Productivity effects of bovine mange and control with ivermectin

Egyptian mandarin peel oil's anti-scabies potential via downregulation-of-inflammatory/immune-cross-talk: GC-MS and PPI network studies

The current study investigated the scabicidal potential of Egyptian mandarin peel oil (Citrus reticulata Blanco, F. Rutaceae) against sarcoptic mange-in-rabbits. Analysis of the oil's GC-MS identified a total of 20 compounds, accounting for 98.91% of all compounds found. Mandarin peel oil topical application improved all signs of infection, causing a scabicidal effect three days later, whereas in vitro application caused complete mite mortality one day later. In comparison to ivermectin, histopathological analysis showed that the epidermis' inflammatory-infiltration/hyperkeratosis-had disappeared. In addition to TIMP-1, the results of the mRNA gene expression analysis showed upregulation of I-CAM-1-and-KGF and downregulation of ILs-1, 6, 10, VEGF, MMP-9, and MCP-1. The scabies network was constructed and subjected to a comprehensive bioinformatic evaluation. TNF-, IL-1B, and IL-6, the top three hub protein-coding genes, have been identified as key therapeutic targets for scabies. From molecular docking data, compounds 15 and 16 acquired sufficient affinity towards the three screened proteins, particularly both possessing higher affinity towards the IL-6 receptor. Interestingly, it achieved a higher binding energy score than the ligand of the docked protein rather than displaying proper binding interactions like those of the ligand. Meanwhile, geraniol (15) showed the highest affinity towards the GST protein, suggesting its contribution to the acaricidal effect of the extract. The subsequent, MD simulations revealed that geraniol can achieve stable binding inside the binding site of both GST and IL-6. Our findings collectively revealed the scabicidal ability of mandarin peel extract for the first time, paving the way for an efficient, economical, and environmentally friendly herbal alternative for treating rabbits with Sarcoptes mange.

Can Ivermectin kill Sarcoptes scabiei during the molting process?

BACKGROUND

Sarcoptes scabiei is a permanent obligate ectoparasite that lives and reproduces in the epidermis of humans and other mammals worldwide. There is a lack of information on the molting process of Sarcoptes scabiei. Ivermectin is widely used to treat Sarcoptes infection in humans and animals, while the survival of molting Sarcoptes mites in the presence of ivermectin is unknown. The aim of the present study is to investigate the molting process of Sarcoptes mites and assess the activity of ivermectin during the molting process of Sarcoptes mites.

METHODOLOGY/PRINCIPAL FINDINGS

molting Sarcoptes mites were incubated at 35°C and 80% relative humidity and observed hourly until complete molt. Of the 192 molting mites recorded, the longest molt periods for larvae and nymphs were 23 and 30 h, respectively. The activity of ivermectin on molting Sarcoptes mites was also assessed using two concentrations of the drug (0.1 and 0.05 mg/ml). The exposure time for molting mites was determined by 100% mortality of female mites exposed to the solution of ivermectin. While all female mites were killed after exposure to 0.1 mg/ml ivermectin for 2 h and and 0.05 mg/ml for 7 h, 32% and 36% of molting mites survived and successfully molted, respectively.

CONCLUSIONS/SIGNIFICANCE

The present study demonstrated that molting Sarcoptes mites are less susceptible to ivermectin than active mites. As a consequence, mites may survive after two doses of ivermectin given 7 days apart due not only to hatching eggs but also to the resistance of mites during their molting process. Our results provide insight into the optimal therapeutic regimens for scabies and highlight the need for further research on the molting process of Sarcoptes mites.

Myostatin mutation causing double muscling could affect increased psoroptic mange sensitivity in dual purpose Belgian Blue cattle

Belgian Blue cattle are known for their high degree of muscling and good carcass qualities. This high degree of muscling is mainly caused by a mutation in the myostatin gene (MSTN). Although the MSTN mutation is considered as fixed in the Belgian Blue breed, segregation is occurring in a sub-population bred for dual purpose. In the latter population, we observed an association between the mutation in MSTN and susceptibility to psoroptic mange, a skin disease caused by Psoroptes ovis mites that heavily plagues Belgian Blue cattle. In total, 291 animals were sampled and screened for their susceptibility for mange lesions and their MSTN genotype. Via linear mixed modelling, we observed that homozygous mutant animals had a significant increase in the size of mange lesions (+2.51% lesion extent) compared to homozygous wild type. These findings were confirmed with zero-inflated modelling, an animal model and odds analysis. Risk ratios for developing severe mange lesions were 5.9 times as high for homozygous mutant animals. All analyses confirmed an association between the MSTN genotype and psoroptic mange lesion size.

