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PubMed1984

Development and transmission of psoroptic mange of cattle in feed lots in endemic and non-endemic regions.

A test was begun in November 1982 to evaluate the development of Psoroptes ovis, the severity of psoroptic mange of cattle, and the incidence of transfer of P. ovis from artificially infested cattle to non-infested cattle held in feed lots in either an endemic (Bushland, TX) or non-endemic region (Kerrville, TX). The 2 herds each consisted of 24 Hereford steers. The 24 steers were randomly assigned to 3 pens of 8 steers per pen. Two steers from each pen that were randomly selected were artificially exposed to ca. 1000 P. ovis (AINF). The development of mange on these 6 AINF steers and the incidence of transfer to the other steers (INF) were monitored approximately every 3 weeks for 17 weeks. The 6 AINF steers at Bushland (endemic region) developed significantly more lesions than the 6 AINF steers at Kerrville. Three AINF steers in Bushland died from hypothermia and mange while no deaths were recorded at Kerrville. The numbers of mites sampled from affected skin areas of AINF steers from both regions were not significantly different. All 18 of the naturally exposed steers (INF) in Bushland contracted mange; whereas, only 9 INF steers in Kerrville did. The severity (% lesions) and number of mites per sample from affected skin were significantly greater on the INF steers in Bushland. These differences among INF steers in Bushland and Kerrville may be attributed to the higher level of parasitism attained in Bushland on the AINF steers. We propose that the extremely cold weather in Bushland contributed to the greater level of parasitism attained on AINF steers in Bushland by stressing the host steers.

Animals↗
PubMed1993

Isolation and partial characterisation of an immunogen from the mite, Psoroptes cuniculi.

The immunological reactions of Psoroptes cuniculi protein components with antigen-specific rabbit antisera and with six plant lectins are described. In immunoblotting, the antisera from rabbits heavily and mildly infested with Psoroptes cuniculi recognized from two to five protein components. Affino-blotting analysis showed that eight mite components were glycoproteins with different types of glycan structures. The immunogenic antigen was isolated by both immunoaffinity chromatography and identified by crossed immunoelectrophoresis. It was a glycoprotein with a relative molecular mass of 48 kDa and with complex or high mannose type of oligosaccharides.

Animals↗
PubMed2003

A physiological and biochemical model for digestion in the ectoparasitic mite, Psoroptes ovis (Acari: Psoroptidae).

Mites are an important group of arthropod pests affecting crops, animals and humans. Despite this, detailed physiological studies on these organisms remain sparse due largely to their small size. Unifying models are required to draw together the diverse information from studies on different groups and species. This paper describes a model for digestion in the parasitic mite, Psoroptes ovis, the causative agent of psoroptic mange or sheep scab disease. The limited information about this species is supplemented with data from other acarines, especially house dust mites and ticks. We review the range of enzymes and allergens found in mites and consider their possible roles in digestion in mites, generally and in particular, P. ovis. Histological studies, enzyme biochemistry and molecular biology and experimental evidence suggest that P. ovis utilises a digestive system reliant upon acid peptidases functioning in a largely intracellular environment. The actions of the digestive enzymes are supplemented by the involvement of bacteria as potential direct and indirect sources of nutrition. It is possible that some extra-corporeal digestion also takes place. The interaction of bacteria and digestive enzymes on the skin surface of the sheep may be responsible for the excessive pathological reactions evident in clinical sheep scab.

Animals↗
PubMed1986

Cross-reactivity between the house dust mite Dermatophagoides pteronyssinus and the mange mites Psoroptes cuniculi and P. ovis. I. Demonstration of antibodies to the house dust mite allergen Dpt 12 in sera from P. cuniculi-infested rabbits.

