Equine Parasites Research Articles

Anthelmintic resistance in equine parasites – detection, potential clinical relevance and implications for control

During the past two decades anthelmintic resistance in equine parasites has been found in the group of small strongyle species (cyathostomins) and in the ascarid species Parascaris equorum. The ubiquitous nature and possible severe consequences of disease with these nematodes make them the prime targets of current worm control programmes. Traditional control strategies mainly rely on the strategic application of anthelmintics, currently represented by three major drug classes: benzimidazoles (BZ), the tetrahydropyrimidine pyrantel (PYR) and macrocyclic lactones (ML). Following decades of routine and frequent anthelmintic applications, many cyathostomin populations on horse farms in industrialised countries must be considered as resistant to BZ anthelmintics. However, to date no published cases of cyathostomin disease specifically associated with anthelmintic resistance were reported. Possibly this is due to the generally subclinical and unspecific symptoms associated with cyathostomin infections. Nevertheless, exclusive reliance on the ML drug class may increase the threat of clinical disease due to drug-resistant cyathostomins.More recently, P. equorum has been reported as having developed resistance against ivermectin and moxidectin, two representatives of the ML-class. These anthelmintics are currently the most frequently used drug class in horses. This nematode species is mainly found in foals and in younger horses due to the development of immunity following exposure to infection. Infection with P. equorum can result in clinically drastic consequences such as obstruction and/or penetration of the small intestine, the latter usually leading to death.In conclusion, on horse farms the efficacy of anthelmintic treatments should be examined routinely for each drug class. Several factors can influence the rate at which anthelmintic resistance develops; high frequency of treatment being one of the most important. Modern control strategies should therefore attempt to significantly reduce anthelmintic treatments. Several pasture and farm management practices found to be negatively associated with nematode and anthelmintic resistance prevalence will be discussed in the review presented here.

Resistance to avermectin/milbemycin anthelmintics in equine cyathostomins – Current situation

Avermectins and milbemycins (AM) are potent compounds against all major nematode parasites, but their continuous usage has led to the development of widespread resistance in many of the important species of ruminant and equine parasites. The exception to this has been the cyathostomins, where AM resistance was recently first reported only after decades of drug exposure. Data from a Brazilian study suggests that AM resistance has developed in cyathostomins and reports of shortened egg reappearance periods after ivermectin treatment have been published recently from USA and Germany. Thus, AM resistance in cyathostomins is an emerging worldwide concern, but there is only limited amount data on the extent of this problem. To limit the development and spread of AM-resistant cyathostomins the equine industry must implement new strategies for worm control, and the veterinary parasitology community must develop and validate improved protocols for detecting anthelmintic resistance in the field.

Sustainable equine parasite control: Perspectives and research needs

Clinically important equine parasites are ubiquitous in managed horse populations. The traditional approach to parasite control is frequent administration of anthelmintics to all horses on a farm. However, increasing levels of anthelmintic resistance is forcing horse owners and veterinarians to shift this control paradigm. Treatment regimens involving routine deworming of all horses throughout the year are now being replaced by more sustainable approaches, which take in to account the importance of maintaining adequate parasite refugia. The selective therapy principle has been recommended for more than 15 years, but there is limited experience with this approach. The relative magnitude of the faecal egg count for an individual horse is a consistent trait, and this provides a reliable basis for selective therapy. But no studies have evaluated the consequences of selective therapy in the long-term, and such studies are strongly needed to validate this approach. Importantly, it remains unclear how selective therapy may affect the prevalence and intensity of other parasites of significant pathogenic potential (e.g. Strongylus vulgaris), which have become uncommon due to years of intensive chemotherapy. Consequently, a selective approach requires vigilant surveillance of the parasite fauna and intensity. This places a demands for reliable diagnostic tools. Also noteworthy is the fact that the majority of equine nematode parasites are more pathogenic during their larval stages, when they cannot be detected by traditional egg counting techniques. Consequently, parasite-specific diagnostic tools capable of assessing prepatent parasite burdens, and able to differentiate between strongyle species of different pathogenic potentials, would be of great value to the equine clinician. Tools for detecting infections with the tapeworm Anoplocephala perfoliata are laborious, difficult to interpret, and at present there is no established method to evaluate treatment efficacy. Thus, better diagnostic tools are needed for tapeworms as well. Biological control, especially the predacious fungi have demonstrated good potential as an adjunct for strongyle control and such a product could easily have a market in equine establishments. In summary, there is general agreement that the traditional treat-all at frequent interval approach should be abandoned, and that optimal parasite control can be maintained with far fewer anthelmintic treatments. But better diagnostic techniques and more evidence documenting the long-term consequences of selective therapy programs are needed to develop and validate systems for sustainable equine parasite control.

