Integrated Parasite Management Research Articles

Genetic aspects of sheep parasitic diseases

There is evidence of genetically determined host resistance mechanisms for most of the sheep parasites evaluated. The mechanisms vary; from no or reduced establishment, early expulsion, to suppression of parasites resulting in reduced size and fecundity. There is a need to integrate breeding for parasite resistance with the genetic improvement of production traits in farm animals, aiming for optimum solutions for potentially conflicting responses. Sustainable parasite control must be based on Integrated Parasite Management utilising an interdisciplinary approach.

Integrated parasite management: Products for adoption by the Australian sheep industry

The increasing cost of production loss caused by gastrointestinal nematodes (GIN) highlights the importance of good control programs. However, the endemic nature of anthelmintic resistance also reminds of the need for nonchemical options. Both chemical and nonchemical control options need to be integrated into regional parasite management programs (IPM) with the emphasis on component options determined by factors such as major GIN species, regional climate, property size and enterprise structure. The Integrated Parasite Management of Sheep project was established to develop and demonstrate regional parasite control programs, that integrated chemical and nonchemical options, for the main sheep-producing regions of Australia. The project included research about the ecology of the main endo and ecto-parasites of sheep and a national survey of parasite control practices by sheep producers. IPM approaches developed for two contrasting regions of Australia are discussed.Barriers for the adoption of IPM programs include perceived complexity associated with a multi-component approach, time requirements and difficulty. Facilitating the industry adoption of IPM programs is discussed with relevance to the use of small group extension and involvement of the commercial sector. Perceptions of complexity of IPM may be managed by facilitating adoption of components in a step-wise process such that learning outcomes accumulate over time. Extension efforts must address the needs of industry sectors other than sheep producers and explore user pay approaches. The success of these approaches will depend on the relation of the extra profit to producers, through adoption of IPM programs, with remuneration sufficient to attract a commercial service.

Anthelmintic resistance in cattle nematodes Part 2: Minimising the risk!

With the apparent increase in anthelmintic resistance there is a need to ensure that producers follow best advice recommendations on treating animals. It is generally accepted that the blanket use of anthelmintics in all classes of stock is unsustainable and there is a need to incorporate sustainable integrated parasite management practices with appropriate and practicable use of efficient treatments. Refugia i.e. the parasite population that is unexposed to anthelmintic treatment and available for ingestion by a susceptible host, is considered an area of importance when considering the timing and formulation of treatment strategies and is discussed more fully within the article.

Knowledge Types Used by Researchers and Wool Producers in Australia under a Workplace Learning Typology: Implications for Innovation in the Australian Sheep Industry

This paper reports on research into the learning aspects of adopting integrated parasite management practices for sheep (IPM-s) applying a workplace learning framework. An analysis of four primary data sources was conducted; a postal survey of Australian wool producers, a Delphi process with IPM-s researchers, focus groups and interviews with wool producers. Researchers had a high expectation of conceptual and high level procedural knowledge for IPM-s, while wool producers had a tendency to rely on low- and high-level procedural knowledge for parasite management. Researchers also showed concern for disposition as it related to parasite management. Practices identified as potentially problematic for extension, included worm egg count testing (according to best practice), supplementary feed (specifically for worm management), selecting estimated breeding value-tested rams, weighing and monitoring body condition scores, and keeping written paddock histories. This research provides significant empirical insights into the knowledge differences between researchers and producers that can affect how research is developed and communicated for the IPM-s project to facilitate behaviour change. The identification of some IPM practices as problematic for producers will also allow targeted extension for these practices.

Towards sustainable parasite control practices in livestock production with emphasis in Latin America

Endo and ectoparasites of domestic ruminants directly or indirectly contribute to reduce sustainability affecting food security in subsistence or small scale farming systems, food safety (food borne diseases and pesticide residues), environment (pesticides, pollution and ecotoxicity) and farmer's equity (limited or uneven access to relevant technical information/training). This is especially true for some regions of Latin America where there still are huge areas of natural grazing land for cattle, sheep and goats. Sustainable parasite control is not an absolute concept given the different regions and productive systems of the world and therefore, could have different levels of adoption and impact on farmers. This article develops a conceptual framework to better understand where each region or country is situated in terms of attaining a reasonable increase in animal production while preserving sustainability. Within this context the capacity to prioritize the target parasite species for control according to local epidemiology and production systems, the early diagnosis and monitoring of parasite resistance as well as the availability of well trained field professionals acquire a major role, creating an enabling environment for present and future decision support system approaches. Until new and different means of controlling parasites become available; the challenge is to utilize Good Animal Husbandry Practices and Integrated Parasite Management (IPM) principles in a pragmatic way allowing the rational use of pesticides.

