Use Of Parasiticides Research Articles

Workshop write up: responsible use of parasiticides

Parasiticides are the first line of treatment and prevention of ectoparasitic infections and are among the most prescribed medications in small animal practice. Many ectoparasiticide products are available, with an excellent record of safety and efficacy, significantly improving the quality of life of companion pets. In recent years, there have been concerns about the environmental impact of (and development of resistance to) these drugs. The future of ectoparasite control hinges on the responsible use of ectoparasiticides. In this workshop session, Hany Elsheikha explored ways to improve knowledge, awareness, attitudes and behaviours regarding the judicious usage of parasiticides.

Responsible use of parasiticides in pets

Parasiticides are an integral part of parasite treatment and prevention in pets. Despite their importance as life-saving medications and a major contributor to better health and quality of life, widespread and inappropriate use of parasiticides could have important consequences. Concerns over parasite control practices involving ‘blanket-treatment’ have caused key organisations to call for more responsible use of parasiticides to minimise the risk of environmental contamination and limit the development of antiparasitic drug resistance. Veterinary professionals are encouraged to follow a more targeted and individualised risk-based approach to parasite control. However, successful adoption and effective implementation of this new approach requires the veterinary profession to overcome many barriers and contextual differences in the way effective parasite control is perceived by the various stakeholders. Recently, evidence-based diagnosis (treatment based on confirmed diagnosis) together with antiparasitic drug stewardship (avoiding unnecessary antiparasitic use in pets which do not benefit from treatment) have been suggested to reconcile the trade-offs between avoiding parasiticide overuse and achieving effective parasite control. Although these new approaches cannot yet fully address the challenges of attaining optimal parasite control, they have the potential to improve the outcomes of parasite treatment and preserve the efficacy of parasiticides, the most essential component of any parasite control regimen.

Dewormers, Dung Beetles, and Decision Making: Understanding Rangeland Livestock Producers’ Parasiticide Use

Using parasiticides, or chemical dewormers, on rangeland livestock is a decision that impacts not only livestock health but also broader ecosystem functions. Although we know that livestock producers in the United States are increasingly using parasiticides, we know little about what sociopsychological factors are driving their decision making processes. Following the theory of planned behavior (TPB), this study investigates producers’ intention to stop or reduce their use of parasiticides using logistic regression techniques. Survey data were collected from a random sample of 2 416 farming operations in South Dakota grazing livestock. While controlling for socioeconomic and demographic factors, we find that among the three TPB constructs of attitudes, subjective norms, and perceived behavioral control, negative attitudes about the effects of chemical dewormers are the only factor with a relationship to producers’ reduction in parasiticide use. We also find that those with a college degree were significantly more likely to reduce or stop using parasiticides. The adapted model of TPB appears to provide a suitable framework for examining parasiticide use among South Dakota producers and our findings also suggest that future interventions aimed at promoting rangeland sustainability should include an understanding of producers’ attitudes in relation to desired behaviors.

Macrocyclic lactone residues in cattle dung result in a sharp decline in the population of dung beetles in the rangelands of northern China