Sarcoptic mange: An emerging panzootic in wildlife

Sarcoptic mange, a skin infestation caused by the mite Sarcoptes scabiei, is an emerging disease for some species of wildlife, potentially jeopardizing their welfare and conservation. Sarcoptes scabiei has a near-global distribution facilitated by its forms of transmission and use of a large diversity of host species (many of those with broad geographic distribution). In this review, we synthesize the current knowledge concerning the geographic and host taxonomic distribution of mange in wildlife, the epidemiological connections between species, and the potential threat of sarcoptic mange for wildlife conservation. Recent sarcoptic mange outbreaks in wildlife appear to demonstrate ongoing geographic spread, increase in the number of hosts and increased virulence. Sarcoptic mange has been reported in at least 12 orders, 39 families and 148 species of domestic and wild mammals, making it one of the most generalist ectoparasites of mammals. Taxonomically, the orders with most species found infested so far include Perissodactyla (67% species from the entire order), Artiodactyla (47%), and Diprotodontia (67% from this order). This suggests that new species from these mammal orders are likely to suffer cross-species transmission and be reported positive to sarcoptic mange as surveillance improves. We propose a new agenda for the study of sarcoptic mange in wildlife, including the study of the global phylogeography of S. scabiei, linkages between ecological host traits and sarcoptic mange susceptibility, immunology of individuals and species, development of control strategies in wildlife outbreaks and the effects of global environmental change in the sarcoptic mange system. The ongoing transmission globally and sustained spread among areas and wildlife species make sarcoptic mange an emerging panzootic in wildlife. A better understanding of sarcoptic mange could illuminate the aspects of ecological and evolutionary drivers in cross-species transmission for many emerging diseases.

Dermal immune responses against Psoroptes ovis in two cattle breeds and effects of anti-inflammatory dexamethasone treatment on the development of psoroptic mange

Psoroptic mange is a common disease of livestock, caused by Psoroptes ovis. Compared to Holstein–Friesian (HF) cattle, the Belgian Blue (BB) cattle breed is highly susceptible to the infestation. However, the mechanism for this difference is still unclear. To determine the factors responsible for this breed susceptibility, the immune response to P. ovis was studied in experimentally infested BB and HF cattle, using clinical signs, histology, immunohistochemical profiling and gene expression analysis of skin biopsies. The mite numbers and lesion area of BB cattle were greater than in HF during the whole study period. Significant influxes of eosinophils in the epidermis and dermis were detected in comparison with the pre-infestation samples in both breeds, with significantly higher eosinophils in BB at 6 weeks post infestation (wpi). Mast cell numbers were unaffected at all stages of infestation in HF, but were significantly elevated relative to pre-infestation in BB cattle at 2 and 6 wpi. The more pronounced cutaneous eosinophilia and higher IL-4 levels at 6 wpi in BB cattle suggest that a Th2-type immune response is underlying the higher susceptibility of the BB breed. In naturally infested BB cattle, development of the psoroptic mange lesions and eosinophils and CD3+ T cell areas were severely depressed after anti-inflammatory treatment with dexamethasone. Together, these results suggest that a stronger Th2-type immune response to P. ovis causes the skin lesions in psoroptic mange in BB cattle and that local anti-inflammatory treatment could potentially be an alternative to control the pathology caused by this parasite.

New insights into the use of a mite count reduction test for the detection of therapeutic acaricide efficacy in Psoroptes ovis in cattle

When used for the evaluation of drug efficacy against Psoroptes ovis, the diagnostic performance of different sampling strategies for a mite count reduction test (MCRT) remains unclear. In the present study, a novel simulation framework was constructed that accounted for relevant biological features of P. ovis infestations in cattle and that was parameterized with field data from 16 farms (154 animals). Second, this framework was applied to explore the impact of study specific factors (number of animals, number of sampled lesions, and number of scrapings per lesion) and biological factors (mite infestation intensity and size of lesions) on the diagnostic performance of MCRT. Its outcome provided a basis to determine the diagnostic performance of MCRT when it was applied according to the World Association for the Advancement in Veterinary Parasitology (WAAVP) and the European Medicine Agency (EMA) guidelines, and to formulate recommendations to ensure a good diagnostic performance of the MCRT. For both guidelines, the MCRT allowed to correctly detect (power 80%) reduced and normal efficacy when the therapeutic efficacy was <70%, and ≥95%, respectively. The results highlighted a reliable diagnostic performance of the MCRT when performed as recommended by WAAVP and EMA for the detection of normal drug efficacy. When used for the detection of reduced efficacy, therapeutic efficacies between 70% and 90% could not be detected with sufficient reliability. The diagnostic performance can be improved by increasing the total number of skin scrapings (increasing the number of animals, number of sampled lesions and/or number of samples per lesion). In order to help researchers and veterinarians to optimize the design of the MCRT to their field settings, the findings were translated into a simple tool.