Integrated parasite management for sheep reduces the effects of gastrointestinal nematodes on the Northern Tablelands of New South Wales

An experiment was conducted over 2 years on six commercial farms to quantify the costs of gastrointestinal nematode parasitism on grazing Merino ewes on the Northern Tablelands of New South Wales. To determine the effect of worm management practices, three farms implemented integrated parasite management (IPM) strategies and three farms continued to implement regionally typical industry practice (TYP). On each farm, 120 ewes born in 2006 and 120 mature age ewes were selected at shearing in 2007. Of these, 60 in each flock were serially treated with anthelmintics (CAP treatment) to suppress worm populations and the other 60 ewes were managed according to their respective farm management strategies (NOCAP treatment). Among NOCAP ewes, worm egg counts were significantly reduced over both years by IPM compared with TYP despite IPM farms requiring fewer anthelmintic treatments (3.5 vs 4.5 per year). In Year 1, mortality of sheep because of worms (CAP vs NOCAP) was significant on TYP farms (10.5%, P < 0.01) but was not apparent on IPM farms. Throughout the study, NOCAP ewes had significantly lower growth rates (–2.8 ± 0.1 kg/year, P < 0.01), produced less greasy wool (–170 ± 20 g, P < 0.01) and had reduced fibre diameter (–0.28 ± 0.05 μm, P < 0.01) when compared with CAP ewes. These effects were apparent for both TYP and IPM management. The results confirm the significant production loss caused by worms in a northern, summer rainfall region and show that IPM reduces the effect of worms and frequency of anthelmintic treatment compared with typical methods currently used by the industry.

Sustainable use of anthelmintics in an Integrated Parasite Management Program for sheep nematodes

Anthelmintic resistance is a major problem affecting sheep nematode control; however, chemical treatments will always be a likely routine part of any parasite control program. The present paper, with the aim of minimising the selection pressure for worsening anthelmintic resistance, outlines important practical and strategic aspects of planning the anthelmintic component of an integrated approach to sheep worm management.

The Five Point Check © for targeted selective treatment of internal parasites in small ruminants

Although the principle of targeted selective treatment (TST) has become accepted as a valuable tool in reducing the speed of onset of anthelmintic resistance (AR) and a key part of sustainable and holistic integrated parasite management ( sh IPM), the only practical and proven on-farm method developed to date has been the FAMACHA © system of clinical anaemia evaluation. This is by its nature limited to use in the few haematophagous parasites that cause anaemia, especially Haemonchus contortus. The principle of TST can be extended for use against other important internal parasites, provided that the system developed is practical, economical and reasonably able to identify animals at risk of being overwhelmed by current internal or external parasite challenge. Candidates for an extended TST system have included nasal discharge (for nasal bots), paling of ocular mucous membranes for anaemia (for haematophagous worms), submandibular oedema or bottle jaw (for haematophagous worms and conical fluke), body condition score (for worms causing loss of condition) and faecal fouling or dag score (for worms causing diarrhoea). The potential uses and limitations of each of these quick, crush-side checks are listed and discussed and data supporting their implementation is summarised. A practical, farmer-friendly guide has been developed to enable users to: (i) evaluate small ruminants rapidly for signs of parasitism, (ii) make effective assessments, (iii) identify the likely parasites, (iv) select anthelmintic groups that could be used, (v) use practical systems for temporarily identifying treated animals and (vi) know the limitations of the system. This system has been named the Five Point Check © (5·√ ©) for international, multilingual use and constitutes a further, practical extension of TST. This can make a useful contribution to sh IPM.

EFECTO DE PAULLINIA CLAVIGERA “SACHA YOCO” (SAPINDACEAE) SOBRE LA ECLOSIÓN DE HUEVOS DE FASCIOLA HEPATICA

La utilización de extractos vegetales representa una alternativa para el manejo integrado de parásitos enSalud Pública, debido a su bajo costo y al menor impacto sobre el ambiente al conservar la biodiversidad. El presente trabajo tuvo como objetivo determinar el efecto de los extractos de la planta amazónica Paullinia clavigera Simpson “Sacha yoco” (Sapindaceae) sobre la eclosión de huevos de Fasciola hepatica L. (Trematoda: Fasciolidae). Los huevos fueron obtenidos de bovinos procedentes del camal de Yerbateros, Lima, Perú. Se realizó el tamizaje fitoquímico y se prepararon los extractos hexánico, clorofórmico e hidroalcohólico a partir de la corteza y hoja de P. clavigera. Se realizaron bioensayos para determinar el efecto de Sacha yoco sobre la eclosión de los huevos, los cuales fueron incubados en los extractos a 22° ± 2º C durante 21 días y finalmente expuestos a la luz por 12 h. No existieron diferencias significativas entre el número de huevos de F. hepatica expuestos en cada una de las concentraciones en los bioensayos. Solo existió efecto en la eclosión de los huevos de F. hepatica por el extracto hexánico de corteza de P. clavigera a las dos concentraciones más altas. La toxicidad observada en el extracto hexánico de corteza de P. clavigera pudiera deberse a la presencia de triterpenos, flavonoides y quinonas.

Targeted selective treatment for worm management—How do we sell rational programs to farmers?

