Anthelmintic resistance--looking to the future: a UK perspective

The full extent of anthelmintic resistance in nematodes of farm animals is not known. Resistance can be detected with a faecal egg count reduction test and two in vitro tests, the egg hatch and larval development tests. The sensitivity of these two in vitro tests can be increased by using discriminating doses rather than calculating LD50 values. Only benzimidazole resistance can be detected with PCR based tests because the molecular mechanisms of resistance to levamisole and the macrocyclic lactones remain unknown. Resistance detection is important because it enables the appropriate management strategies to be put in place. The development of resistance is delayed by keeping sufficient parasites in refugia (not exposed to anthelmintic), but the necessary management details have not yet been validated in the field. It is probably too late to use combination products to delay the development of resistance, except in cattle but quarantining animals to prevent introduction of resistant helminths onto a farm is important. Dilution of resistant worms with susceptible ones is only at the preliminary research stage and the application of non-chemical methods of control to delay resistance is not yet a practical option. Extensive research is required to manage resistance, especially in the control of resistance in Fasciola hepatica.     

Only one medicine: the future of comparative medicine and clinical research

This article reviews the roots of comparative medicine and argues that during the 20th century it failed to realise its full potential. New opportunities arise from the growing availability of precise, minimally invasive, clinically compatible techniques, which enable us to benefit from the availability of spontaneous analogues of human disease in animals. Particularly with multifactorial diseases, these offer a unique blend of authenticity and acceptability. To realise the full benefits to both animals and humans, we need much closer alignment of human and veterinary clinical medicine.     

Anthelmintic resistance in New Zealand: A perspective on recent findings and options for the future

A recent national survey on anthelmintic resistance in cattle and sheep in New Zealand indicated that the magnitude of the problem has increased from very low levels only a few years ago to disturbingly high levels now. There is a particular problem with multiple resistance to all three action families of anthelmintic currently available in Ostertagia (= Teladorsagia) spp in sheep, and to both macrocyclic lactones (ML) and benzimidazoles in Cooperia spp in cattle. The prevalence and extent of resistance indicate that all cattle farmers and most sheep farmers should now be using a combination anthelmintic on most occasions just to achieve effective control of all parasites. Despite this, the presence of resistant parasites has generally not been appreciated by the majority of affected farmers, possibly because most have not formally tested to determine the resistance status of nematodes on their farms.

Anthelmintics will remain the cornerstone of gastrointestinal nematode control in sheep and cattle for the foreseeable future but to ensure their continued effectiveness farmers need to be constantly aware of the need to maintain adequate reservoirs of unselected nematodes, i.e. worms in refugia, to minimise the expansion of the resistant population. High-risk practices in relation to selection of resistance need to be identified and avoided or at least their use limited. These include: treating adult animals where there is no identified need, moving newly- treated animals onto ‘clean’ pasture, and failing to effectively quarantine-drench bought-in animals. None of these are new concepts but many have not been adopted or practised. In particular, sheep farmers should endeavour to avoid treating ewes pre-lambing with long-acting anthelmintics. Farmers needs to negotiate a balance between achieving good parasite control and the sustainability of their control options.     

Plants as de-worming agents of livestock in the Nordic countries: historical perspective, popular beliefs and prospects for the future.

Preparations derived from plants were the original therapeutic interventions used by man to control diseases (including parasites), both within humans and livestock. Development of herbal products depended upon local botanical flora with the result that different remedies tended to develop in different parts of the world. Nevertheless, in some instances, the same or related plants were used over wide geographic regions, which also was the result of communication and/or the importation of plant material of high repute. Thus, the Nordic countries have an ancient, rich and diverse history of plant derived anthelmintic medications for human and animal use. Although some of the more commonly used herbal de-wormers were derived from imported plants, or their products, many are from endemic plants or those that thrive in the Scandinavian environment. With the advent of the modern chemotherapeutic era, and the discovery, development and marketing of a seemingly unlimited variety of highly efficacious, safe synthetic chemicals with very wide spectra of activities, herbal remedies virtually disappeared from the consciousness--at least in the Western world. This attitude is now rapidly changing. There is a widespread resurgence in natural product medication, driven by major threats posed by multi-resistant pest, or disease, organisms and the diminishing public perceptions that synthetic chemicals are the panacea to health and disease control. This review attempts to provide a comprehensive account of the depth of historical Nordic information available on herbal de-wormers, with emphasis on livestock and to provide some insights on potentially rewarding areas of "re-discovery" and scientific evaluation in this field.     

Anthelmintic resistance in New Zealand: a perspective on recent findings and options for the future

A recent national survey on anthelmintic resistance in cattle and sheep in New Zealand indicated that the magnitude of the problem has increased from very low levels only a few years ago to disturbingly high levels now. There is a particular problem with multiple resistance to all three action families of anthelmintic currently available in Ostertagia (= Teladorsagia) spp in sheep, and to both macrocyclic lactones (ML) and benzimidazoles in Cooperia spp in cattle. The prevalence and extent of resistance indicate that all cattle farmers and most sheep farmers should now be using a combination anthelmintic on most occasions just to achieve effective control of all parasites. Despite this, the presence of resistant parasites has generally not been appreciated by the majority of affected farmers, possibly because most have not formally tested to determine the resistance status of nematodes on their farms. Anthelmintics will remain the cornerstone of gastrointestinal nematode control in sheep and cattle for the foreseeable future but to ensure their continued effectiveness farmers need to be constantly aware of the need to maintain adequate reservoirs of unselected nematodes, i.e. worms in refugia, to minimise the expansion of the resistant population. High-risk practices in relation to selection of resistance need to be identified and avoided or at least their use limited. These include: treating adult animals where there is no identified need, moving newly treated animals onto 'clean' pasture, and failing to effectively quarantine-drench bought-in animals. None of these are new concepts but many have not been adopted or practised. In particular, sheep farmers should endeavour to avoid treating ewes pre-lambing with long-acting anthelmintics. Farmers needs to negotiate a balance between achieving good parasite control and the sustainability of their control options.     