Ultrasonography of Normal Adrenal Glands in Adult Holstein-Friesian Cows: A Pilot Study

Ultrasonographic reference values for the adrenal glands of cattle have not been reported to date. Adrenal glands can be affected by different pathologies, such as hyperplasia, neoplasia and atrophy (either primary or secondary). The present findings indicate that the right adrenal gland can be easily characterized by transabdominal ultrasound in adult Holstein-Friesian cows, with no apparent influence of age or weight. The right adrenal gland (mean length 3.86 ± 1.39 cm; and mean thickness 1.39 ± 0.26 cm) was consistently and mainly located in the 12th intercostal space. The left adrenal gland was more difficult to locate due to its more medial position, and to the presence of gas in the gastrointestinal tract, so it could not be visualized in most animals (18/25). Its mean length was 3.72 ± 0.95 cm, and mean thickness was 1.36 ± 0.33 cm, in the sagittal section. This is the first report of the ultrasonographic appearance of the adrenal glands of cows and of the corresponding reference preliminary values.

Evaluation of an Indirect ELISA Using Recombinant Arginine Kinase for Serodiagnosis of Psoroptes ovis var. cuniculi Infestation in Rabbits

Psoroptes ovis var. cuniculi is a common ectoparasite of the wild and domestic rabbits worldwide, which causes significant economic losses in commercial rabbit breeding. In China, the diagnosis of rabbits infested with P. ovis var. cuniculi currently relies on detection of clinical signs and Psoroptes mites in skin scrapings by microscopy examination. However, this method is not very efficient in detection of the low mite loads and/or sub-clinical infections. In the present study, we cloned and expressed an arginine kinase homolog gene from P. ovis var. cuniculi (Poc-AK) and used its recombinant protein rPoc-AK to develop an indirect enzyme-linked immunosorbent assay (iELISA) method for diagnosis of P. ovis var. cuniculi infestation in rabbits. The results showed that the rPoc-AK protein was ~61 kDa and had no signal peptide. The rPoc-AK-based iELISA achieved a 94.4% sensitivity and a 88.2% specificity, and was able to detect P. ovis var. cuniculi infection as early as the 1st week post-infection, prior to the appearance of clinical signs. Further field study showed 24.94% (66.33/266) clinically normal rabbits were seropositive with the highest and lowest seropositive rates for California (35.71%) and Belgian (15.14%), respectively. These results suggested that the rPoc-AK has potential as a diagnostic antigen for early P. ovis var. cuniculi infestation in rabbits.

Acaricidal activity of plant-derived essential oil components against Psoroptes ovis in vitro and in vivo

Background

Treatment of Psoroptes ovis in cattle is limited to topical acaricides or systemic treatment with macrocyclic lactones. Treatment failure of macrocyclic lactones has been reported. The aim of this study was to evaluate a potential alternative treatment against P. ovis.

Methods

The acaricidal activity against P. ovis of four plant-derived essential oil components, i.e. geraniol, eugenol, 1,8-cineol and carvacrol, was assessed in vitro and in vivo. In vitro contact, fumigation and residual bioassays were performed. In addition, 12 Belgium Blue cattle were artificially infested and treated topically once a week for three successive weeks with carvacrol in Tween-80 (treatment group) or with Tween-80 alone (control). The efficacy of carvacrol was determined by the reduction in lesion size and mite counts. Six additional animals were topically treated with carvacrol to assess local adverse reactions.

Results

Three components showed a concentration-dependent acaricidal activity in a contact assay, with LC₅₀ of 0.56, 0.38 and 0.26% at 24 h for geraniol, eugenol, and carvacrol, respectively. However, 1,8-cineol showed no activity at any of the tested concentrations in a contact bioassay. In a fumigation bioassay, carvacrol killed all mites within 50 min after treatment, whereas geraniol, eugenol and 1,8-cineol needed 90 to 150 min. Following a 72 h incubation period in a residual bioassay, carvacrol killed all mites after 4 h of exposure to LC_90, while geraniol and eugenol killed all mites only after 8 h exposure. Based on these results, carvacrol was further assessed in vivo. Mite counts in the treatment group were reduced by 98.5 ± 2.4% at 6 weeks post-treatment, while in the control group the mite population had increased. Topical application of carvacrol only caused mild and transient erythema 20 min after treatment. No other side effects were observed.

Conclusions

Considering the strong acaricidal activity of carvacrol in vitro and in vivo and the mild and transient local side effects, carvacrol shows potential as an acaricidal agent in the treatment of P. ovis in cattle.

