Diagnosis of psoroptic sheep scab with an improved enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of specific antibodies against crude Psoroptes antigen. The diagnostic sensitivity was 93.7% in 191 sheep with clinical signs associated with mange. These animals originated from 29 flocks in which psoroptic mites were detected. All of 59 sheep infested with Psoroptes ovis were seropositive. Additionally, in 49% of 70 clinically unaffected sheep originating from P. ovis-infested flocks, specific antibodies could be detected, suggesting that asymptomatic infestations can be diagnosed by serology. The specificity of the ELISA was 96.5% as determined with 254 sheep originating from 44 flocks without clinical mange. Cross-reactivity in a low range was detected with selected sera of sheep with clinical chorioptic or forage mite infestations. Four sheep seroconverted 2 weeks after experimental P. ovis infestation, i.e. 2 weeks before clinical signs became obvious. After successful doramectin treatment of 14 sheep with naturally acquired P. ovis infestation, the ELISA values declined slowly but remained positive in seven cases beyond 17 weeks.     

Clinical development and serological antibody responses in sheep and rabbits experimentally infested with Psoroptes ovis and Psoroptes cuniculi

Psoroptes ovis of sheep origin, and Psoroptes cuniculi of rabbit origin were used in experimental infestations. In experiment I, groups of four rabbits and four sheep were infested with 50-100 mites of each isolate on the skin of the back (skin infestation, SI) or in the external auditory canal (aural infestation, AI). In rabbits, SI and AI with P. cuniculi and AI with P. ovis induced in all animals typical ear lesions and pronounced antibody reactions to P. cuniculi antigens in ELISA. After SI of rabbits with P. ovis no clinical signs were detected, no mites could be reisolated and no specific antibodies were detected. In sheep, P. ovis SI induced mange whereas AI did not induce typical clinical signs and mites could not be reisolated. In both these animal groups, ELISA revealed pronounced and comparable specific antibody reactions. After SI and AI with P. cuniculi no clinical symptoms were observed and no mites could be reisolated. Nevertheless, low levels of specific antibody were detected. In experiment II, clinical progression and antibody reactions to P. ovis SI in naive sheep were compared with sheep previously exposed to P. ovis or P. cuniculi. In both pre-exposed groups of animals, clinical signs appeared within 2 days after challenge infestation and three days earlier than in primarily infested sheep. Subsequently, no obvious difference in the clinical progression was observed between the three groups of animals. The results of this study document antigenetic crossreactivity of the two morphologically and genetically distinguishable Psoroptes species but differences in their biological behaviour and virulence which both are of epidemiological and taxonomic relevance.     

Use of selamectin for the treatment of psoroptic and sarcoptic mite infestation in rabbits

Selamectin, a novel avermectin compound, was evaluated for its efficacy against naturally occurring infestations of Psoroptes cuniculi and Sarcoptes scabiei. A total of 42 New Zealand rabbits with psoroptic mange and 37 Angora rabbits with sarcoptic mange were used in the present study. On day 0, infested rabbits were treated topically with either selamectin at minimum dose of 6 mg kg(-1) (6-18 mg kg(-1) for New Zealand rabbits, n = 31 and 10-12 mg kg(-1) for Angora rabbits, n = 23) or vehicle only (control groups, n = 11 for New Zealand rabbits, n = 14 for Angora rabbits). The efficacy of selamectin was assessed both clinically and parasitologically by the presence or absence of viable mites. Rabbits were scraped for sarcoptic mites on days 7, 14, 28, 42 and 56 and had otoscopeic and/or microscopic examination for the detection of Psoroptes mites on days 7, 14, 42 and 56. Fisher's exact test was used to assess differences between the vehicle and selamectin treatment in the number of rabbits without mites (cure rates) on each assessment date. It was found that significantly fewer selamectin-treated rabbits had mites detected on skin scrapings (for S. scabiei) or otoscopeic and/or microscopic examination (for P. cuniculi) (P < 0.01) than the vehicle group. Results of the present study suggest that selamectin is effective against naturally infestations of P. cuniculi and S. scabiei in rabbits.     