鱼类的核苷酸营养：研究现状及应用展望（续完）

上期回顾：上一期本刊编辑首先提出向畜牧生产推荐此文的目的,随后简要介绍了核苷酸在动物和水产动物营养上的总体研究概况,并提出了有必要对其在水产动物营养上所起作用进行总结和评估的重要性,最后比较详细地介绍了核苷酸的生物化学特征、水产动物对核苷酸及相关代谢产物的消化和吸收和核苷酸对水产动物化学诱食的作用。     

Classical swine fever in India: current status and future perspective

Classical swine fever (CSF) is a globally significant disease of swine caused by classical swine fever virus. The virus affects the wild boars and pigs of all age groups, leading to acute, chronic, late-onset or in-apparent course of the disease. The disease causes great economic loss to the piggery industry due to mortality, stunted growth, poor reproductive performance, and by impeding the international trade of pig and pig products. In India, CSF outbreaks are reported from most of the states wherever pig rearing is practiced and more frequently from northeast states. In spite of the highly devastating nature and frequent outbreaks, CSF remained underestimated and neglected for decades in India. The country requires rapid and sensitive diagnostic tests for an early detection of infection to limit the spread of the disease. Also, effective prophylactics are required to help in control and eradication of the disease for the development of the piggery industry. This review looks into the economic impact; epidemiology of CSF highlighting the temporal and spatial occurrence of outbreaks in the last two decades, circulation, and emergence of the virus genotypes in and around the country; and the constraints in the disease control, with the aim to update the knowledge of current status of the disease in India. The article also emphasizes the importance of the disease and the need to develop rapid specific diagnostics and effective measures to eradicate the disease.     

Molecular genetic methods in the veterinary clinical bacteriology laboratory: current usage and future applications

In the last 5 years, numerous molecular methods have been published for the detection and characterization of bacteria in the field of veterinary medicine. PCR has been the most commonly used technology. Although not currently used for clinical veterinary diagnosis, new technologies such as liquid-phase hybridization, real-time PCR, pathogen load determination and DNA/protein microarray have been described and have many possible applications in the clinical bacteriology laboratory because of their sensitivity and efficiency. This review describes the basic principles and application of recently published DNA-based molecular techniques for the purpose of veterinary clinical bacteriological diagnosis. It covers advances in probe hybridization technology, DNA/RNA amplification techniques and other molecular detection methods, including 16S rRNA analysis for bacterial characterization and DNA microarrays for bacterial detection. The review briefly summarizes the application of molecular methods for the diagnosis of specific important bacterial infections of animals, and for other animal pathogens that are slow or difficult to isolate in the clinical bacteriology laboratory. In addition, the molecular detection of antimicrobial resistance genes and of bovine mastitis pathogens is briefly described and current commercially available tests are listed.     

Respiratory alkalosis: a quick reference.

This article serves as a quick reference for respiratory alkalosis. Guidelines for analysis and causes, signs, and a stepwise approach are presented.     

Respiratory therapeutics.

Treatment of small animal respiratory diseases tends to target bronchodilators. Although this is not inappropriate, recent advances in the understanding of respiratory diseases have underscored the importance of inflammatory mediators in the pathophysiology of respiratory diseases. Drug therapy of the respiratory tract in small animals is most successful when it is based on a knowledge of normal physiology and disease pathophysiology of respiratory tract diseases.     

An historical perspective on the applications of remote sensing to public health

This brief paper reviews some basic results of almost 100 scientific papers produced in the 1970–1976 time period by the staff and contractors of the Health Applications Office, Johnson Space Center, Houston, TX. These papers were primarily concerned with the use of sensor data collected from satellites and aircraft for environmental analysis, and ultimately for application to human and animal health.

Comment is made on early problem solving, instrumentation development, politics and criticisms of early research efforts, as well as successes and dismal failures which occurred. Philosophical references are made to the sizeable number of problems which still exist in the health field and which might be amenable to solution by the judicious use of remote sensing.     

Frontier medicine: the future and integrative medicine.

Vigorous and prolonged effort is required to gain true mastery of the healing arts. Conventional and complementary medicine have complementary strengths and weaknesses. Like the yin and yang of traditional Chinese medicine, they naturally flow into one another by a process of induction, creating balance. Integrative medicine is the frontier; it is the future. If we are to progress beyond our current understanding and ability to heal, we must work with theoretic models that allow us and our perception to operate "outside the box." For some, this understanding is intuitive. It is through cooperative and collaborative efforts of intuitively adept and technologically adept minds that we can integrate and advance our understanding; increase our ability to predict, prevent, and diagnose disease; and expand our therapeutic options.