Reducing the future threat from (liver) fluke: realistic prospect or quixotic fantasy?

The liver fluke remains an economically significant parasite of livestock and is emerging as an important zoonotic infection of humans. The incidence of the disease has increased in the last few years, as a possible consequence of changes to the World's climate. Future predictions suggest that this trend is likely to continue. Allied to the changing pattern of disease, reports of resistance to triclabendazole (TCBZ) have appeared in the literature, although they do not all represent genuine cases of resistance. Nevertheless, any reports of resistance are a concern, because triclabendazole is the only drug that has high activity against the migratory and damaging juvenile stages of infection. How to deal with the twin problems (of increasing incidence and drug resistance) is the overall theme of the session on “Trematodes: Fasciola hepatica epidemiology and control” and of this review to introduce the session.

Greater knowledge of fluke epidemiology and population genetics will highlight those regions where surveillance is most required and indicate how quickly resistant populations of fluke may arise. Models of disease risk are becoming increasingly sophisticated and precise, with more refined data analysis programmes and Geographic Information Systems (GIS) data. Recent improvements have been made in our understanding of the action of triclabendazole and the ways in which flukes have become resistant to it. While microtubules are the most likely target for drug action, tubulin mutations do not seem to be involved in the resistance mechanism. Rather, upregulation of drug uptake and metabolism processes appear to be more important and the data relating to them will be discussed. The information may help in the design of new treatment strategies or pinpoint potential molecular markers for monitoring fluke populations. Advances in the identification of novel targets for drugs and vaccines will be made by the various “-omics” technologies that are now being applied to Fasciola. A major area of concern in the current control of fasciolosis is the lack of reliable tests for the diagnosis of drug (TCBZ) resistance. This has led to inaccurate reports of resistance, which is hindering successful disease management, as farmers may be encouraged to switch to less effective drugs. Progress with the development of a number of new diagnostic tests will be reviewed.

The effect of increasing dietary fibre and the provision of straw racks on the welfare of sows housed in small static groups

This study assessed the effects of increasing dietary fibre levels in concentrate rations and providing access to straw in racks on the welfare of pregnant sows housed in small static groups. In a 2 x 2 factorial design experiment, 128 Large White x Landrace pregnant sows were offered one of two diets: (i) High fibre diet with 9% crude fibre, or (ii) Control diet with 4.5% CF, and one of two levels of access to a foraging substrate: (i) access to straw in racks or (ii) no straw. The study was replicated eight times using groups of four sows, and treatment periods lasted four weeks. Sows were housed in pens with voluntary cubicles and a slatted exercise area and were offered a wet diet twice a day. Back-fat levels were measured before sows were mixed into groups at 28 days post partum, and four weeks later. Aggressive interactions were recorded on the day of mixing, and injury scores were recorded one week post mixing. Scan sampling was used to collect data on general activity, posture and location of the sows, and on sham-chewing and bar-biting behaviours across the treatment period. In addition, detailed focal observations were carried out on all sows across the treatment period. Straw usage was also recorded. There were no treatment effects on changes in back-fat levels over the treatment period. Treatments had no effect on post-mixing aggression or on injury scores. However, focal observations showed that sows with access to straw were involved in fewer bouts of head-thrusting over the treatment period. Control diet sows spent more time inactive than sows on the high fibre diet, however high fibre diet sows spent more time lying with eyes closed than sows on the control diet. Sows on the high fibre diet with access to straw showed less sham-chewing and bar-biting behaviour than sows in other treatments. These results show that although a diet containing 9% crude fibre promoted resting behaviour, it was necessary to combine it with access to straw to reduce stereotypic behaviour of sows in small static groups.

Evaluation of an immunobiosensor for the on-site testing of veterinary drug residues at an abattoir. Screening for sulfamethazine in pigs

A study was conducted to determine the feasibility of performing

Development and validation of a method for the confirmation of nicarbazin in chicken liver and eggs using LC-electrospray MS-MS according to the revised EU criteria for veterinary drug residue analysis

A method is described for the quantitative confirmation of 4,4'-dinitrocarbanilide (DNC), the marker residue for nicarbazin in chicken liver and eggs. The method is based on LC coupled to negative ion electrospray MS-MS of tissue extracts prepared by liquid-liquid extraction. The [M-H](-) ion at m/z 301 is monitored along with two transition ions at m/z 137 and 107 for DNC and the [M-H](-) ion at m/z 309 for the internal standard, d(8)-DNC. The method has been validated according to the new EU criteria for the analysis of veterinary drug residues at 100, 200 and 300 mug kg(-1) in liver and at 10, 30 and 100 mug kg(-1) in eggs. Difficulties concerning the application of the new analytical limits, namely the decision limit (CC) and the detection capability (CC) to the determination of DNC in both liver and eggs are discussed.

Applied aspects of Rhodococcus genetics

Eubacteria of the genus Rhodococcus are a diverse group of microorganisms commonly found in many environmental niches from soils to seawaters and as plant and animal pathogens. They exhibit a remarkable ability to degrade many organic compounds and their economic importance is becoming increasingly apparent. Although their genetic organisation is still far from understood, there have been many advances in recent years. Reviewed here is the current knowledge of rhodococci relating to gene transfer, recombination, plasmid replication and functions, cloning vectors and reporter genes, gene expression and its control, bacteriophages, insertion sequences and genomic rearrangements. Further fundamental studies of Rhodococcus genetics and the application of genetic techniques to the these bacteria will be needed for their continued biotechnological exploitation.