The seroprevalence of Sarcoptes scabiei var. canis and its associated risk factors in dogs in Ibadan, Southwest Nigeria

This study investigated the use of SARCOPTES-ELISA DOG KIT as a diagnostic tool in detecting anti-mite antibodies, establishing the prevalence of scabies in dogs and the associated risk factors of canine mange occurrence. A total of 384 dogs (149 males and 235 females) were randomly sampled from eight local government areas. The prevalence of canine sarcopticosis was found to be 67.45% (259/384) using the ELISA kit. ELISA test had a 96.4% sensitivity against microscopy test (21.42%) as skin scrapping with microscopy demonstrated mites in 12 out of 56 dogs, while ELISA detected antibodies in 54 out of the 56 dogs presented to treatment facilities. A significantly higher seroprevalence was found in the female dogs (P = .019), indigenous dog breeds (P = .01), dogs presented to government facilities for treatment (P = .000), and dogs with active lesions less than the palm of the hand (P = .000). There was no association between the age of dogs and scabies seroprevalence. Skin scrapping still remains ideal and unique in specific mite detection, but its deficiency in sensitivity can best be complimented with the use of a more sensitive ELISA diagnostic kit.

A chitinase-like protein from Sarcoptes scabiei as a candidate anti-mite vaccine that contributes to immune protection in rabbits

BACKGROUND

Scabies is caused by Sarcoptes scabiei burrowing into the stratum corneum of the host's skin and is detrimental to the health of humans and animals. Vaccines are an attractive alternative to replace the acaricides currently used in their control.

METHODS

In the present study, the S. scabiei chitinase-like protein 5 (SsCLP5) was characterized and recombinant SsCLP5 (rSsCLP5) was evaluated as a candidate vaccine protein for anti-mite protection in rabbits. The expression, characterization and immunolocalization of SsCLP5 were examined. Vaccination experiments were performed on three test groups (n = 12 per group) immunized with purified rSsCLP5. Control groups (n = 12 per group) were immunized with PBS, QuilA saponin or empty vector protein. After challenge, the inflammatory reaction and skin lesions were graded and rSsCLP5 indirect ELISA was used to detect antibody IgG levels in serum samples at the time of vaccination and post-challenge.

RESULTS

The results showed that rSsCLP5 had high immunoreactivity and immunogenicity. In S. scabiei, SsCLP5 had a wide distribution in the chewing mouthpart, legs and exoskeleton, especially the outer layer of the exoskeleton. Vaccination with rSsCLP5 resulted in 74.3% (26/35) of rabbits showing no detectable lesions after challenge with S. scabiei.

CONCLUSIONS

Our data demonstrate that rSsCLP5 is a promising candidate for a recombinant protein-based vaccine against S. scabiei. This study also provides a method for studying scabies vaccine using rabbit as an animal model and a basis for screening more effective candidate proteins.

Establishment of infestivity model for Sarcoptes scabiei var canis in Nigerian dogs

Experimental transmission patterns involved with the establishment of mange in dogs were studied to ascertain the effective means of infestation model for mange experiments in dogs. A total of eighteen (18) dogs were used out of which three (3) were naturally infested with Sarcoptes scabie var canis. Five (5) healthy dogs were co-mingled with the three (3) donor dogs for direct contact transmission. Another five (5) mange free dogs were aggregated in a kennel recently vacated by mange infested dogs for environmental and formite transmission while the last five (5) healthy dogs had scrapings from a proximate area of mange lesion sites transferred into the pinnae of each dog for experimental and indirect contact transmission. Successful mite transmission with associated clinical features of pruritus, alopecia, erythema, papules and crusts was achieved with co-mingling of mange naïve and mange infested dogs. These clinical features also differed (p < 0.05) from dogs experimentally infested as this method of transmission was largely unsuccessful. Following the success of the direct contact model closely is the environmental and formite transmission model. Here, healthy dogs were housed in recently vacated mange infested kennels. The direct contact model only differed from the environmental model (p < 0.05) in the expression of erythema and papules in dogs. Although comingling infested and mange naïve dogs guarantees successful direct contact transmission, exposure of healthy dogs to infested facility would also lead to infestation. This study showed that comingling remain an effective means of infestation model for mange experiments in dogs.

Preliminary analysis of Psoroptes ovis transcriptome in different developmental stages

Background

Psoroptic mange is a chronic, refractory, contagious and infectious disease mainly caused by the mange mite Psoroptes ovis, which can infect horses, sheep, buffaloes, rabbits, other domestic animals, deer, wild camels, foxes, minks, lemurs, alpacas, elks and other wild animals. Features of the disease include intense pruritus and dermatitis, depilation and hyperkeratosis, which ultimately result in emaciation or death caused by secondary bacterial infections. The infestation is usually transmitted by close contact between animals. Psoroptic mange is widespread in the world. In this paper, the transcriptome of P. ovis is described following sequencing and analysis of transcripts from samples of larvae (i.e. the Pso_L group) and nymphs and adults (i.e. the Pso_N_A group). The study describes differentially expressed genes (DEGs) and genes encoding allergens, which help understanding the biology of P. ovis and lay foundations for the development of vaccine antigens and drug target screening.