Field efficacy of flumethrin pour-on against Psoroptes ovis in cattle.

The field efficacy of pour-on formulation of flumethrin 1 per cent was assessed in cattle naturally infested with Psoroptes ovis. In a finishing unit, 18 infested animals were selected, left untreated for one month and examined twice to monitor the progress of the infestation. They were treated twice 10 days apart with a pour-on formulation of flumethrin 1 per cent (2 mg/kg bodyweight). Skin samples were collected from the animals on days 0, 7, 14, 28 and 42 and examined for the presence of live mites. The clinical condition of the cattle was evaluated at the beginning and at the end of the trial using a standardised chart. Bodyweights were recorded on days -32, 0, 28 and 50. In addition the 65 cows in a calving unit were given the same treatment regimen and its efficacy was evaluated on days 0, 7, 14 and 28 in 11 P ovis infested animals. On the day of treatment most of the infested animals had a severe pyodermatitis. From day 7 onwards no live mites were found in the treated animals and there was a marked clinical improvement. The percentage efficacy on day 28 was 100 per cent in both units. In the finishing animals treatment was associated with a marked improvement in daily weight gains between day 0 and day 28.     

Sheep scab control using trans-cinnamic acid

A series of in vitro and in vivo assays were conducted to examine the effects of trans-cinnamic acid ethyl ester on Psoroptes mange mites. In vitro, 24h after exposure to the test material at concentrations of 10, 1 or 0.1% (v/v), 100, 74 and 20% of mites had died, respectively, compared to 8% following exposure to the control (0.05% SDS only). The different life-cycle stages were affected similarly by the test compound. The concentration required to produce 95% mortality 24h after exposure to the test compound was 6.29% (95% confidence interval 4.98-8.88). Tarsal contact of the mites with the test compound was also sufficient to achieve high levels of mortality; 100% death was observed when the mites were placed in contact with either sheep skin circles treated to give 0.01 ml/cm(2) or polyester cloth circles treated with 0.03 ml/cm(2). However, the residual activity of both skin and cloth treated with 0.03 ml/cm(2) was completely lost after 7 days. In vivo, trans-cinnamic acid ethyl ester suspended in 2% (w/v) lecithin was applied as a spray formulation to eight sheep with active artificial infestations of sheep scab. Seven of the 8 treated sheep were cured and remained completely clear of scab mites for 56 days. However, 33 days after treatment 2 adult female mites were observed on one of the eight treated sheep and the mite population on this sheep subsequently recovered. In contrast, in a control group of two infested sheep, treated with a 2% (w/v) lecithin only, mite populations increased as expected in a typical scab infestation, but eventually self-cured in one animal. The data suggest that, with appropriate development of suitable application technology, trans-cinnamic acid ethyl ester could have a role as a potential therapeutic treatment for active sheep scab, however the short residual period of activity is likely to limit its use in commercial sheep flocks.     

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.     

Efficacy of ivermectin against mange and gastrointestinal nematodes of buffalo (Bubalus bubalis)

The incidence of mange in dairy buffalo in India has increased significantly in recent years. The authors record an outbreak of mange affecting a dairy herd stocking about 30,000 buffalo and 1000 cows. The mange mites were either Sarcoptes scabiei or Psoroptes ovis, or a mixed infestation of both. The morbidity rate was 5-30% varying from group to group, with 100% in a severely affected group. Signs noticed were progressive dermatitis, alopecia, keratinization, skin thickened and wrinkled, intense itching and marked loss of condition often ending in death. Great losses of young animals from mange and gastrointestinal nematodes are very common in dairy herds in India. In view of their economic importance, the activity of ivermectin against naturally occurring mange and parasitic infections of adult buffalo and buffalo calves was determined. Ivermectin was administered by subcutaneous injection (IVOMEC 1% w/v - MSD AGVET) at a dose of 200 mcg kg-1 body weight. The efficacy was ascertained from the disappearance of mites from skin scrapings and the reduction in numbers of worm eggs in the faeces. The results of the treatment were dramatic: the mites disappeared within 2 weeks of the drug being administered in the majority of animals, with marked improvement in skin lesions. Four buffalo which had their entire body surface affected with mange needed a second dose on Day 28 for complete recovery. The effect on the nematodes was equally spectacular, with infections of Neoascaris vitulorum, Trichostrongylidae, Oesophagostomum spp. and Bunostomum being eliminated within 1 week of treatment.     