Seriously escalating global anthelmintic resistance in gastrointestinal nematodes of small ruminants has spawned a variety of alternatives to anthelmintics for worm management, based on the need for sustainable Integrated Parasite Management (sIPM). Pivotal to the sIPM approach is the concept of refugia, the proportion of a given parasite population that escapes exposure to control measures. By balancing drug applications with the maintenance of refugia, the accumulation of anthelmintic resistance alleles in worm populations can be considerably delayed, while still providing good levels of control. The over-dispersed nature of parasitic infections provides an opportunity to achieve this balance, by targeting treatments to the members of a flock or herd that are least tolerant to nematode infection. However, implementation of this strategy has only recently become feasible, with the development of the FAMACHA © system for clinical evaluation of anaemia due to haemonchosis. Subsequently, the use of milk yields has proven an effective indicator in dairy goats infected predominantly with nematodes other than Haemonchus contortus. In addition, short-term weight changes and perhaps also body condition scoring may provide indices of parasitism, permitting the rapid identification of animals likely to benefit from treatment. However, sIPM and refugia-based approaches are more complex than whole-flock treatments in conventional programs, and adoption by farmers is most likely where the theoretical basis is understood. As close communication with informed advisors is generally limited, there is a danger that sIPM will remain a theoretical concept without alternative modes of communication. The development of computer-based decision support programs, which use epidemiological, seasonal and clinical information to provide recommendations for specific situations, should be accorded high priority in the future development of worm management systems.

Regulation of the resistance to nematode parasites of single- and twin-bearing Merino ewes through nutrition and genetic selection

Periparturient Merino ewes obtained from lines of sheep that had been selected either for increased resistance to Haemonchus contortus (R) or at random (C) were supplemented, while grazing at pasture, with either nil or 250 g/day cottonseed meal (CSM) for the 6 weeks prior to or the 6 weeks after the start of parturition. Ewes from both supplement groups had lower (mean 66% reduction) faecal egg counts (FECs) during the postpartum period and this coincided with a period of maternal body weight loss. Factors which increased the rate of maternal body weight loss, such as pregnancy and lactation status, also increased FEC. Evidence is presented that the magnitude of the periparturient rise (PPR) in FEC in grazing ewes will be greatest during periods of maternal weight loss and at these times supplementation to increase metabolisable protein (MP) supply will be most effective in increasing resistance to nematode parasites. The resistance of R ewes to nematode parasites was greater than that of C ewes throughout the experiment and was sufficiently low such that anthelmintic treatment in a commercial environment may not have been required. Irrespective of actual FEC, ewes from all treatment combinations exhibited a PPR in FEC. Reduced FEC of R ewes resulted in reduced apparent pasture larval contamination after 18 weeks of continuous grazing but supplementation was ineffective in this regard. It is suggested that integrated parasite management (IPM) programs for periparturient ewes should make use of both protein supplementation and genetic selection to increase worm resistance and reduce dependency on anthelmintics for worm control.

Managing parasiticide resistance

Resistance to antiparasitic drugs is all too common in parasites of veterinary interest. The fact that resistance has arisen in so many different species of parasite and hosts against so many different drugs and in so many geographic areas suggests that the resistances may have common features. Such features may be useful in generating ideas for resistance management. Although describing the nature and presence of resistance remains an important objective, there is now a pressing need to develop improved methods of detection of resistance and to devise schemes for integrated parasite management (IPM). Multidisciplinary teams of researchers and extension workers are exploring new ways to deal with the problem of resistance.

Irradiated vaccines for helminth control in livestock

For nearly 40 years, irradiated larval vaccines have been available for the control of parasitic bronchitis in cattle and sheep caused by Dictyocaulus spp. Despite research on a number of other host/parasite systems, no other vaccines have been commercially successful. Vaccination could provide a useful addition to other control methods in an integrated parasite management system where the criteria for vaccine success may not be complete control and sterile immunity, but a sufficient reduction in worm burden to decrease overall reinfection levels at the flock/herd level and, hence, prevent clinical disease and subclinical effects including production loss. Indeed, vaccination against Dictyocaulus spp. relies on continued natural infection to maintain levels of immunity. However, the difficulties of producing live larval vaccines are often cited as a reason why this line of research should not be pursued. This paper discusses some of the difficulties in vaccine production and offers some solutions and recommendations for those wishing to develop and register irradiated larval vaccines for other helminth diseases.

Fish parasites as indicators of freshwater ecosystem stability and change

Host–parasite relationships can be conceptualised either narrowly, where the parasite is metabolically dependent on the host, or more broadly, as suggested by an ecological–evolutionary and complex systems perspective. In this view Host–parasite relationships are part of a larger set of ecological and co-evolutionary interdependencies and a complex adaptive system. These interdependencies affect not just the hosts, vectors, parasites, the immediate agents, but also those indirectly or consequentially affected by the relationship. Host–parasite relationships also can be viewed as systems embedded within larger systems represented by ecological communities and ecosystems. So defined, it can be argued that Host–parasite relationships may often benefit their hosts and contribute significantly to the structuring of ecological communities. The broader, complex adaptive system view also contributes to understanding the phenomenon of disease emergence, the ecological and evolutionary mechanisms involved, and the role of parasitology in research and management of ecosystems in light of the apparently growing problem of emerging infectious diseases in wildlife and humans. An expanded set of principles for integrated parasite management is suggested by this perspective.