Methods

The transcriptome of P. ovis was assembled and analyzed using bioinformatic tools. The unigenes of P. ovis from each developmental stage and the unigenes differentially between developmental stages were compared with allergen protein sequences contained in the allergen database website to predict potential allergens.

Results

We identified 38,836 unigenes, whose mean length was 825 bp. On the basis of sequence similarity with seven databases, a total of 17,366 unigenes were annotated. A total of 1,316 DEGs were identified, including 496 upregulated and 820 downregulated in the Pso_L group compared with the Pso_N_A group. We predicted 205 allergens genes in the two developmental stages similar to genes from other mites and ticks, of these, 14 were among the upregulated DEGs and 26 among the downregulated DEGs.

Conclusion

This study provides a reference transcriptome of P. ovis in absence of a reference genome. The analysis of DEGs and putative allergen genes may lay the foundation for studies of functional genomics, immunity and gene expression profiles of this parasitic mite species.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1856-z) contains supplementary material, which is available to authorized users.

The acaricidal efficacy of aqueous neem extract and ivermectin against Sarcoptes scabiei var. cuniculi in experimentally infested rabbits

Sarcoptes scabiei var. cuniculi is one of the most important veterinary ectoparasites in rabbits and results in considerable loss of weight, productivity, and wool quality. The acaricidal activity of aqueous leaf extract of neem (CAN) and ivermectin (IVR) were evaluated in vitro and in vivo against S. scabiei var. cuniculi. Rabbits were classified into four groups (ten rabbits each). The first group (group 1) was designated as the negative control group. Each rabbit of the other groups was experimentally infested with 50 mites. One month post-infestation, the second group (group 2) was not treated and taken into account as the positive control group. The third group (group 3) was subcutaneously injected with 1 % IVR (200 μg/kg body weight, three times within a week interval). The fourth group (group 4) was treated topically with CAN (25 %) every 3 days for three consecutive weeks. Index scoring of lesions was described weekly. The number of live mites (larvae, nymphs, and adults) on each rabbit was counted on the 14th, 28th, and 42th day post-treatment (PT). Blood samples were taken 28 and 42 days PT for estimation of some chemical parameters. The body weight and cumulative body weight gain were recoded 14, 28, and 42 days PT. CAN (40 %) was highly efficacious against larvae of S. scabiei var. cuniculi as 100 % mortality was reached 24 h PT. On the other hand, all treated mites with CAN (20 %) and IVR died 48 h PT. The lethal values of CAN (LC50, LC90, LC95, and LC99) were 7.496, 14.67, 17.75, and 25.37 %, respectively, 48 h PT. Lesion scoring in groups 3 and 4 were significantly decreased (P ≤ 0.05), reaching 0.20 and 0.40, respectively, when compared with that of group 2 (4.00), 42 days PT. Twenty-eight days PT, the reduction percentages of mites infesting rabbits were 93.38 and 93.09 % for IVR and CAN, respectively. However, complete mite reduction was reached 42 days PT. Rabbits treated with CAN did not show signs of restlessness or irritation, respiratory signs, or inflammation on the eye and/or skin at the time of application or afterwards. Regarding biochemical analysis, the levels of aspartate aminotransferase, alanine aminotransferase, creatinine, and total cholesterol in rabbits treated with CAN were decreased significantly (P ≤ 0.05) than those of rabbits of the positive control group and those treated with IVR. On the other hand, the levels of total protein, albumin, and globulin of rabbits in group 4 were significantly (P ≤ 0.05) increased when compared with the corresponding values of groups 2 and 3. The body weight and cumulative body weight gain of rabbits treated with CAN were significantly increased (P ≤ 0.05) when compared with such values of groups 2 and 3, 28 and 42 days PT. The present data indicated that CAN had in vitro and in vivo acaricidal efficiency similar to that of IVR and improved the performance of rabbits without inducing adverse effects on treated rabbits; consequently, CAN could be suitable as a promising alternative acaricide for veterinary use.

Characterization and evaluation of a Sarcoptes scabiei allergen as a candidate vaccine

Background

Sarcoptic mange caused by the mite Sarcoptes scabiei is a worldwide disease affecting both humans and animals. Here we report the molecular characterization and evaluation of a recombinant S. scabiei tropomyosin (SsTm) protein in a vaccination trial in rabbits.