Efficacy of an injectable formulation of eprinomectin against Psoroptes cuniculi, the ear mange mite in rabbits

Thirty rabbits naturally infected with ear mange mite, Psoroptes cuniculi, were subcutaneously administrated with a single dose of eprinomectin at 100, 200 and 300 microg/kg body weight or vehicle on day 0. The extent of lesions was scored on day -6 (prior to treatment), day 0 (treated), days 7, 14, 21, 28 and 35, the ear scabs were collected simultaneously; mites in scabs were examined and counted. The results showed that a single dose of eprinomectin at 200 or 300 microg/kg body weight following subcutaneous administration was able to eliminate P. cuniculi infection in rabbits, and a dose of eprinomectin at 100 microg/kg could significantly reduce mites but was unable to eliminate P. cuniculi.     

Eprinomectin treatment of psoroptic mange in hunter/jumper and dressage horses: a prospective, randomized, double-blinded, placebo-controlled clinical trial

The purpose of this prospective, double-blinded, placebo-controlled clinical trial was to investigate the efficacy of topical eprinomectin for the treatment of psoroptic mange infestation in horses. 24 privately owned hunter/jumper and dressage horses were diagnosed with psoroptic mange infestation based on physical findings and skin scraping results were enrolled and randomly assigned to either topical eprinomectin pour-on solution (at a dose of 500mug/kg body weight weekly once for four applications) treatment group or a placebo group (purified water). Clinical evaluations and skin scrapings were done by the same veterinary investigator at the beginning, during and at the end of the treatment. Both owners and veterinary investigator were blinded to the allocation to the groups. The efficacy of eprinomectin was assessed both clinically and parasitologically by the presence or absence of viable mites. Horses were scraped for psoroptic mites on days 7, 14, 21, 28 and 40 for follow-up. Fisher's exact test was used to assess differences between the eprinomectin treatment and placebo in the number of horses without mites (cure rates) on each assessment date. It was found that significantly fewer eprinomectin treated horses had P. equi mites detected on skin scrapings (p<0.01) than the placebo group. In conclusion, eprinomectin was effective and safe therapy against natural infestations of P. equi in the horses included in this study.     

Treatment and control of sheep scab (Psoroptes ovis) with ivermectin under field conditions in South Africa.

Four trials including 11,266 sheep were conducted in South Africa to evaluate the efficacy of the systemic parasiticide ivermectin against field outbreaks of sheep scab (Psoroptes ovis) when two doses of approximately 200 micrograms/kg were administered subcutaneously seven days apart (days 0 and 7). As sheep scab is a notifiable disease in South Africa, it was not possible to include an untreated control group. The prevalence of clinically affected animals in the four treated flocks varied from 0.4 per cent to 99 per cent before the two treatments. After the treatments, there were no signs of active clinical infection in any of the sheep between days 28 and 30, or at subsequent examinations. P ovis mites were recovered from scrapings from 114 of 127 indicator sheep before the treatment but no mites were recovered from them between days 28 and 30 or 42 and 58 after the treatments.     