The cross-reactivity of the mange mites Psoroptes cuniculi (PC) and Psoroptes ovis (PO) antigens with the house dust mite Dermatophagoides pteronyssinus (DP) antigens has been studied. Cross-reactivity between mange mite and house dust mite antigens was demonstrated by both ELISA and immunoelectrophoresis by use of a sheep anti-DP antiserum. Both PC and PO were demonstrated to contain eight cross-reacting antigens. Sera from rabbits infested with PC were demonstrated to produce antibodies to the homologous immunogen, to PO antigens, and to DP antigens. Of the seven sera from infested rabbits tested, four were demonstrated to produce a strong antibody response to a major DP antigen Dpt 12, and two were demonstrated to produce a weak response that was judged empirically by double-diffusion analysis. Two sera were judged to react with the DP lipoprotein, Dpt 4. Sera from control rabbits did not demonstrate reactivity with any extract tested. Despite the detection of anti-Dpt 12 antibodies, however, an antigen corresponding to Dpt 12 was not detected in either PC or PO extracts. The findings that mange mite-infested rabbits produce antibodies that recognize DP antigens probably explain previous observations in which it was demonstrated that commercially obtained rabbit anti-immunoglobulin antisera contain anti-DP antibodies, a finding that suggests caution in the use of such reagents in studies designed to measure antibody responses to DP allergens.

Animals↗
PubMed2000

The use of entomopathogenic fungi for the control of parasitic mites, Psoroptes spp.

In vitro trials were carried out to evaluate the potential of fungal pathogens as biological control agents of parasitic mites, Psoroptes ovis (Hering) (Acari: Psoroptidae) from rabbit hosts (synonym: Psoroptes cuniculi). The fungus Hirsutella thompsonii Fisher showed no pathogenicity. Metarhizium anisopoliae (Metschinkoff), however, showed a high level of pathogenicity; 3 days after exposure to fungal conidia all mites were dead and 6 days after exposure 60% of the dead adult females, 10% of the dead adult males and 30% of the dead female nymphs had fungal hyphae protruding from their cuticular surface. There was a significant effect of conidial concentration on the number of mite cadavers that displayed fungal infection. Exposure to between 1x10(4) and 1x10(6) conidiaml(-1) resulted in 2-25% of the mites being infected. Mean infection levels were highest, 71%, when the mites were exposed to 1x10(7) conidiaml(-1). Similarly, there was a significant effect of conidial concentration on the time taken for the mites to reach 50% levels of mortality (LT(50)) The mean LT(50) value was approximately 2.7 days, when the mites were exposed to a solution of 1x10(7) and 1x10(8) conidiaml(-1) which was significantly shorter than controls exposed to 0.03% Tween-80 solution only. There was no significant effect of passaging the fungus, either once or twice, through the host on the subsequent infectivity of M. anisopliae. The potential for use of entornopathogenic fungi for the control of parasitic mites, particularly in relation to sheep, is discussed.

Animals↗
PubMed2002

Serological cross-sectional survey of psoroptic sheep scab in Switzerland.

Sheep scab, caused by the mite Psoroptes ovis, is a notifiable disease in Switzerland. Mandatory prophylactic treatments are carried out in spring for all sheep grazing on common alpine pastures. Despite these strict control measures the number of outbreaks has been increasing in recent years, raising questions on the spread of this epizootic disease. To improve the traditional microscopic diagnosis, we developed an ELISA for the specific determination of antibodies against psoroptic antigens with sensitivity and specificity of 93.7 and 96.5%, respectively. Using this test, a serum bank, representative of the sheep population in Switzerland (approximately 15% of registered sheep flocks, randomly chosen, collected between February and May 1998), was screened. The prevalence using 16,404 sera was 10.4, and 11.9% of the 2083 flocks were diagnosed as positive. Additionally, there was a significant increase found for mean seropositivity relative to the flock size (P<0.001, linear regression). Therefore, larger flocks had a higher risk of sheep scab, which may be caused by more frequent animal movement. Spatial analysis of the results revealed a region with significantly higher risk (relative risk = 3.5, P<0.001) of seropositivity, where no cases have officially been notified in the period between 1997 and 1999. The next goal is to establish an efficient control strategy based on serological monitoring of the total sheep population.

Animals↗
PubMed1999

Inter- and intra-specific variation within the genus Psoroptes (Acari: Psoroptidae).

