compartment. Mean feed conversion ratio (kg feed per kg gain) was 2% higher in the experimental compartment compared with the control compartment. Pigs in the experimental compartment had a nine times (95% CI: 2 - 44) higher chance of showing pruritic behaviour than pigs in the control compartment.     

Hemagglutinating factor in an extract of Sarcoptes scabiei var. suis (De Geer)

A naturally occurring hemagglutinating factor to tanned human O positive, ovine and porcine erythrocytes was found in extracts from Sarcoptes scabiei var. suis. This hemagglutinating factor did not react with bovine, equine or avian erythrocytes. This factor was demonstrated by microscopic examination of the tanned erythrocytes and by the passive hemagglutination assay.     

Experimental Sarcoptes scabiei infestation in pigs: (1) pathogenesis.

Animals were experimentally infested with Sarcoptes scabiei var suis at weekly intervals between birth and five weeks of age. Excoriations were observed on the luminal surface of the ear seven days after the initial infestation. Encrusted lesions developed in the ears of all pigs between the third and eighth weeks but spontaneously regressed and disappeared by the 14th week. A generalised pruritus, accompanied by focal erythematous skin lesions developed in a majority of pigs between seven and 11 weeks of age. The presence of pruritus was associated with an eosinophilia and histological changes in the skin which were consistent with an allergic reaction. The results are discussed in relation to their diagnostic significance and their importance in the control and eradication of the disease.     

Humoral Antibody Response to Experimental Sarcoptes scabiei var. vulpes Infection in the Dog

Abstract— Humoral antibody responses to experimental Sarcoptes scabiei var. vulpes infection in 10 beagle dogs were demonstrated by an ELISA in three experiments. In the first experiment, four dogs, infected with a relatively high dose of S. scabiei, seroconverted 2 weeks post infection. All four animals showed clinical signs of sarcoptic mange. In the second experiment, six dogs were infected with a relatively low dose of S. scabiei. Three of the dogs developed clinical signs of sarcoptic mange and only in these three were antibodies to S. scabiei demonstrated. Seroconversion occurred 4–5 weeks post infection. The six dogs infected with a low dose of Sarcoptes were re-infected with a relatively low dose of mites 7 weeks after the spontaneous clinical recovery of the three dogs that had exhibited mange following the primary infection. The later three dogs showed a specific antibody response within 1 week and the other three dogs within 2 weeks following the re-infection. Resumen En tres experimentos se demostraron las respuestas humorales de anticuerpos a la infección con Sarcoptes scabiei var. vulpes en 10 perros de la raza Beagle por medio de pruebas ELISA. En el primer experimento cuatro de los perros infectados con una dosis relativamente alta de Sarcoptes, seroconvirtieron 2 semanas despues de la infección. Estos cuatro animales mostraban cuadro clínico de infección. En un segundo experimento seis de los perros se sometieron a una dosis relativamente baja del ácaro. Solo tres de estos perros demostraron cuadro clínico de la infección, y en éstos animales exclusivamente se encontraron anticuerpos de S. scabiei. Cinco o seis semanas después de la infección se produjo la seroconversión de los mismos. Los seis perros infectados con una dosis baja se volvieron a re-infectar con otra dosis relativamente baja siete semanas después de la recuperatión clínica espontánea de los tres perros que habían padecido el cuadro clínico de la sarna, después de la infección previa. Los últimos tres perros produjeron una respuesta de anticuerpos específica en una semana, y los otros tres perros en dos semanas después de la infección.     

Clinical Picture and Antibody Response in Pigs Infected by Sarcoptes scabiei var, suis

Abstract— Clinical signs and antibody responses were observed in juvenile SPF-pigs experimentally infected with Sarcoptes scabiei var. suis and in neonatal pigs born to a sow cronically infected with S. scabiei. Mange became evident after 2–3 weeks. Three SPF-pigs, which were infected twice, developed clinical signs a few days earlier than three other SPF-pigs infected once. Serum antibodies to S. scabiei were demonstrated by an ELISA, using an extract of S. scabiei var. vulpes as an antigen, 5–7 weeks after the experimental infection and significant levels of antibody to S. scabiei were seen during the acute and chronic phases of the disease. Pruritus was seen at 4 days of age in piglets born to the infected sow. Maternal antibodies to S. scabiei were demonstrated within 6 h reaching mean maximum levels between 24 and 48 h after birth. Résumé— Les symptômes et la réponse anticorps chez des pores SPF infestés expérimentalement par Sarcoptes scabiei var. suis et des porcelets nouveaux nés dans une porcherie infectée chroniquement par Sarcoptes scabiei one étéétudiés. La gale est apparue au bout de deux à trois semaines. Trois pores SPF, qui ont été infectés deux fois, ont présenté des symptômes quelques jours avant trois porcelet SPF infectés une seule fois. Les anticorps spécifiques de Sarcoptes scabiei ont été mis en évidence par une technique EIA, utilisant comme antigène des extraits de Sarcoptes scabiei tar. vulpes, 5 à 7 semaines après l'inoculmation. Des taux significatifs ont été observés tant pendant la phase aigue aue la phase chronique de la maladie. Le prurit était observé dès l'âge de 4 jours pour les porcelets nés dans la porcherie infectée. Des anticorps maternels spécifiques Sarcoptes scabiei ont été mis en evidence dès la sixième heure, avec des pics maximum entre 24 et 48 heures après la mise-bas.     