Dung beetles perform important ecosystem functions including livestock dung removal, nutrient recycling and parasite control. However, more research is being done on the effects of veterinary drug residues on dung beetles due to the widespread usage of macrocyclic lactone (ML). While a number of research on this topic have been published in Europe, Africa and America, few have been in Asia. In the past decade, standard veterinary antibiotics administration in livestock grazing systems in the rangelands of northern China has included ML. In the present study, the abundance, species richness, diversity, and evenness of dung beetles in the rangelands of northern China in 2020 were examined and compared to the reference data from 2010, when parasiticide had never been used, to better understand the changes in dung beetle communities after the long-term use of parasiticides. The abundance and diversity of dung beetle populations in the current three rangelands in northern China were first investigated using a baited-trap experiment. The findings revealed a 67.3 % decrease in dung beetle abundance and a shift in the dominant species from Aphodiidae to Staphylinidae. Cattle dung on the three studied rangelands included high ML residues ranging from 22.7 ppb to 130.1 ppb. According to the results of the correlation analysis, the beetle abundance and ML residues in cattle dung were negatively correlated. In the meantime, the findings of a field examination of undecomposed cattle dung on 34 rangelands in northern China revealed that the coverage rate of dried cattle dung pats ranged from 2 % to 6 % on 24 rangelands and reached above 10 % on four rangelands. According to the current findings, the decrease in cattle dung beetles would slow down the decomposition of cattle dung pats and decrease the available grazing area. Therefore, the dung beetle community in the rangelands of northern China would be negatively impacted by the frequent administration of ML to cattle. This would result in significant changes to the biogeochemical cycle of rangeland and had a negative impact on the development of local husbandry. During rangeland management, more attention should be given to the dynamic changes of coprovorous insects and the application of veterinary antibiotics.

UK parasite risk factors and control challenges

Endemic and emerging parasites pose a risk to companion animals and their owners. Emerging parasites can also impose a significant public health burden. The discovery of new parasites, the insurgence of endemic ones, and the emergence of new information has made managing parasitic diseases a topical subject for veterinarians, who are now starting to see more patients with these diseases. Better understanding of the extent and burden of parasites on animals and humans is essential for control interventions. This article discusses the known risk factors of UK parasites in the current literature, use of parasiticides in small animal medicine, known challenges to effective parasite control, risks of parasiticides and current guidelines surrounding their use.

Oestrid myiasis at a cross-road

The oestrids are a genuinely unique group of Diptera that represent many species whose larvae parasitize mammals, feeding on live tissues of a wide range of hosts, from mice to elephants, causing obligatory myiases. Those have had greatest impact on the activities of humans and their use of animals (e.g., as food, recreation, in the conduct of wars). To a large extent their impact has been controlled through the use of therapeutic application of synthetic chemical treatments. While in some limited cases eradication has been achieved, it is unlikely to become the norm as these parasites seem well adapted to survive at low population densities and small smoldering foci are likely to present a challenge in the future. Should organic production eschew the use of parasiticides, other than for rescue of seriously ill animals, the foci of infection by these parasites will remain. In this article, we explore current scientific information on this group of parasites that may have become an anachronism in modern livestock parasitology, identify gaps in our knowledge as well as the suggestions for the management of these parasites in the era of genomics and proteomics.

Importation of cats and risk of parasite spread: a Caribbean perspective and case study from St Kitts

BackgroundIn more recent years, international travel with cats has increased. The distribution of cat parasites can change with this movement. Already, subtropical and tropical parasites have been reported by veterinarians in areas where they are not naturally present. Understanding the prevalence of tropical and subtropical parasites in Caribbean islands and the risk of importation to temperate areas could enable improved prevention recommendations and border control import requirements.MethodsWe present a study focused on cat owning students enrolled in a Doctor of Veterinary Medicine (DVM) programme on St Kitts. Owners were interviewed about their cats and their use of parasiticides. Cats were examined for Trichuris felis and Platynosomum fastosum using sugar flotation, Lynxacarus radovskyi using an adhesive tape test, and Dirofilaria immitis using commercial antigen and antibody tests.ResultsData on 115 cats owned by 87 DVM students were collected and 90 cats, all expected to travel to the USA, were examined. Most of the cats were adults and born in St Kitts. Prevalence was reported as 6.8% (95% confidence interval (CI): 2.2–15.1%) for T. felis, 16.2% (95% CI: 8.7–26.6%) for P. fastosum and 6.8% (95% CI: 2.5–14.3%) for L. radovskyi. All D. immitis tests were negative. DVM students reported a high level of deworming (83.3% of the cats), but the number of cats treated per recommendations were low (56.1% for endoparasites and 70.8% for ectoparasites). Also, there was a lack of clarity regarding the purpose of the treatments used and treatments did not appear to be targeted for the parasites present.ConclusionOur results indicate a low prevalence of the parasites of interest in the DVM student cat population compared to other prevalence studies from the Caribbean. However, a degree of non-compliance with parasiticide uses and the high number of cats traveling to the USA indicate a medium risk of importation of tropical and subtropical cat parasites to temperate areas. We recommend stronger health inspections and health screening requirements at the borders including the development of specific parasiticide protocols for cat importation.