In this paper the taxonomy and relative importance of various species within the genus Psoroptes are reviewed with respect to inter- and intra-specific variations in cross infestivity and host specificity, site of infestation and morphological characters. Intra-specific variation within populations of the sheep scab mite, Psoroptes ovis will then be discussed critically with respect to virulence (the relative growth of the scab lesion and mite burdens), epidemiology, susceptibility to the systemic acaricide, ivermectin, and resistance to synthetic pyrethroid and organophosphate acaricides. Finally, it is suggested that the ear mite, P. cuniculi, and the sheep scab mite, P. ovis are variants of the same species. Information was collected from published literature and from the results of unpublished studies carried out at the VLA, Weybridge over the last 10 years.

Animals↗
PubMed1999

A review of the use of a controlled-release formulation of ivermectin in the treatment and prophylaxis of Psoroptes ovis infestations in sheep.

The options for the treatment and control of sheep scab (psoroptic mange) have been increased in recent years through the introduction of the endectocides ivermectin, doramectin and moxidectin. Whilst therapeutic efficacy is good, the current injectable formulations offer limited protection against re-infestation with Psoroptes ovis. An intraruminal controlled-release formulation of ivermectin has been developed to provide therapeutic and prophylactic activity against a range of sensitive endo- and ecto-parasites of sheep for 100 days after administration. These ivermectin boluses are designed to release ivermectin at 20-40 microg/kg/day over 100 days and were developed for use in sheep of 20-90 kg bodyweight. Several controlled therapeutic and prophylactic trials against sheep scab have been conducted under a variety of protocols with such boluses in Europe and South America. The results of these studies indicate that the bolus provides 100% therapeutic efficacy against established P. ovis infestations and equivalent prophylactic efficacy against challenge infestations administered during the active life of the bolus.

Animals↗
PubMed2000

Species of the genus Psoroptes (Acari: Psoroptidae): a taxonomic consideration.

The biosystematic status of mite species belonging to the genus Psoroptes Gervais, 1841 is difficult to determine by phenotypic methods and has been subject to taxonomic revisions and ongoing debate. At present, the existence of five species, P cuniculi (Delafond, 1859), P. ovis (Hering, 1838). P. equi (Hering, 1838), P. cervinus Ward, 1915 and P. natalensis Hirst, 1919, is generally accepted. This classification is based mainly on the host species, the localization of the mites on their hosts and morphological characters of male mites. However, a critical review of the literature indicates that the features used to discriminate between the five species are not unequivocal: (a) the localization of mite populations on host animals is not completely strict, (b) the lengths of the outer opisthosomal setae of male mites, which are the main morphological features used for species discrimination, overlap between the five postulated species, and (c) host specificity cannot be deduced from results of transfer experiments. Rather, conspecificity of the members of the genus Psoroptes has to be presumed which is supported by molecular genetic analyses. On these grounds and on rules of priority P. cervinus Ward, 1915, P. cuniculi (Delafond, 1859), P. natalensis Hirst, 1919 and P. ovis (Hering, 1838) are seen as synonyms of P. equi (Hering, 1838).

Animals↗
PubMed2000

Life-cycle stage morphology of Psoroptes mange mites.

Detailed life-cycle stage descriptions for the ectoparasitic mite Psoroptes ovis (Hering) (Acari: Psoroptidae) from rabbit hosts (syn. Psoroptes cuniculi) are presented. The results resolve a number of contradictions in the literature relating to the recognition of the life cycle stages of these mites. This study supports the view that there are two distinct male nymphal stages, both lacking dorsoposterior tubercles. The male tritonymph is significantly larger than the protonymph and has five pairs of metapodosomal setae rather than three. In addition, male tritonymphs have two pairs of cuticular pits on the central metapodosoma rather than the single pair of the protonymph. The results also show that the female protonymph can be distinguished from the male nymphal stages and the female tritonymph. Both female nymphal stages possess dorsoposterior tubercles, but the protonymph is significantly smaller than the tritonymph. In addition, the protonymph possesses three pairs of metapodosomal setae rather than five, one pair of cuticular pits rather than two, and a pulvillus on leg IV which is absent in the female tritonymph. The presence of dorsoposterior tubercles enables the female nymphs to be distinguished easily from the males. By contrast, distinguishing between the nymphal stages of the same sex relies on the identification of both the number of metapodosomal setae and cuticular pits. These descriptions are used to produce a key, which allows the various stages of both sexes to be distinguished.