Methods

The full-length cDNA was cloned in a bacterial pET vector, and the recombinant protein was expressed in BL21 (DE3) cells and purified. Using specific rabbit antiserum, tropomyosin was localized immunohistochemically in mite tissue sections. Vaccination trials with the recombiant SsTm was carried out in New Zealand rabbits.

Results

The full-length open reading frame (ORF) of the 852 bp cloned gene from S. scabiei encodes a 32.9 kDa protein. The amino acid sequence showed 98.94%, 97.89% and 98.59% homology to Dermatophagoides farina and Dermatophagoides pteronyssinus group 10 allergens and Psoroptes ovis tropomyosin, respectively. Tropomyosin was localized immunohistochemically in mite tissue sections mainly in the mouthparts, legs and integument of the epidermis. The predicted cross-reactivity of SsTm indicated that it is an allergenic protein. While vaccination with the recombiant SsTm resulted in high levels of specific IgG (P < 0.01), a low IgE antibody response and no significant protection against S. scabiei challenge were observed. After challenge, specific IgG levels remained significantly higher than the control (P < 0.01), while changes of total IgE levels were not significant (P > 0.05). However, the lesion areas in the vaccination group decreased at the end of the experiment compared with controls.

Conclusions

Although vaccination with recombinant SsTm did not efficiently control sarcoptic mange in rabbits, the immunogenic properties of tropomyosin suggest it may be developed as a vaccine with alternative adjuvants or delivery methods.

Risk factors for Psoroptes ovis mange on Belgian Blue farms in Northern Belgium

The parasitic mite Psoroptes ovis causes important economic losses in Belgian Blue cattle. Because mange problems vary significantly between farms, a cross-sectional questionnaire survey and subsequent farm visits were performed to identify potential risk factors for P. ovis infections on Belgian Blue farms in Flanders, Belgium. The questionnaire was sent to 1800 beef farms to evaluate the presence and severity of psoroptic mange in the herd and to assess farm management practices, including antiparasitic treatments. Subsequently, about 10% of the farms with a completed questionnaire were visited to validate the questionnaire and to retrieve supplementary information on additional management parameters, such as barn infrastructure and climate. Associations between parasitism and putative risk factors were assessed by logistic regression. Out of 1800 contacted farms, 680 (38%) completed questionnaires were received. Data were collected from 238 barns during 66 farm visits. The questionnaire results demonstrated a high farm prevalence of mange (74%; 95% CI (70.7-77.3)) and half of the farmers declared that the problem was difficult to control. Nevertheless, in only 14% of the barns a high scratching index was recorded and in most of the sampled animals (80%) the affected body surface was less than 10%. This indicates that despite the high prevalence and the difficulty to control the infection, clinical signs were often quite moderate. Logistic regression analyses of the questionnaire and the farm visit data suggested that heavily infested farms treat more intensively against mange. On most farms mange occurred the whole year round and more problems with mange were found on farms where a higher number of animals were purchased per year. In addition, the disease was more prevalent when the animals had a lower hygiene score. This score was strongly correlated with environmental hygiene, indicating that transmission of mites from the environment to the animals should not be underestimated. Conflicting results were obtained on the effect of supplementing minerals on the occurrence of mange. In this study, temperature, light intensity and relative humidity in the barns, ventilation systems, barn infrastructure, animal stocking rate and blood mineral levels were not indicated as risk factors for mange. In conclusion, maintaining a good animal hygiene and if possible, avoiding introduction of cattle may help to control psoroptic mange in Belgian Blue cattle.

Parasite control in calves and growing heifers

Parasite control in calves and growing heifers results in animals that grow faster and remain healthier. Control programs revolve around reducing the parasites (infective stages) in the environment. In confinement, sanitation removes or reduces the number of infective stages (oocysts, cysts, and infective larvae) and the infection rate. On pasture one must resort to pasture management and parasite removal. The mites and lice are generally controlled by reducing or removing the populations on the animals, preventing the spread. Environmental control and manure management impact the fly populations.

Characterisation of recombinant immunoreactive antigens of the scab mite Sarcoptes scabiei

Sarcoptic mange (or scabies) is an important skin disease which can affect a variety of species including humans, cattle, goats, sheep, horses, pigs, rabbits, and dogs. Approximately 300 million people are affected worldwide and in lifestock animals the infestation may lead to substantial economic losses caused by depression in growth and feed conversion rates. Diagnosis of Sarcoptes infestation is difficult and only a few serological tests have been developed using whole mite antigen for diagnosis of mange in animals. Here we describe the isolation and characterisation of cDNAs of several immunoreactive clones and their recombinant expression in Escherichia coli. Three of the proteins contain repetitive sequences which suggests that they might be involved in immune evasion. The application of these antigens in serodiagnosis and the suitability for diagnosis is discussed.