Practical aspects of equine parasite control: A review based upon a workshop discussion consensus

Development of resistance of several important equine parasites to most of the available anthelmintic drug classes has led to a reconsideration of parasite control strategies in many equine establishments. Routine prophylactic treatments based on simple calendar-based schemes are no longer reliable and veterinary equine clinicians are increasingly seeking advice and guidance on more sustainable approaches to equine parasite control. Most techniques for the detection of equine helminth parasites are based on faecal analysis and very few tests have been developed as diagnostic tests for resistance. Recently, some molecular and in vitro based diagnostic assays have been developed and have shown promise, but none of these are currently available for veterinary practice. Presently, the only reliable method for the detection of anthelmintic resistance is a simple faecal egg count reduction test, and clinicians are urged to perform such tests on a regular basis. The key to managing anthelmintic resistance is maintaining parasite refugia and this concept is discussed in relation to treatment strategies, drug rotations and pasture management. It is concluded that treatment strategies need to change and more reliance should now be placed on surveillance of parasite burdens and regular drug efficacy tests are also recommended to ensure continuing drug efficacy. The present review is based upon discussions held at an equine parasite workshop arranged by the French Equine Veterinary Association (Association Vétérinaire Equine Française, AVEF) in Reims, France, in October 2008.

An evidence‐based approach to equine parasite control: It ain't the 60s anymore

SummaryMost veterinarians continue to recommend anthelmintic treatment programmes for horses that derive from knowledge and concepts more than 40 years old. However, much has changed since these recommendations were first introduced and current approaches routinely fail to provide optimal or even adequate levels of parasite control. There are many reasons for this. Recent studies demonstrate that anthelmintic resistance in equine parasites is highly prevalent and multiple‐drug resistance is common in some countries, but few veterinarians take this into account when making treatment decisions or when recommending rotation of anthelmintics. Furthermore, the current approach of treating all horses at frequent intervals was designed specifically to control the highly pathogenic large strongyle, Strongylus vulgaris. But this parasite is now quite uncommon in managed horses in most of the world. Presently, the cyathostomins (small strongyles) are the principal parasitic pathogens of mature horses. The biology and pathogenesis of cyathostomins and S. vulgaris are very different and therefore require an entirely different approach. Furthermore, it is known that parasites are highly over‐dispersed in hosts, such that a small percentage of hosts harbour most of the parasites. The common practices of recommending the same treatment programme for all horses despite great differences in parasite burdens, recommending prophylactic treatment of all horses without indication of parasitic disease or knowing what species of parasites are infecting the horses, recommending use of drugs without knowledge of their efficacy and failing to perform diagnostic (faecal egg count) surveillance for estimating parasite burdens and determining treatment efficacy, are all incompatible with current standards of veterinary practice. Consequently, it is necessary that attitudes and approaches to parasite control in horses undergo a complete overhaul. This is best achieved by following an evidence‐based approach that takes into account all of these issues and is based on science, not tradition.

In vitro predatory activity of nematophagous fungi and after passing through gastrointestinal tract of equine on infective larvae of Strongyloides westeri

Three isolates of predator fungi Duddingtonia flagrans (AC001), Monacrosporium thaumasium (NF34), and Arthrobotrys robusta (I-31) were assessed in in vitro test regarding the capacity of prey infective larvae (L(3)) Strongyloides westeri. Compared to control, without fungus, there was a significant decrease (P < 0.01) of 80.4%, 67.9%, and 72.8% in means of infective larvae S. westeri recovered from treatments with isolates AC001, NF34, and I-31, respectively. All tested isolates were efficient in the capture of S. westeri (P > 0.01) in vitro test. Linear regression coefficients of treated and control groups were -0.21 for control, -0.32 for D. flagrans, -0.34 for M. thaumasium, and -0.22 for A. robusta. In the following, isolates AC001 and NF34 were assessed in vivo regarding the capacity of supporting the passage through equine gastrointestinal tract without loss of ability of preying infective larvae S. westeri. Fungal isolates survived the passage and were efficient in preying L(3) since the first 12 h of collection (P < 0.01) in relation to the control group (without fungus). Compared to control, there was a significant decrease (P < 0.01) of 76.4% and 76.7% (12 h), 86.4% and 85.9% (24 h), 88.3% and 87.7% (48 h), and 89.9% and 87.2% (72 h) in means of infective larvae S. westeri recovered from treatments with isolates AC001 and NF34, respectively. Linear regression coefficients of L(3) of recovered S. westeri regarding the collections due to time were 1.93 for control, -3.52 for AC001, and -2.64 for NF34. Fungi D. flagrans and M. thaumasium (NF34) have demonstrated to be promising for use in the biological control of equine parasite S. westeri.