Preventing transmission of Sarcoptes scabiei var. suis from infested sows to nursing piglets by a prefarrowing treatment with doramectin injectable solution

Studies were conducted at swine facilities in Illinois and North Carolina to evaluate the effect of treatment with doramectin injectable solution on transmission prevention of Sarcoptes scabiei var. suis from sows to nursing piglets. Approximately 42 days prefarrowing, 58 mange-free sows were experimentally infested with 200 S. scabiei in each ear. Seven to fourteen days prior to farrowing, 22 sows were given doramectin injectable intramuscularly at a dose of 300 microg/kg of body weight. A total of 21 sows served as untreated controls. Skin scrapings for mite counts and lesion scoring were performed on sows before treatment on day 21, and on either day 35 or 42. Each sow was observed on days 0, 7, 14, 21, 28, and 35 or 42 for the incidence of scratching/rubbing. Skin scrapings, lesion scoring, and observation of scratching/rubbing were performed on the piglets after weaning and at the end of the nursery stage. Geometric mean mite counts of the untreated sows were 0.70 and 0.26 on days 21 and 35 or 42, respectively, and 0.00 for doramectin-treated sows over the same time periods (P<0.05). Lesions scores and the incidence of scratching/rubbing were both higher in the untreated sows as compared to the doramectin-treated sows during the same time periods (P<0.05). Geometric mean mite counts of piglets farrowed by untreated sows were 0.50 and 0.60 after weaning and at the end of the nursery stage, respectively, and 0.00 for piglets from doramectin-treated sows over the same time periods (P>0.05). Lesion scores and the incidence of scratching/rubbing were both higher in piglets from untreated sows as compared to those piglets from doramectin-treated sows (P<0.05). Treating S. scabiei-infested sows with doramectin injectable solution before farrowing eliminated mite infestation and prevented the transmission of S. scabiei to piglets.     

Persistent efficacy of doramectin and ivermectin against experimental infestations of Sarcoptes scabiei var. suis in swine

Two studies were performed to compare the persistent efficacy of doramectin and ivermectin in swine experimentally infested with Sarcoptes scabiei var. suis. In the Study 1, 84 pigs were treated with doramectin, ivermectin, or saline solution on Day 0. Pigs were then challenged with mites on Days 0, 7, 14, 21, 28, 35, or 42. Weekly evaluations were performed for 5 weeks following challenge with mites. Weekly evaluations included physical examination for clinical signs of sarcoptic mange and collection of skin scrapings for determination of mite counts. In the Study 2, 80 pigs were treated with doramectin, ivermectin, or saline solution on Day 0, and challenged with mites on Days 3, 6, 9, 12, 15, 18, 21, 24, or 27. Weekly evaluations were performed for 6 weeks after challenge exposure. All negative-control (saline-treated) animals in both studies developed evidence of mite infestation. In the Study 1, doramectin prevented mite infestations 7 days longer than ivermectin. Results from the Study 2 indicated that the persistent efficacy of doramectin was 18 days on the basis of mite recovery. This was twice as long as the persistent efficacy of ivermectin, which was 9 days on the basis of mite recovery.     

Development and Bayesian evaluation of an ELISA to detect specific antibodies to Sarcoptes scabiei var suis in the meat juice of pigs

Samples of ear scrapings, serum and diaphragmatic muscle were collected from 271 fattening pigs at the slaughterhouse. The scrapings were examined for the presence of mites, and tests for specific antibodies to Sarcoptes scabiei var suis in the serum and meat juice were made with an experimental ELISA. The cut-off value for the meat-juice ELISA was estimated at an optical density of 0.5 by receiver operating characteristic curve analysis, on the basis of the cut-off value for the serum ELISA of 0.4. The results of the three tests were used in a Bayesian model to estimate the characteristics of each test. The specificity of the tests of the ear scrapings was considered to be 1 and their sensitivity was estimated by Bayesian analysis to be 0.86, with a 95 per cent confidence interval (CI) of 0.73 to 0.99. The sensitivity of the meat juice ELISA (0.71, 95 per cent CI 0.6 to 0.8) and its specificity (0.77, 95 per cent CI 0.66 to 0.89) were comparable with the sensitivity (0.73, 95 per cent CI 0.6 to 0.8) and specificity (0.81, 95 per cent CI 0.69 to 0.95) of the serum ELISA.     