Effects of the scab mite Psoroptes ovis on the haematology and live mass of Merino and Dorper sheep

Five Merino and five Dorper sheep were artificially infested with the sheep scab mite Psoroptes ovis and the effect of infestation on their haematology, serum protein levels and live mass recorded for a period of 14 weeks. The reaction of the Merino sheep to infestation was more severe than that of the Dorper sheep. Haematological values fluctuated within the normal range during the assessment period. The mean haemoglobin concentration of the Merino sheep declined until antiparastic treatment was administered 10 weeks after infestation, after which it gradually increased. The lymphocyte counts of both breeds of sheep declined from 2 weeks to 10 weeks post-infestation, but increased after treatment, while the highest eosinophil counts were recorded in the Merino sheep at the height of the acute disease 8-10 weeks post-infestation. Serum albumin values for both breeds and serum globulin values for the Merino sheep were higher than normal during the entire 14-week observation period. A decrease in serum albumin and an increase in serum globulin concentration occurred at the height of infestation in both breeds. The mean live mass of a second group of five infested Merino sheep decreased by 6.4 kg over a 16-week period compared to a gain of 4.56 kg for five infested Dorper sheep.     

5%AVM预防绵羊疥癣病的长效试验

目的检测5%AVM对绵羊疥癣病的预防效果。方法通过痒螨检查确定试验羊,设Ⅰ、Ⅱ、Ⅲ5%AVM三个剂量组,Ⅳ为1%阿维菌素注射液组,Ⅴ为螨净组,Ⅵ为空白对照组,每个组7只试验羊;Ⅶ为传染源组。按羊的体重皮下注射或药浴,观察近90d。结果Ⅰ组61d发病;Ⅱ、Ⅲ组92d发病;Ⅳ组35d发病;Ⅴ组没有发病;Ⅵ组21d发病。结论5%AVM有效预防绵羊疥癣病近90d。     

Efficacy of topical administration of eprinomectin for treatment of ear mite infestation in six rabbits

Six rabbits naturally infested with Psoroptes cuniculi were treated topically on the skin at the base of the neck with 0.5 mg kg(-1) of 0.5% pour-on eprinomectin for cattle, twice at 14-day intervals. Efficacy of the drug was based on the disappearance of clinical signs and the absence of live mites for a period of 6 weeks. Clinical improvement was seen within 3 days of the first application; however, complete recovery of clinical signs and elimination of mites in 5/6 rabbits did not occur until the end of the study. No adverse reactions attributable to eprinomectin treatment were observed during the observation period. Results of this trial indicated that eprinomectin was partially effective in the treatment of psoroptic mange in rabbits.     

Control of cattle mange in southern africa using ivermectin

Seven trials including 768 cattle were conducted in South Africa and Namibia to evaluate the efficacy of the systemic parasiticide ivermectin when administered subcutaneously at a dose rate of 200 micrograms/kg against sarcoptic (Sarcoptes scabiei var. bovis), chorioptic (Chorioptes bovis) and psoroptic (Psoroptes ovis var. bovis) mange mites. The efficacy of a single treatment against Psoroptes and Sarcoptes was greater than against Chorioptes. There was marked clinical cure in all treated cases with loss of crusts and hair regrowth. The number of cases of psoroptic mange in two large herds, of which 42.4% of 724 animals were clinically affected prior to mass treatment, was reduced by 99.3% following a single subcutaneous treatment with ivermectin; a single animal from which mites were recovered may not have been treated. The apparent prevalence and prospects for control and eradication of cattle mange in South Africa and Namibia are discussed.     

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.     

Simulation analysis of the population dynamics of the mite, Psoroptes ovis, infesting sheep.

The pattern of population growth of the ectoparasitic mite, Psoroptes ovis (Acari: Psoroptidae), on its ovine host is considered through the development of a Leslie matrix-based, simulation model. The model is parameterised using experimental data in conjunction with reanalysis of published data. The model shows that on sheep P. ovis populations grow at a rate of approximately 11% per day and the population doubles every 6.3 days. Additional rates of adult mortality, in excess of 50% per day, need to be imposed to prevent population growth. The predictions of the model are tested by comparison of the expected numbers of mites with the numbers recorded in lesions either on naturally infested sheep where the date of infestation can be estimated or on one artificially infested animal, where the initial number of mites and date of infestation are known precisely. In both cases the observed number of mites in lesions relate closely to the numbers expected from the simulations. The model simulations do not support the concept of a 'lag' phase as distinct from the 'growth' phase in the changing pattern of mite abundance on an infested sheep and suggests that the observed pattern of growth is a natural function of an exponential increase in numbers. The development of such models and their use in explaining the demographic processes which drive mite population dynamics are discussed.     