Evaluation of the in vitro growth-inhibitory effect of epoxomicin on Babesia parasites

Epoxomicin potently and irreversibly inhibits the catalytic activity of proteasomal subunits. Treatment of proliferating cells with epoxomicin results in cell death through accumulation of ubiquinated proteins. Thus, epoxomicin has been proposed as a potential anti-cancer drug. In the present study, the inhibitory effects of epoxomicin on the in vitro growth of bovine and equine Babesia parasites were evaluated. The inhibitory effect of epoxomicin on the in vivo growth of Babesia microti was also assessed. The in vitro growth of five Babesia species that were tested was significantly inhibited ( P < 0.05) by nanomolar concentrations of epoxomicin (IC 50 values = 21.4 ± 0.2, 4 ± 0.1, 39.5 ± 0.1, 9.7 ± 0.3, and 21.1 ± 0.1 nM for Babesia bovis, Babesia bigemina, Babesia ovata, Babesia caballi, and Babesia equi, respectively). Epoxomicin IC 50 values for Babesia parasites were low when compared with diminazene aceturate and tetracycline hydrochloride. Combinations of epoxomicin with diminazene aceturate synergistically potentiated its inhibitory effects in vitro on B. bovis, B. bigemina, and B. caballi. In B. microti-infected mice, epoxomicin caused significant ( P < 0.05) inhibition of the growth of B. microti at the non-toxic doses of 0.05 and 0.5 mg/kg BW relative to control groups. Therefore, epoxomicin might be used for treatment of babesiosis.

Drug Resistance in Equine Parasites: An Emerging Global Problem

Effective parasite control is essential for the maintenance of optimal health and performance in the horse. The worldwide escalation of parasite resistance is a major cause of concern for the horse industry. Parasite resistance to every main class of equine anthelmintic has been documented. Furthermore, dual and cross resistance also have been widely reported, despite different climatic and management practices seen throughout the world. Studies documenting parasite resistance to major classes of equine anthelmintics are discussed. Disagreement among researchers exists regarding how to effectively control equine internal parasites. Current theories of factors leading to resistance and control programs are discussed. It is clear that parasite resistance and control in the horse is an area requiring continued intensive study.

Cloning and molecular characterization of tick kynurenine aminotransferase (HlKAT) from Haemaphysalis longicornis (Acari: Ixodidae)

A complementary DNA coding a novel kynurenine aminotransferase (KAT) molecule from Haemaphysalis longicornis tick embryo was cloned and characterized. The transcription of the HlKAT occurs at all stages during tick development as well as in the midgut, salivary glands, ovary, and synganglion of adult ticks, and protein expression levels increased during the blood-feeding course. The HlKAT gene without signal peptide was successfully expressed as a glutathione S-transferase fusion protein in soluble form, which is capable of catalyzing the transamination of kynurenine and 3-hydroxykynurenine to kynurenic acid and xanthurenic acid, respectively. The purified recombinant HlKAT showed dose-dependent inhibition effect on the growth of equine babesial parasite, Babesia caballi, in in vitro culture. All results suggested that a specific HlKAT is present in tick and HlKAT may play an important physiological role in H. longicornis. This is the first report of a member enzyme of tryptophan pathway in Chelicerata.