Isospora bocamontensis (Protozoa: Apicomplexa) in captive yellow cardinal Gubernatrix cristata (Passeriformes: Emberezidae)

The yellow cardinal (Gubernatrix cristata) is a passerine found in southern Brazil, especially along the border with Uruguay and Argentina. It is an endangered species and its population is decreasing. Among the parasites that affect passerines, the genus Isospora is the most easily found in both captive and free-living birds. This parasite commonly causes injury to the intestinal tissue and could occasionally affect other organs. In this work we examined the occurrence of coccidiosis in captive yellow cardinals and its association with factors such as sex, use of parasiticides, type of enclosure, contact with feces, type of food and cleaning frequency. We collected fecal samples of 45 yellow cardinals, healthy and kept in captivity, in late afternoon at the end of the reproductive period. The examination showed parasitic infection by Isospora bocamontensis in 44.5% of the birds. This infection is not influenced by the sex of birds, but is significantly affected by the type of enclosure, contact with the feces, use of parasiticides, type of food and cleaning frequency. The results indicate that to keep yellow cardinals captive, these factors must be observed.

Medicines for sea lice.

Sea louse (Family Caligidae: genera Caligus and Lepeophtheirus) infection of farmed salmonids represents a significant threat to animal welfare and undermines profitability. Lice may also act as vectors for the transmission of viral and bacterial pathogens. Pest-control programmes parallel those deployed in terrestrial livestock farming and include the use of parasiticides. The authorisation process for fish medicines varies widely between salmon farming countries and undue regulatory constraint may place farmers in one country at a competitive disadvantage. In many jurisdictions, fish are a 'minor' species and mounting demands for environmental assessment increase registration costs. A successful integrated louse-management strategy requires free access to a range of effective, chemically unrelated active ingredients deployed according to current best practice. Over-reliance on a limited number of products will lead, inevitably, to resistance, which is difficult to counter.

Historical perspective of cyathostomes: prevalence, treatment and control programs

Small strongyles are highly prevalent in horses and can be found worldwide. Even though over 50 species of these parasites have been described, about 10 species comprise the bulk of the total number present in horses. Efforts to control small strongyles and other equine internal parasites have been undertaken for many years. Some of the early medications and control measures provided questionable activity against endoparasites; whether effective or not, they could be detrimental to the horse. Beginning in the early 1900s, scientific effort was used to evaluate activity of antiparasitic compounds. Only a relatively low number of classes of compounds has been used for parasite control. Progressively, in time, newer drugs have become broad-spectrum, safer, and available in lower dose rates than previously. With extensive use of parasiticides, small strongyles have been found to be resistant to all commercially-available classes of compounds except the macrocyclic lactones. Innovative parasite-control programs, relying less on drugs, need to be developed.

Review: Approaches to New Parasiticides

Intensive use of parasiticides has sometimes led to severe resistance in arthropods and helminths of veterinary importance. In the context of the growing awareness of parasitic diseases, this has created a public demand for effective and safe control agents. During the last two decades considerable knowledge in parasite neurophysiology and endocrinology has accumulated which allows the development of new screening procedures and target-site-directed approaches for the discovery of new drugs. The suitability of this strategic approach is discussed on the basis of recent discoveries of new chemical and natural compounds. In particular, target sites such as GABA A receptors, muscarinic and nicotinic acetylcholine receptors, cuticle synthesis and degradation, ecdysteroid receptors, the calcium release channel and semiochemicals have been selected in order to demonstrate the current approaches to identify new chemical entities, biologically active against nematodes and arthropods.