Sarcoptes scabiei var. suis in a closed pig breeding and fattening herd and control possibilities after treatment

On an Austrian pig breeding and finishing farm containing 13,000 pigs a mange prevalence of 38.7% according to the results of the skin scraping and 28.2% based on serology was determined. Due to the insufficient treatment (single treatment of the sows using Phoxim [Sebacil pour on]), sustainable control was impossible. That could be confirmed by the high number of mange positive gilts and finishing pigs. Before eradication started the following prevalences of mange could be found: sows 6.74% (skin scrapings), respectively 6.18% (serologically), gilts 18.18% resp 28.67%, finishing pigs 54.35% and 38.58%. The breeding stock for eradication was treated with doramectin (Dectomax) injectable solution and the finishing pigs with Ivomec-praemix, both applied twice. The success of treatment of the different farm units and of different age groups was controlled for the following ten months by combined diagnostic methods. In addition to skin scrapings, serum and colostral samples were carried out using a commercially available ELISA licensed for investigation of blood serum and colostrum. After treatment antibodies in the serum of the sows and gilts and Sarcoptes mites in their skin scrapings were detectable for up to four months after treatment. In serum samples of piglets and colostrum samples antibodies against Sarcoptes mites were detectable up to five months after final treatment. Due to the higher level and longer verifiability of antibodies in blood samples of piglets for five months after treatment and high prevalences their use as a diagnostic tool can be recommended. In contrast the use of colostral samples for routine diagnosis should be investigated more thoroughly. The comparison of the results of different diagnostic methods showed that for reliable mange diagnosis combined methods are recommended.     

Experimental infection of red foxes (Vulpes vulpes) with Sarcoptes scabiei var. vulpes

Two of 3 red foxes became experimentally infected with Sarcoptes scabiei v. vulpes isolated from a naturally infected wild fox. The first clinical sign was seen after 10 days. After 30 days hairless patches were observed on the back of one of the foxes while general hair loss continued slowly. On the other fox the only macroscopical changes was tangling of the hair. The foxes died after 67 and 94 days, respectively. Both foxes were anaemic and in very poor condition. Scratching was seen in only 1 of the foxes.     

Efficacy of ivermectin against Sarcoptes scabiei in pigs

The efficacy of orally administered ivermectin against Sarcoptes scabiei was investigated in pigs harbouring experimentally induced infections. Treatment at dosage rates of 300 and 500 microgram per kg body-weight provided 100% control as assessed by mite populations and clinical signs, while at a dose rate of 180 microgram per kg mite populations were substantially reduced but not eliminated.     

Sarcoptes scabiei var. canis refractory to ivermectin treatment in two dogs

A 10-year-old castrated male Shih Tzu presented with severe generalized pruritus. Skin scrapings revealed the presence of Sarcoptes scabiei var. canis. A Yorkshire terrier in the same household simultaneously developed pruritus due to scabies. Both dogs were treated with 300 μg/kg ivermectin, at first orally and then subcutaneously at 14 day intervals. However, live mites were still found on day 35, and the skin condition deteriorated in both dogs. These findings suggested that the S. scabiei in these dogs was clinically refractory to ivermectin. The pruritus in both dogs rapidly and completely disappeared following topical fipronil administration. This appears to be the first report of canine scabies refractory to ivermectin treatment.     

阿维菌素驱除猪疥螨试验

以猪为试验对象，分别用1％阿维菌素注射液和1％伊维菌素注射液按千克体重0.03mL颈部皮下注射治疗自然感染猪疥螨病，设一不用药组作为对照，观察阿维菌素的驱虫效果。用药后第7天，重复用药一次，用药后第14、21、28天虫体转阴率为100％，并且对妊娠母猪、哺乳母猪、哺乳仔猪均无不良影响。     

Serologic herd study and sanitation inspection of Sarcoptes scabiei var. suis infection: a seroepidemiologic study in mange-free and chronically-infected facilities

Sera from 88 pigs chronically infected with Sarcoptes scabiei var.suis were tested in order to evaluate the course of antibody titer with the Chekit Sarcoptest using homogenized Sarcoptes scabiei var.vulpes as antigen. The results were compared with sera of pigs from mange free breeding units. The results of this study show that sera from piglets less than two week old and gilts older than eight months can be used. No positive titers were observed in animals between five weeks and four months of age. In order to avoid false negative results only sera from untreated gilts should be used. The high specificity (99.34%) of the test calculated in a previous study (Zimmermann und Kircher, 1998) is confirmed by these results. Based on the results of the present study testing of colostral samples should be attempted in the future.     

Dot-ELISA检测兔疥螨抗体方法的建立和应用

将从病兔痂皮内收集的疥螨经研磨、冻融、离心后,制成可溶性抗原,作为诊断抗原,建立Dot-ELISA方法检测兔疥螨血清抗体.研究确定了该方法的最佳工作条件.制备的诊断膜片特异性强,不与兔瘟病毒、兔大肠埃希菌、兔附红细胞体等阳性血清反应.膜片具有良好的灵敏性,高免血清作1∶210稀释亦能检出;重复性试验表明该法重复性良好.诊断膜片在4 ℃保存5个月其检测活性不变.结果表明,建立的Dot-ELISA可用于免疥螨抗体的检测.