In vivo evidence that Sarcoptes scabiei (Acari: Sarcoptidae) is the source of molecules that modulate splenic gene expression

The clinical signs of a Sarcoptes scabiei (De Geer) (Acari: Sarcoptidae) infestation are initially delayed, which suggests that the mites can depress the immune/inflammatory response. The purpose of this study was to investigate the modulatory properties of scabies mites in vivo at the gene expression level in a secondary lymphoid organ that is involved in initiating an immune response to the parasite. We found that substances from scabies mites influenced the expression of mRNA for molecules that participate in the sequestering of lymphocytes in the periarteriolar lymphoid sheath, primary follicle, and marginal zone of the spleen. Mice exposed to live scabies mites exhibited decreased mRNA expression for the adhesion molecules intercellular adhesion molecule (ICAM)-1, ICAM-2 and L-selectin; the cytokines tumor necrosis factor (TNF)alpha and CCL5; and the receptors for several other cytokines including TNF and interferon gamma. In addition, exposure to live mites or vaccination with a scabies extract resulted in reduced expression of mRNA for B7-2, CD40, CD4, CD8, and CD45, thereby potentially reducing the physical interactions between B cells and T-helper (Th)2 helper cells, between Th1 and Tc cells, and between T-helper cells and antigen-presenting cells, thus depressing their function in response to thymus-dependent antigen. Live scabies mites also depressed expression of toll-like receptors 2, 4, and 6. In conclusion, our results indicate that live mites produce substances that can down-regulate expression of adhesion molecules, cytokines, chemokines, chemokine receptors, and lymphocyte surface molecules involved in leukocyte sequestering and the interaction of B and T cells during activation of an immune response in the spleen.

Sarcoptic mange in three alpacas treated successfully with amitraz

Sarcoptic mange is a serious skin disease in alpacas that can result in high morbidity and even mortality. Three alpacas were presented with sarcoptic mange that had previously failed to respond to repeated topical applications of eprinomectin, and an injection of doramectin. They were moderately to severely pruritic, had extensive lesions of alopecia, erythema, scaling and crusting, and had lost weight. As no drug is currently licensed for the treatment of sarcoptic mange in alpacas in the UK, they were treated with a topical solution of amitraz (50 mL in 10 L) after initial bathing with antibacterial or keratolytic shampoos. The clinical signs completely resolved with no relapse over a 10-month follow-up period. In this small group of alpacas, amitraz was an effective and well-tolerated treatment for sarcoptic mange.

Ectoparasites: Future challenges in a changing world

Ectoparasites are ubiquitous, often highly damaging and in most cases cannot be permanently eradicated; hence, they must usually be managed at a local scale with insecticides or endectocides. However, the growth in resistance, the slow rate of development of new actives, coupled with environmental and health concerns associated with the continued use of some of the existing neurotoxic insecticides, suggest that more sophisticated approaches to their management need to be identified. These approaches need to allow ectoparasite populations to be maintained at acceptable levels, while conserving the compounds that remain available. The development of integrated approaches, in which cascades of management tactics are deployed, with parasiticides available as one component to be used in requisite circumstances, may be the most appropriate route to achieving this aim. An essential element of such an approach is the clear articulation of the purpose of intervention and rational justification of the time-point and manner in which it is attempted. However, for this to be possible, considerably better information is required about the effects of ectoparasite abundance on animal welfare and productivity, in addition to the greater availability of effective alternative control tools. To this end, recent work undertaken at the School of Biological Sciences at the University of Bristol, into the use of biological control agents, off-host trapping and the selective treatment of more highly susceptible individuals or classes of host, is reviewed here.

Problems in diagnosing scabies, a global disease in human and animal populations

Scabies is a worldwide disease and a major public health problem in many developing countries, related primarily to poverty and overcrowding. In remote Aboriginal communities in northern Australia, prevalences of up to 50% among children have been described, despite the availability of effective chemotherapy. Sarcoptic mange is also an important veterinary disease engendering significant morbidity and mortality in wild, domestic, and farmed animals. Scabies is caused by the ectoparasitic mite Sarcoptes scabiei burrowing into the host epidermis. Clinical symptoms include intensely itchy lesions that often are a precursor to secondary bacterial pyoderma, septicemia, and, in humans, poststreptococcal glomerulonephritis. Although diagnosed scabies cases can be successfully treated, the rash of the primary infestation takes 4 to 6 weeks to develop, and thus, transmission to others often occurs prior to therapy. In humans, the symptoms of scabies infestations can mimic other dermatological skin diseases, and traditional tests to diagnose scabies are less than 50% accurate. To aid early identification of disease and thus treatment, a simple, cheap, sensitive, and specific test for routine diagnosis of active scabies is essential. Recent developments leading to the expression and purification of S. scabiei recombinant antigens have identified a number of molecules with diagnostic potential, and current studies include the investigation and assessment of the accuracy of these recombinant proteins in identifying antibodies in individuals with active scabies and in differentiating those with past exposure. Early identification of disease will enable selective treatment of those affected, reduce transmission and the requirement for mass treatment, limit the potential for escalating mite resistance, and provide another means of controlling scabies in populations in areas of endemicity.