Equine parasites: diagnosis and control - a current perspective

Equine parasites: diagnosis and control - a current perspective

Restrictions of anthelmintic usage: perspectives and potential consequences

Given the increasing levels of anthelmintic resistance in equine parasites, parasitologists now recommend traditional treatment approaches to be abandoned and replaced by more sustainable strategies. It is of crucial importance to facilitate veterinary involvement to ensure that treatment decisions are based on parasitic knowledge. Despite recommendations given for the past two decades, strategies based on the selective therapy principle have not yet been implemented on a larger scale in equine establishments. In contrast, treatment regimens appear to be derived from recommendations originally given in 1966. The province of Quebec in Canada, and an increasing number of European countries, have implemented prescription-only restrictions on anthelmintic drugs. Denmark introduced this legislation ten years ago, and some evidence has been generated describing potential consequences. It is without dispute that Danish veterinarians are now deeply involved with parasite management in equine establishments. However, little is known about the impact on levels of anthelmintic resistance and the risk of parasitic disease under these circumstances. In addition, the legislation makes huge demands on diagnosis and parasite surveillance. No data have been published evaluating fecal egg count techniques and larval culture methods as clinical diagnostic tools, and very little is known about potential correlations with actual worm burdens. This article provides a general review of anthelmintic strategies currently used in equine establishments and outlines the recommendations now given for parasite control. Preliminary experience with prescription-only restrictions in Denmark is presented and current research needs to further evaluate this approach are discussed.

Classes and crossreactivity of proteinases in the excretory–secretory products of Caenorhabditis elegans

Proteinases released during the in vitro maintenance of asynchronous cultures of the free-living nematode Caenorhabditis elegans were characterized on the basis of subunit composition, fluorogenic substrate specificity, inhibitor sensitivity and pH optima. Cysteine proteinases are present in the excretory-secretory products (ESP) as indicated by the hydrolysis of cathepsin fluorogenic substrates and confirmed by immunoblotting. Serine proteinases were predominant as indicated by substrate gel analysis and inhibitor studies. The presence of metallo-proteinases was also indicated by inhibitor studies. The optimal pH value for cysteine proteinases was 5.5, while serine proteinases were optimal at pH 8.0. As a control, cultures of Escherichia coli, the diet of C. elegans, were extracted separately and gave no evidence of overlap with C. elegans ESP. Cross reactivity between the ESP of C. elegans and antibodies raised against the ESP of the equine parasite Strongylus vulgaris indicated antigenic relatedness of a proteic epitope. This is the first study to characterize the ESP of C. elegans and to display its relatedness with that of S. vulgaris.

Molecular diagnosis and equine parasitology

The future implementation of improved and sustainable control strategies for the major equine parasites will be dependent on a greater insight into their basic biology, pathogenicity and epidemiology together with an enhanced ability for accurate diagnosis. This paper will provide a review of the current molecular methods under development for the detection of equine parasites and their application to current scientific questions. In particular, the strongyles are recognised as important pathogens of horses and recent advances made in the study of this parasitic group at the single species level will be addressed. The ribosomal (r)DNA region of the parasite genome has been employed to distinguish between closely related species. Molecular probes designed to this target region were used in combination with PCR technology to allow the identification of individual species within mixed infections. They have been applied to all parasite stages to look at the role of individual species in natural infection, disease and drug resistance. Similar techniques have been developed to detect other equine parasites and these will also be discussed. Further opportunities for employing existing techniques and the need for new diagnostic tools will be highlighted.

Prescription-only anthelmintics—A questionnaire survey of strategies for surveillance and control of equine strongyles in Denmark

In 1999, legislation in Denmark made anthelmintic drugs available only by prescription, and prohibited their use for routine, prophylactic treatment. A questionnaire survey was conducted in 2004 to determine current strategies for surveillance and control of equine strongyles used in Danish equine veterinary practices. Eighty-seven of 170 (51.2%) registered equine veterinary practices responded. Ninety seven percent of the respondents used faecal egg counts for diagnosis and surveillance, and 41% used larval cultures. Logistic regression revealed that the use of larval cultures was positively correlated with numbers of employees ( P = 0.013) and the proportion of equine caseload in the practice ( P < 0.000). Performing faecal egg counts and treating horses was most frequent during spring, summer and early autumn. Veterinary practices made treatment decisions based on cut-off values ranging from 20 to 500 eggs per gram (EPG) faeces. Ages of horses, clinical suspicions of parasitic disease, or requests by the owners were the most important factors in the strategies for faecal sampling. Less commonly, sampling strategies included all horses on the premises and random sampling. Ninety five percent of the respondents reported treating certain groups of horses without prior faecal analysis, including horses with clinical signs of parasitic disease (77%), foals (84%), horses less than 3 years of age (52%), and pregnant mares (51%). The respondents regarded the cyathostomin group as the most prevalent cause of parasitic disease and ill-thrift, followed by large strongyles and Parascaris equorum. Sixty seven percent rotated regularly between drugs, while 11% performed routine screening for anthelmintic resistance. Results of this survey suggest that limiting equine anthelmintics to prescription-only availability has increased the level of strongyle surveillance. Veterinary practitioners play a central role in equine parasite management with indications of a lowered intensity of treatment. However, screening for anthelmintic resistance remains uncommon.