Long-term efficacy of a deltamethrin-impregnated collar for the control of the Australian paralysis tick, Ixodes holocyclus, on dogs

Objective To determine the duration of efficacy of a 4% deltamethrin‐impregnated collar for dogs (Scalibor® ProtectorBand, MSD Animal Health) against adult female paralysis ticks (Ixodes holocyclus). Procedures A controlled pen study was conducted. Dogs were artificially infested at 14‐day intervals with unfed adult female ticks for up to 140 days following application of the collar to the dogs. Efficacy was assessed by manually counting ticks on dogs at 24, 48 and 72 h after each infestation. Results Efficacy at the 72‐h count was 96% after the day 14 tick infestation. The 72‐h efficacy remained above 94% from the day 14 to the day 98 infestations, when efficacy was still 99.5%. Efficacy at 72 h was above 90% after the day 112 infestation and was still 93% at 72 h after the day 140 infestation. Conclusions The deltamethrin‐impregnated collar gave greater than 90% control of paralysis ticks for at least 14 weeks.     

Host preference of the sheep scab mite,Psoroptes ovis

Sheep scab mites, Psoroptes ovis, collected from a Merino donor sheep, were used to infest Merino and Dorper sheep, and Angora and Boer goats. Mites were placed on the sheep on 1 or 2 occasions and on 5 occasions on the goats. All the animals were examined at regular intervals for the presence of scab lesions and living mites. Both sheep breeds developed lesions, but those on the Merino sheep were always larger than those on the Dorper sheep at the same intervals after infestation. None of the goats developed lesions or showed signs of irritation, or harboured any mites.     

Comparative study of doramectin and fipronil in the treatment of equine chorioptic mange

In equids, chorioptic mange is a common dermatitis for which there are no licensed medications in the uk. Doramectin and fipronil are licensed for the control of ectoparasites in other species and were evaluated for the treatment of 17 cases of chorioptic mange in 13 equids. Equids were included if clinical findings were indicative of chorioptic mange, chorioptes mites were positively identified and concurrent disease that could affect response to disease was not evident. A random number table was used to allocate subjects to receive doramectin (group D, eight animals) or fipronil (group F, nine animals). Each of the horses in group D were given 0.3 mg/kg doramectin (Dectomax; Pfizer) on two occasions 14 days apart by subcutaneous injection. All limbs of the horses in group F were sprayed with fipronil 0.25 per cent solution (Frontline; Merial) to the level of the stifles and elbows. Both groups were examined on the day of treatment and 14 and 28 days later to assess the behavioural signs of pruritus and the severity of the dermatological lesions. Acetate tape impressions were collected from the distal limbs and the degree of mite infestation was assessed. By day 28 there were no behavioural signs of chorioptic mange in any of the animals, and there were significant reductions in the numbers of mites in both groups. However, there were no significant reductions in the mean lesion score in either group. There was no significant difference between the effectiveness of the two treatments.     

Amitraz in the control of non-ixodide ectoparasites of livestock

Amitraz has been shown to be successful in controlling mange and lice infestations on pigs which had failed to respond to diazinon and gamma-BHC, respectively, and by the use of a prophylactic programme to maintain pig herds mange free. In addition, trials have indicated the elimination of psoroptic mange from sheep by applying the compound to the animal using either conventional or less conventional methods of treatment. Mixed infections of Chorioptes spp., Psoroptes spp. and Sarcoptes spp., in cattle have also been controlled using spray applications of amitraz, where in some cases organochlorine, organophosphorus and organotin compounds had failed. In a pilot study a heavy infestation of chorioptic mange was controlled on a calf using a pour-on formulation of amitraz.