Performance of the psoroptes ovis - antibody enzyme-linked immunosorbent assay in the face of low-level mite infestation

Psoroptes ovis mites, the causative agent of sheep scab, can severely compromise sheep welfare and production. However, in subclinical infections, mite detection is difficult increasing the risk of spread. A recent serodiagnostic test, based on detecting host antibodies to the P ovis allergen, Pso o 2, has made the detection of subclinical infection possible. The use of this test was demonstrated in subclinical situations, through an opportunistic observational study on an extensive hill farm and a lowland flock with recently introduced, quarantined livestock. Twelve animals were tested from each group. Breeding ewes and lambs on the hill farm had seroprevalences of 16 per cent (12.5–17.8 per cent) and 8.3 per cent (4.8–10.1 per cent), respectively. Quarantined store lambs had a seroprevalence of 16.7 per cent (13.2–18.5 per cent); no evidence of P ovis was found in quarantined replacement ewes. By detecting subclinical infection, this serological test could be a powerful tool in sheep scab control, for quarantine procedures, accreditation programmes, and possibly regional or national eradication protocols

Effect of Air Injection Depth on Big-bubble Formation in Lamellar Keratoplasty: an Ex Vivo Study

This study evaluated the effect of air injection depth in the big-bubble (BB) technique, which is used for corneal tissue preparation in lamellar keratoplasty. The BB technique was performed on ex vivo human corneoscleral buttons using a depth-sensing needle, based on optical coherence tomography (OCT) imaging technology. The needle tip, equipped with a miniaturized OCT depth-sensing probe, was inserted for air injection at a specified depth. Inside the corneal tissue, our needle obtained OCT line profiles, from which residual thickness below the needle tip was measured. Subjects were classified into Groups I, II, III, and IV based on injection depths of 75-80%, 80-85%, 85-90%, and > 90% of the full corneal thickness, respectively. Both Type I and II BBs were produced when the mean residual thicknesses of air injection were 109.7 +/- 38.0 mu m and 52.4 +/- 19.2 mu m, respectively. Type II BB (4/5) was dominant in group IV. Bubble burst occurred in 1/16 cases of type I BB and 3/16 cases of type II BB, respectively. Injection depth was an important factor in determining the types of BBs produced. Deeper air injection could facilitate formation of Type II BBs, with an increased risk of bubble bursts

Eye bank issues: II. Preservation techniques: warm versus cold storage

Most of the tissue used for penetrating keratoplasty is issued through eye banks that store the corneoscleral button either in hypothermic storage at 2–6°C or in organ culture at 31–37°C

Effect of Fibrin Glue on the Biomechanical Properties of Human Descemet's Membrane

10.1371/journal.pone.0037456PLoS ONE75

Preliminary observations on the value of using effective anthelmintic drugs to control nematode parasitism in lambs in the face of a high level of infective larval challenge

Gastrointestinal nematode parasites in small ruminants pose a major challenge to global agriculture. In most cases, their control depends on the availability of anthelmintics, which must be used in a manner that achieves a balance between ensuring adequate productivity and minimising the impact of inevitable selection for drug resistance. In this observational field study, the liveweight gains of lambs grazed on putative heavily infective larval contaminated pasture were compared after effective or ineffective anthelmintic drug treatments. Moxidectin, monepantel, and a derquantel–abamectin combination achieved 100% post treatment efficacies in faecal egg count reduction tests, while the efficacy of levamisole against Teladorsagia circumcincta was only 33%. During the 14 days after treatment, lambs treated with moxidectin, monepantel, and a derquantel–abamectin combination, gained about 0.3 kg, 0.5 kg, and 0.7 kg, respectively, more than those treated with levamisole, generally supporting the economic investment in use of effective drugs. These observations serve to highlight the manner in which effective anthelmintic drugs are used most efficiently with the primary objective of minimising subsequent exposure of naïve lambs to high levels of infective larval challenge, as opposed to the more common practice of simply treating animals grazing on heavily contaminated pastures

A model for the control of psoroptic mange in sheep

No abstract available

Sheep Scab: Assessing the Use of Commercial Diagnostic Data to Enhance Surveillance

Sheep scab is an economically damaging ectoparasitic disease caused by the Psoroptes ovis mite that poses a significant welfare concern for the sheep population in Great Britain (GB). Though sheep scab is endemic, resistance to common treatments has emphasised the importance of timely control. In 2017 a new diagnostic ELISA test for sheep scab was commercialised in GB. Different to the current clinical diagnosis via skin scraping, the sheep scab ELISA reliably detects infestation at the subclinical stage, limiting spread and economic loss. This study collated and analysed data from the sheep scab ELISA since commercialisation to examine its current use, identify risk factors for infestation, and to consider its value as a complementary source of surveillance data. As expected, the number of submissions increased substantially over time, with the highest number received in the last month of the study period (August 2019). The data consistently showed seasonal patterns, with the highest number of submissions in autumn and winter. While spatial analysis showed wide-spread uptake across England and Wales, fewer submissions originated from Scotland, potentially due to its notifiable status in Scotland. The recommended 12-sample submissions for estimation of serostatus at flock level were those most frequently submitted. Interestingly, the majority of submissions originated from itchy sheep, showing the test is also widely used to diagnose sheep with clinical signs. Among the risk factors, double fencing displayed a significant negative association to a positive serostatus submission

Deep Anterior Lamellar Keratoplasty in Eyes With Intrastromal Corneal Ring Segments

PURPOSE: To evaluate the possibility of using the intrastromal corneal ring segments (ICRSs) previously implanted as a depth reference for performing pneumatic dissection in deep anterior lamellar keratoplasty (DALK). METHODS: The depth of placement of 2 symmetrical ICRSs placed in the superior and inferior midperipheral cornea of 4 eyes of 4 patients with keratoconus was measured by means of anterior segment optical coherence tomography. Because of irregular and/or high astigmatism, DALK using pneumatic dissection was performed in all eyes. The standardized procedure included the following: 1) Deep trephination of the recipient cornea outside the ICRSs (9 mm in diameter), aimed at facilitating the insertion and advancement of a dedicated cannula under the ICRS implant, just within its peripheral margin; 2) air injection for pneumatic dissection; 3) removal of about 80% of the anterior stroma; 4) perforation of the "big bubble" ceiling under viscoelastic protection and removal of its central 6 mm; and 5) suturing of a donor lamella of the anterior stroma obtained by microkeratome dissection using a 450-μm head and punched to a diameter of 9 mm. RESULTS: In all cases, the site for air injection was selected where the thickness of the stroma underlying the superior ICRS did not exceed 150 μm. Pneumatic dissection succeeded uneventfully in all eyes; postoperative best spectacle-corrected visual acuity was 20/20 in 3 of 4 eyes, whereas refractive astigmatism was less than 3 diopters in all cases. CONCLUSIONS: The presence of ICRSs facilitates gauging the depth of cannula insertion at the time of DALK, to succeed with pneumatic dissection

Reply

Reply to reader comments of the original article Deep Anterior Lamellar Keratoplasty in Eyes With Intrastromal Corneal Ring Segment