Sarcoptic mange and metapodial development in growing male Iberian ibex (Capra pyrenaica)

The effect of mange (Sarcoptes scabiei) on metapodial growth was studied in 24 uninfested and 16 infested male Iberian ibex from Sierra Nevada National Park (southern Spain). Our results show that infested ibex had smaller metatarsal bones, lower body weight, and a delayed rhythm of ossification, by about 1 year. We conclude that skeletal development and body weight in the Iberian ibex are sensitive to sarcoptic mange.

Scabies

Scabies is a neglected parasitic disease that is a major public health problem in many resource-poor regions. It causes substantial morbidity from secondary infections and post-infective complications such as acute post-streptococcal glomerulonephritis. Disease control requires treatment of the affected individual and all people they have been in contact with, but is often hampered by inappropriate or delayed diagnosis, poor treatment compliance, and improper use of topical compounds such as permethrin, lindane, or benzyl benzoate. In addition to concerns over toxicity with such compounds, parasite resistance seems to be increasing. Oral ivermectin is an alternative that has been used successfully in community control programmes. Plant derivatives such as turmeric, neem, and tea tree oil are also promising future treatments. The disease is strongly associated with poverty and overcrowding, and the associated stigma can ostracise affected individuals. Treatment of scabies in poor countries needs to integrate drug treatment programmes with efforts to improve the socioeconomic conditions and education programmes to reduce stigma. We expect the future to bring more sensitive and specific clinical and laboratory-based diagnostic methods, as well as new therapeutic strategies.

Bovine demodicosis: a case report

Tissues samples collected at necropsy from a 9 year-old Holstein cow were fixed in buffered 10% formalin for histological examination. Macroscopic finding did not reveal typical nodular cutaneous lesions. Vulvar microscopic sections of cutaneous tegument showed mites (Demodex bovis), alone and grouped in hair follicles and sebaceous glands.

Chorioptic mange in dairy cattle: treatment with eprinomectin pour-on

A randomized block design study was conducted to confirm the efficacy of topical eprinomectin against naturally acquired Chorioptes bovis mite infestations. Twelve adult Simmentaler Fleckvieh cattle were formed into six replicates of two animals based on pretreatment mite counts. Within replicates, animals were randomly allocated to untreated controls or were treated with eprinomectin 0.5% pour-on solution at 1 mL/10 kg body weight (0.5 mg eprinomectin/kg body weight). Live mites were counted, and mange lesions were scored prior to treatment and at weekly intervals until the end of the study on day 56. Feed consumption was recorded daily throughout the study, and body weights were measured. Differences between variables were declared significant if p < or = 0.05. Mite counts for the cattle treated with eprinomectin were reduced by 100% from day 14 through the end of the study (p < 0.05). At each examination from day 21 through the end of the study, treated animals were significantly clinically improved as measured by lesion scoring compared with untreated controls. Weight gain and feed conversion efficiency were numerically higher in the eprinomectin-treated group. Results of this study demonstrate a positive response in growth rate following effective treatment of cattle for chorioptic mange and underline the economic importance of the parasite and the value of treatment.

Ectoparasites of livestock in Europe and the Mediterranean region

Arthropod ectoparasites can have a major impact on the productivity and welfare of livestock. In recent years, many parts of Europe have seen important changes in the nature of animal husbandry and parasite control, which have increased the need for a precise understanding of the current distribution and prevalence of livestock ectoparasites. In some cases, these changes have been associated with moves towards increased productivity, such as higher-stocking densities, large-scale rearing units, indoor confinement, reduced genetic diversity and large-scale movement of animals and, in others, with a move towards organic farming. There have also been changes in parasite control, associated with the development of new parasiticides, such as the macrocyclic lactones, and concern over the continued use of some of the older neurotoxic compounds. These changes have been exacerbated by outbreaks of endemic disease, the threats of exotic disease introduction and fears of potential changes in arthropod distribution associated with climate change. This paper therefore, reviews the current status of livestock ectoparasites in Europe and the Mediterranean region.

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.