Prevalence of equine gastrointestinal parasites in Western highlands of Oromia

Summary A study was conducted in three selected highland districts of western Oromia, Ethiopia, during the year 2002 –2003 to assess constraints of equine production with emphasis on gastrointestinal parasites. Coprological study (n=388) indicated that overall prevalence of small and large strongyles was (92.8%), Parascaris equorum (17.1%), Dictyocaulus arnifildi (2.6%) and Oxyuris equi (2.1%). Likewise, quantitative coprological study (egg count per gram of feces) (EPG) indicated moderate infection in 29.4%, 49.4% and 38.6%; and severe infection in 37.3%, 28.9% and 31.8% in donkeys, horses and mules, respectively. There was no significant (p>0.05) difference in prevalence rate and EPG across study districts, equine species, and sex of the animals. There was significant difference in prevalence rate and EPG count in different seasons of the year, body condition and age of equines. Therefore, strategic and tactical approaches of parasitic control and further epidemiological investigation of equine diseases are recommended. Key words : GIT parasite, EPG, equine, western highland, Oromia, Ethiopia Prevalence Des Parasites Gastro-Intestinaux Des Equides Dans Les Hauts Plateaux De L\'ouest De L\'oromie En Ethiopie Resume Une etude a ete conduite dans trois districts choisis des hauts plateaux de l\'ouest de l\'Oromie en Ethiopie pendant la periode 2002-2003, afin d\'evaluer les obstacles a la production equine avec un accent particulier sur les parasites gastro-intestinaux. L\'etude coprologique (n=388) a revele que la prevalence globale des petits et gros strongyles etait de 92,8%, Parascaris equorum (17,1%), Dictyocaulus arnifildi (2,6%) et Oxyuris equi (2,1%). De meme, l\'etude coprologique quantitative (nombre d\'oeufs de strongyle par gramme de feces (EPG) a montre une faible infection chez 29,4% ; 49,4% et 38,6%, et chez 37,3% ; 28,9% et 31,8% des ânes, des chevaux et des mulets, respectivement. Il n\'y avait pas de difference significative (p>0,05) quant au taux de prevalence et a l\'EPG entre les districts faisant l\'objet d\'etude, les especes equines et le sexe des animaux ; alors qu\'il y avait une nette difference relative: au taux de prevalence et a l\'EPG entre les differentes saisons de l\'annee, a l\'etat corporel des animaux et a l\'âge des equides. Il est donc recommande d\'adopter des approches strategiques et tactiques de lutte contre les parasites et de mener, par ailleurs, une enquete epidemiologique sur les maladies equines. Mots-cles : Parasite gastro-intestinal, EPG, equin, hauts plateaux de l\'ouest, Oromie, Ethiopie Bull Anim. Hlth. Prod. Afr. Vol. 53 (3) 2005: 161-166

Enzyme-Linked Immunosorbent Assays for Detection of Equine Antibodies Specific toSarcocystis neuronaSurface Antigens

Sarcocystis neurona is the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against total S. neurona parasite antigen, the current gold standard for S. neurona serology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies against S. neurona in horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM.

Babesia caballi and Babesia equi: Implications of host sialic acids in erythrocyte infection

The present study investigated the involvement of host sialic acids in the erythrocyte infection by two equine Babesia parasites, Babesia equi and Babesia caballi. We observed that the in vitro growth of both parasites is influenced by the removal of sialic acids from the surface of equine erythrocytes (RBC). When the parasites were cultured with neuraminidase (Nm, EC 3.2.1.18)-treated RBC, in which α2–3-linked sialic acid residues were removed from four membrane proteins of the RBC, B. caballi showed a significant inhibition of the erythrocyte invasion, while the intracellular development of B. equi seemed to be significantly affected. The possible involvement of host sialic acid in the erythrocyte invasion by B. caballi was also supported by a significant reduction in the parasite growth accompanied by an increased number of extracellular merozoites after the addition of exogenous 3′-sialyllactose (Neu5Acα(2–3)Galβ(1–4)Glc) into the culture. These results suggest that the α2–3-linked sialic acid residues on host RBC play important roles in the erythrocyte infections by B. caballi and B. equi.

