Virulence-associated protein characterisation of Rhodococcus equi isolated from bovine lymph nodes

Rhodococcus equi has a low pathogenicity in cattle, but it occasionally causes lymph node granulomas, which are detected at abattoir post mortem inspection, and must be distinguished from tuberculous granulomas. Lymph node lesions were detected in 6719 cattle, from a total of 3,263,622 cattle examined post mortem in abattoirs, in the Republic of Ireland, during 1997 and 1998. Histological examination was performed on all lesions, principally for the purpose of identifying animals with tuberculosis. A total of 1122 of the lesions were cultured on blood agar and on Stonebrinks and Lowenstein-Jensen medium containing pyruvate, because the histological findings were difficult to interpret or were suggestive of R. equi infection. R. equi was isolated from 264 lesions. Almost all of the R. equi granulomas were confined to a single lymph node, and were present predominantly in the retropharyngeal, bronchial and mediastinal lymph nodes. R. equi granulomas were present in a significantly higher proportion of the lesions detected in steers and heifers compared to cows. The prevalence in the total population of 3.3 million cattle examined post mortem was 0.008%. The 15-17kDa antigens, associated with virulence in this organism, and the 20kDa antigen, associated with intermediate virulence, were not detected in isolates from 146 cattle, analysed by immunoblot assays. A PCR assay to detect the plasmid gene encoding the 15-17kDa antigens was also negative for isolates from these 146 animals. Plasmids were not detected in 30 isolates which were examined.     

Understanding the public health impacts of farm vehicle public road crashes in North Carolina

Discussions with groups of North Carolina farmers identified farm vehicle public road safety as their primary occupational health and safety concern. Findings of a mail survey of North Carolina growers participating in a North Carolina Department of Labor migrant housing inspection program indicated that over 97% of them felt less safe on North Carolina public roads now (1999) than five years prior (1995), and over 79% currently (1999) felt unsafe transporting farm vehicles on North Carolina public roads. Using both primary and secondary data, we explore the context of farm vehicle public road crashes, identify contributing individual and environmental risk factors, and estimate the public health cost. Recommendations and suggestions for future farm vehicle public road safety research and interventions are proposed.     

Using latent class analysis to estimate the test characteristics of the γ-interferon test, the single intradermal comparative tuberculin test and a multiplex immunoassay under Irish conditions

Considerable effort has been devoted to improving the existing diagnostic tests for bovine tuberculosis (single intradermal comparative tuberculin test [SICTT] and γ-interferon assay [γ-IFN]) and to develop new tests. Previously, the diagnostic characteristics (sensitivity, specificity) have been estimated in populations with defined infection status. However, these approaches can be problematic as there may be few herds in Ireland where freedom from infection is guaranteed. We used latent class models to estimate the diagnostic characteristics of existing (SICTT and γ-IFN) and new (multiplex immunoassay [Enferplex-TB]) diagnostic tests under Irish field conditions where true disease status was unknown. The study population consisted of herds recruited in areas with no known TB problems (2197 animals) and herds experiencing a confirmed TB breakdown (2740 animals). A Bayesian model was developed, allowing for dependence between SICTT and γ-IFN, while assuming independence from the Enferplex-TB test. Different test interpretations were used for the analysis: SICTT (standard and severe interpretation), γ-IFN (a single interpretation), and a range of interpretations for the Enferplex-TB (level-1 [high sensitivity interpretation] to level-5 [high specificity interpretation]). The sensitivity and specificity (95% posterior credibility intervals; 95% PCI) of SICTT[standard] relative to Enferplex-TB[level-1] and γ-IFN were 52.9-60.8% and 99.2-99.8%, respectively. Equivalent estimates for γ-IFN relative to Enferplex-TB[level-1] and SICTT were 63.1-70.1% and 86.8-89.4%, respectively. Sensitivity of Enferplex-TB[level-1] (95% PCI: 64.8-71.9%) was superior to the SICTT[standard], and specificity of the Enferplex-TB[level-5] was superior to γ-IFN (95% PCI: 99.6-100.0%). These results provide robust measures of sensitivity and specificity under field conditions in Ireland and suggest that the Enferplex-TB test has the potential to improve on current diagnostics for TB infection in cattle. The extent of that potential will be assessed in further studies.     

Application of the Enfer chemiluminescent multiplex ELISA system for the detection of Mycobacterium bovis infection in goats

A study was conducted to optimise a multiplex serological immunoassay for use in identification of goats infected with Mycobacterium bovis. To assess assay specificity, 31 goats with a history of being free from M. bovis infection were used. To determine assay sensitivity, 180 Single Intradermal Comparative Tuberculin test (SICTT) positive goats were recruited. Additionally, 286 SICTT negative goats classed as potentially exposed animals present in the same positive herds were also included in the study. The results of the assay demonstrated a specificity of 100%. The multiplex assay detected 57/60 SICTT (95.0%) positive animals in one M. bovis infected herd and 120/120 (100%) in a second herd. In a separate experiment, 28 M. caprae culture confirmed infected goats from Spain were assayed, of which 24 (85.7%) were found positive in the test. The results show that inclusion of an antibody based assay can improve the ability to identify M. bovis and M. caprae infected goats. With further development and validation the multiplex assay may prove to be a useful tool for control of M. bovis and M. caprae infection in goats.     