Animals↗
PubMed1989

Observations on the potential for natural transfer of Psoroptes cuniculi and Chorioptes bovis (Acari: Psoroptidae) between goats and sheep.

Goats and sheep were pastured together and held in close contact in yards twice a month for 21 months. The goats had a high prevalence of both the rabbit ear canker mite, Psoroptes cuniculi and the chorioptic mange mite, Chorioptes bovis. The sheep were not infested with P. cuniculi at the beginning of the study and viable C. bovis could not be detected. At no time during the study did P. cuniculi establish in the ears of sheep, despite a maximum prevalence of >95% P. cuniculi in goats. This may have been related to the viscous nature of sheep cerumen. Levels of cerumen in goats' ears increased with increasing prevalence of the mite in the flock. The prevalence of C. bovis in the sheep flock did not exceed 10%, despite a maximum prevalence of >90% infested goats. The difficulty of detecting light infestations of mites means that it was not clear whether the C. bovis infestation of sheep was derived from goats or was present when the study began. Whatever the source, close contact with goats with an active and extensive C. bovis infestation seems unlikely to seriously influence populations of the ectoparasite in sheep. Psoroptes cuniculi was found to he established in goats as young as five days and post-mortem examination of goats' ears was more successful at revealing P. cuniculi than was use of an otoscope during life.

Journal Article↗
PubMedDate not supplied

Identification of tropomyosin, paramyosin and apolipophorin/vitellogenin as three major allergens of the sheep scab mite, Psoroptes ovis.

Analysis by one-dimensional (1-D) SDS-PAGE/Western blotting of whole mite extract (larval and adult stages) with sheep sera taken 0-84 days after infection with the sheep scab mite, Psoroptes ovis revealed a progressive IgE antibody response, with a dominant high molecular weight allergen (MW 180 kDa) detected early during infection. Further analysis by two-dimensional (2-D) SDS-PAGE/Western blotting with post-infection sera, revealed a more complex picture with numerous (> 20) IgE reactive spots. Trypsin digest and Maldi-ToF analyses of these spots identified two house dust mite allergen homologues, namely tropomyosin (Der p 10) and paramyosin (Der p 11), and analysis of a third spot indicated an apolipoprotein-like IgE reactive protein (Der p 14). Further 1-D and 2-D SDS/Western blotting, with specific antibodies to the house dust mite allergens Der p 10, 11, and to the IgE reactive peptide of the high molecular weight house dust mite allergen, Der p 14 (vitellogenin/apolipophorin), provided firm evidence for the presence of these three allergens in extracts of the Psoroptes mite. These studies show for the first time that homologues of the house dust mite 10, 11 and 14 group allergens are represented as immunodominant allergens of the sheep scab mite, and may represent important vaccine candidates.

Allergens↗
PubMed2005

Morphological and molecular comparison of host-derived populations of parasitic Psoroptes mites.

Infestation by parasitic Psoroptes mites (Acari: Psoroptidae) is an important cause of economic loss and welfare problems in livestock in many areas of the world. At least five species within this genus have been recognized, based on the host infested, the infestation site and differences in length of the opisthosomal setae of adult male mites. Here the integrity of these species is considered by subjecting populations of mites from a range of host species and geographical locations to simultaneous morphological and molecular genetic analyses. Morphological analysis showed that there were significant differences in shape and size between mite populations from different hosts, and that length of the outer opisthosomal setae in males and the homologous seta in females were the most important distinguishing character in adults. However, considerable variation in outer opisthosomal seta length was evident within and between populations of mites, and differences were not clearly related to host-species or geographical origin and did not support the accepted species differences. Molecular characterization using sequence data from the mitochondrial second internal transcribed spacer (ITS-2) region and microsatellite markers found little or no consistent host-related variation between the mite population samples. The results suggest that there is no case for considering the Psoroptes mites from the different hosts examined as separate species and that the morphological variation observed therefore may represent phenotypic adaptation to the local microenvironment on particular species of host.

Animal Structures↗
PubMed2006

In vitro tests for evaluation of the hatchability of the eggs of Psoroptes mites following exposure to acaricidal compounds.