Pathogenicity and molecular genetics of O-specific side-chain lipopolysaccharides of Escherichia coli

Lipopolysaccharide (LPS), a glycolipid molecule found on the outer leaflet of outer membranes of gram-negative bacteria, consists of three moieties: lipid A, core oligosaccharide, and the O-specific polysaccharide chain. The O-specific side chain, which extends to the extracellular milieu, plays an important role in pathogenicity, especially during the initial stages of infection, because of its ability to interact with serum complement. In recent years, several laboratories have used recombinant DNA tools to determine, at the molecular level, the organization, expression, and regulation of genes involved in LPS biosynthesis in Salmonella and Escherichia coli. An increased understanding of the molecular aspects of the O-specific side-chain genes will shed light on the intimate details related with the formation of the O-specific side chain, its assembly onto the lipid A--core, and the translocation and insertion of the complete LPS molecule into the outer membrane. It will also contribute to the understanding of the evolution of these genes and the correlation of chemical diversity of O-specific side chains with the genetic diversity of O-specific side-chain genes. In addition, since the O-specific side chains are involved in the pathogenicity of medically important gram-negative bacteria, a basic understanding of the regulation and expression of O-specific side chain LPS genes will contribute to the field of molecular pathogenesis. This article provides an overview of the role of O-specific side chains in septicemic infections and also discusses the current status of molecular genetic studies on O-specific side-chain genes from E. coli.

Optimizing the balance between false positive and false negative error probabilities of confirmatory methods for the detection of veterinary drug residues

GC-MS data on veterinary drug residues in bovine urine are used for controlling the illegal practice of fattening cattle. According to current detection criteria, peak patterns of preferably four ions should agree within 10 or 20% from a corresponding standard pattern. These criteria are rigid, rather arbitrary and do not match daily practice. A new model, based on multivariate modeling of log peak abundance ratios, provides a theoretical basis for the identification of analytes and optimizes the balance between the avoidance of false positives and false negatives. The performance of the model is demonstrated on data provided by five laboratories, each supplying GC-MS measurements on the detection of clenbuterol, dienestrol and 19 beta-nortestosterone in urine. The proposed model shows a better performance than confirmation by using the current criteria and provides a statistical basis for inspection criteria in terms of error probabilities.

Stability during cooking of anthelmintic veterinary drug residues in beef

Anthelmintic drugs are widely used for treatment of parasitic worms in livestock, but little is known about the stability of their residues in food under conventional cooking conditions. As part of the European Commissionfunded research project ProSafeBeef, cattle were medicated with commercially available anthelmintic preparations, comprising 11 active ingredients (corresponding to 21 marker residues). Incurred meat and liver were cooked by roasting (40 min at 190°C) or shallow frying (muscle 8-12 min, liver 14-19 min) in a domestic kitchen. Raw and cooked tissues and expressed juices were analysed using a novel multi-residue dispersive solid-phase extraction method (QuEChERS) coupled with ultra-performance liquid chromatography-tandem mass spectrometry. After correction for sample weight changes during cooking, no major losses were observed for residues of oxyclozanide, clorsulon, closantel, ivermectin, albendazole, mebendazole or fenbendazole. However, significant losses were observed for nitroxynil (78% in fried muscle, 96% in roast muscle), levamisole (11% in fried muscle, 42% in fried liver), rafoxanide (17% in fried muscle, 18% in roast muscle) and triclabendazole (23% in fried liver, 47% in roast muscle). Migration of residues from muscle into expressed cooking juices varied between drugs, constituting 0% to 17% (levamisole) of total residues remaining after cooking. With the exception of nitroxynil, residues of anthelmintic drugs were generally resistant to degradation during roasting and shallow frying. Conventional cooking cannot, therefore, be considered a safeguard against ingestion of residues of anthelmintic veterinary drugs in beef. © 2011 Taylor & Francis.

Impact of Age on the Importance of Systolic and Diastolic Blood Pressures for Stroke Risk:The MOnica, Risk, Genetics, Archiving, and Monograph (MORGAM) Project

This study investigates age-related shifts in the relative importance of systolic (SBP) and diastolic (DBP) blood pressures as predictors of stroke and whether these relations are influenced by other cardiovascular risk factors. Using 34 European cohorts from the MOnica, Risk, Genetics, Archiving, and Monograph (MORGAM) Project with baseline between 1982 and 1997, 68 551 subjects aged 19 to 78 years, without cardiovascular disease and not receiving antihypertensive treatment, were included. During a mean of 13.2 years of follow-up, stroke incidence was 2.8%. Stroke risk was analyzed using hazard ratios per 10-mm Hg/5-mm Hg increase in SBP/DBP by multivariate-adjusted Cox regressions, including SBP and DBP simultaneously. Because of nonlinearity, DBP was analyzed separately for DBP =71 mm Hg and DBP

Design, recruitment, logistics, and data management of the GEHA (Genetics of Healthy Ageing) project

In 2004, the integrated European project GEHA (Genetics of Healthy Ageing) was initiated with the aim of identifying genes involved in healthy ageing and longevity. The first step in the project was the recruitment of more than 2500 pairs of siblings aged 90 years or more together with one younger control person from 15 areas in 11 European countries through a coordinated and standardised effort. A biological sample, preferably a blood sample, was collected from each participant, and basic physical and cognitive measures were obtained together with information about health, life style, and family composition. From 2004 to 2008 a total of 2535 families comprising 5319 nonagenarian siblings were identified and included in the project. In addition, 2548 younger control persons aged 50-75 years were recruited. A total of 2249 complete trios with blood samples from at least two old siblings and the younger control were formed and are available for genetic analyses (e.g. linkage studies and genome-wide association studies). Mortality follow-up improves the possibility of identifying families with the most extreme longevity phenotypes. With a mean follow-up time of 3.7 years the number of families with all participating siblings aged 95 years or more has increased by a factor of 5 to 750 families compared to when interviews were conducted. Thus, the GEHA project represents a unique source in the search for genes related to healthy ageing and longevity.