Calcium channel blocker toxicity

Objective: Calcium channel blockers (CCB) are frequently prescribed for veterinary patients and the incidence of toxicosis secondary to these agents is increasing. The purpose of this review is to discuss toxicity of these agents and review therapeutic options. Etiology: Calcium plays a vital role in maintaining cellular functions within the cardiovascular system. Toxicosis secondary to these drugs can have deleterious effects on vascular tone, cardiac contractility, as well as electrical conduction in the heart. Diagnosis: The intitial diagnosis is often made based on history of ingestion, physical examination and electrocardiography. Definitive diagnosis of CCB overdose can be made via quantification of serum concentrations of the drug ingested. Therapy: Initial therapy should consist of inducing emesis and administration of activated charcoal. Other potential therapies include intravenous calcium, parasympatholytics, sympathomimetics, glucagon, insulin and dextrose, placement of a temporary pacemaker, or calcium channel agonists. Prognosis: There is little data on the outcome of CCB toxicosis. Aggressive management of these cases is necessary to try and minimize morbidity and mortality.     

Microtubules in spermatozoa of childia (turbellaria, acoela) revealed by negative staining

Many intact axial units, with attached basal plates, are found in spermatozoa of Childia groenlandica negatively stained with phosphotungstic acid. Electron micrographs show a total of nine doublet microtubules, confirming observations on sectioned material, where nine peripheral doublets, but no single central ones, occurred. Living spermatozoa move by waves progressing along a double undulating membrane.     

Quantification of the relative efficiency of factory surveillance in the disclosure of tuberculosis lesions in attested Irish cattle

In Ireland, factory surveillance of cattle for gross lesions is an important supplementary method for detecting herds infected with bovine tuberculosis (tb), and in recent years between 27 and 46 per cent of all new herd breakdowns in any year have been detected by this method. The aim of this study was to determine the relative efficiency of factories in detecting lesions among attested cattle slaughtered during 2003 and 2004. National databases were available on animal slaughter, programmes of tuberculin testing for bovine tb and laboratory confirmation of suspected lesions. Factories were ranked according to their submission risk (number of animals submitted with lesions/number of attested animals killed) and confirmation risk (number of animals with laboratory-confirmed lesions/number of animals submitted with lesions), adjusting for the risk profile of the animals slaughtered, including potential confounding factors such as their age and sex, whether they were purchased or homebred, the test history of their herd, the prevalence of bovine tb in the area and the season of slaughter. Approximately 3.7 million cattle were slaughtered in 42 Irish export-licensed factories during the two years. Complete data were available for 2,374,987 animals from 84,510 attested herds in 2845 District Electoral Divisions. Samples from 7398 animals with suspected tb lesions were submitted for laboratory examination; 4767 (64.4 per cent) were positive, 2011 were negative and 620 were inconclusive. The average unadjusted submission risk for all the factories was 22 per 10,000, ranging from 0 to 58 per 10,000. The unadjusted factory confirmation risk (excluding factories that had sent in fewer than 10 lesions) varied between 34.3 per cent and 86.3 per cent. The unadjusted and adjusted submission and confirmation risks were highly correlated, and animal-related factors (including their characteristics and origin) therefore did not contribute to the variations in factory-level submission and confirmation risks.     

Clinical management of superficial complicated corneal ulcerations infected with newly identified fastidious bacteria with unknown antibiotic sensitivity in three horses

This case series addresses a clinical approach to a specific type of infected corneal ulceration in horses; the slow-healing superficial complicated corneal ulceration involving a fastidious or possibly newly identified bacteria for which no antibiotic sensitivity can be determined. These corneal ulcerations present as superficial, nonhealing lesions that appear infected based on cellular infiltration of the cornea. Because they are superficial, they do not appear to be as serious to the referral veterinarian as deep stromal corneal ulcerations. However, superficial corneal ulcerations are complicated and slow healing, ultimately frustrating both owners and primary care clinicians. Culture results are often negative, or implicate a newly identified bacteria with no known antimicrobial sensitivity in horses.     

A model to assess trade-offs between environmental impact and profitability of offshore salmon farms: A case study on Chile

ABSTRACT

In recent decades, aquaculture has emerged as a viable method to help supply the growing global demand for seafood; however, expansion of the industry comes with potential negative impacts. Regulatory decisions governing aspects like aquaculture farming practices and farm siting inherently lead to trade-offs between profitability and the health of the surrounding environment through impacts including pollution, disease, and disturbance from escaped fish. Efficiently and sustainably scaling up aquaculture will require the development of methods for explicitly examining the trade-offs among these impacts and socioeconomic objectives. We developed a model to assess these trade-offs and illustrate the approach with a case study of salmon aquaculture in southern Chile. In the case study we found evidence that all 21 farms with approved permits may be underperforming on both profitability and the protection of ecosystem health. Our model suggests that explicit evaluation of trade-offs can illuminate the potential for improvements on multiple outcomes simultaneously.