Three in vitro assays for the evaluation of the hatchability of the eggs of the mite Psoroptes ovis (Hering) (Acari: Psoroptidae) are described. Preliminary trials showed that hatching occurs at very high rates when eggs are incubated under conditions of high humidity, on a liquid medium and in agarose dishes. These three protocols were compared, taking into account the ease of preparation, follow-up and accuracy of counting. The best protocol was found to be the use of agarose dishes. It was accurate, easy to carry out and reproducible for further evaluation of existing or potentially new compounds against both adults and eggs of Psoroptes spp. The acaricidal properties of phoxim and amitraz were then evaluated against eggs and adults using the three protocols. Results showed that for both drugs, in vitro adulticidal activity was complete, whereas the in vitro ovicidal activity was only partial. Nevertheless, efficacy of amitraz against both adults and eggs was shown to be higher than that of phoxim.

Animals↗
PubMed1987

Hematology in the regressive phase of bovine psoroptic scabies.

Hereford calves were infested with Psoroptes ovis. Hemograms were evaluated weekly for 7 weeks during progressively extensive dermatitis and compared to uninfested control calves. Calves were treated with ivermectin and weekly hemograms were compared for 4 weeks during regression of clinical disease. They developed extensive dermatitis and marked decreases in total white blood cells, neutrophils, and lymphocytes. Infested calves also had moderate anemia, increased plasma proteins, and increased plasma fibrinogen. Some calves developed marked eosinophilia. Within 1 week after ivermectin treatment, nearly all hematologic parameters returned or began to return to normal values, even though scabs remained on the calves at 4 weeks. Peak eosinophilia in calves which responded occurred 1 to 2 weeks after treatment. The findings indicate that most of the hematologic changes occurring with psoroptic scabies in cattle are associated with living mites and not with toxic substances in the scab on the skin surface.

Animals↗
PubMed1980

Psoroptic scabies in bignorn sheep (Ovis canadensis mexicana) in New Mexico.

Prior to 1978, no reports were made of scabies lesions or mites recovered from any Mexican bighorn sheep (Ovis canadensis mexicana) examined in the San Andres National Wildlife Refuge in southern New Mexico. In 1978, all of five rams harvested by hunters had live mites of the genus Psoroptes and active lesions of scabies in their ears and/or on their bodies. Deaths due to scabies were not documented during this outbreak although aerial helicopter surveys conducted in March, June and September, 1979 recorded less than half the sheep observations of five previous and similarly conducted surveys. After measurement of the length of the outer opisthosomal setae of the male mites, they appear to be Psoroptes ovis (Hering), the common scabies mite of domestic sheep, cattle and horses. Final specific determination must await proposed transmission studies with domestic livestock.

Animals↗
PubMed1989

Can androgen deficiency promote an outbreak of psoroptic mange mites in male deer?

Repeated outbreaks of infection by psoroptic mange mites (Psoroptes equi var. ovis) affecting most regions of the body and legs were observed in several male white-tailed deer (Odocoileus virginianus) suffering from hypoandrogenism (e.g., castrates, animals treated with antiandrogens or postprime). The massive infection was characterized by a severe alopecia and skin inflammation and began usually in early winter. One or two spray treatments of a 1% solution of Lindane was usually sufficient to eliminate the clinical signs of the disease and to restore a healthy hair coat. Neither healthy male or female deer have ever exhibited any external signs of this disease nor has the parasite been detected in the scrapings of their skin. We propose a possible relationship between the hormonal status of these animals and their resistance to this parasitic mite infection.

Androgens↗
PubMed1990

Psoroptic scabies in Rocky Mountain bighorn sheep (Ovis canadensis canadensis) from Wyoming.

Thirteen Rocky Mountain bighorn sheep (Ovis canadensis canadensis) with clinical signs of psoroptic scabies were captured in Wyoming. Signs included droopy ears, depilation on the head and neck, and exudate in the ears. Mites were identified as either Psoroptes cervinus or P. equi. Two ewes with scabies at the time of original capture had no clinical signs of mite infection 1 and 2 yr later.

Animals↗