Recent developments in research into the Cyathostominae and Anoplocephala perfoliata.

Intestinal helminths are an important cause of equine disease. Of these parasites, the Cyathostominae are the commonest group that infect horses. These nematodes consist of a complex tribe of 51 species, although individual horses tend to harbour 10 or so common species, in addition to a few rarer species. The Cyathostominae can be extremely pathogenic, and high levels of infection result in clinical symptoms ranging from chronic weight loss to colic, diarrhoea and death. As part of their life cycle, immature cyathostomins penetrate the large intestinal wall, where they can enter a state of inhibited larval development. These larvae can exist in this state for months to years, after which they subsequently re-emerge. If larvae re-emerge in large numbers (i.e. several million), severe pathological consequences ensue. The inhibited larvae are also relatively refractory to several of the currently available anthelmintics, so that horses treated previously with anthelmintics can still carry life-threatening burdens of these parasitic stages. Little is known about the cyathostomin larvae during their mucosal phase, and current research efforts are focused on investigating the biology of these stages. Much of the research described here highlights this area of research and details studies aimed at investigating the host immune responses that the mucosal larvae invoke. As part of this research effort, molecular tools have been developed to facilitate the identification of larval and egg stages of cyathostomins. These molecular tools are now proving very useful in the investigation of the relative contributions that individual, common cyathostomin species make to the pathology and epidemiology of mixed helminth infections. At the more applied level, research is also in progress to develop an immunodiagnostic test that will allow numbers of mucosal larvae to be estimated. This test utilises antigen-specific IgG(T) serum antibody responses as markers of infection. As anthelmintic resistance will be the major constraint on the future control of the Cyathostominae, researchers are now actively investigating this area and studies aimed at elucidating the molecular mechanisms of drug resistance are described. Another parasite which has assumed a clinically important role in horses is the tapeworm, Anoplocephala perfoliata. This parasite is prevalent world-wide and has been shown to be a significant cause of equine colic. Because previous methods of estimating the infection intensity of tapeworm were inaccurate, recent research has been directed at developing an immunodiagnostic ELISA for these cestodes. Specific IgG(T) responses to antigens secreted by adult tapeworms have been shown to provide a reasonable indication of infection intensity. An ELISA based on these responses is now commercially available. The steps involved in the development of this ELISA are described here. In addition to these recent advances in research, this review also outlines the principle areas for future research into these important equine parasites.

Controle biológico de helmintos parasitos de animais: estágio atual e perspectivas futuras

O controle biológico é um método desenvolvido para diminuir uma população de parasitas pela utilização de antagonista natural. A administração de fungos nematófagos aos animais domésticos é considerada uma promissora alternativa na profilaxia das helmintíases gastrintestinais parasitárias. Os fungos nematófagos desenvolvem estruturas em forma de armadilhas, responsáveis pela captura e destruição dos estágios infectantes dos nematóides. Os fungos dos gêneros Arthrobotrys, Duddingtonia e Monacrosporium têm demonstrado eficácia em experimentos laboratoriais e no campo no controle de parasitos de bovinos, eqüinos, ovinos e suínos. Diversas formulações fúngicas têm sido avaliadas, no entanto, ainda não há nenhum produto comercial disponível. A associação dos grupos de pesquisa e o envolvimento das indústrias poderão colaborar para o sucesso na implementação desta forma de controle.

Equine cyathostome populations: accuracy of species composition estimations

Historically, surveys of equine parasites either are not quantitative in regard to prevalence and intensities of cyathostome species, or if quantitative, are estimates based on the identification of a very small sample of the population. Commonly 100–200 worms are identified. In the current study cyathostomes from 10 ponies were counted and identified to species in subsets of approximately 200 worms each from 5% aliquots of the large intestine contents until all worms in the aliquot were examined. A mean of 10.9±4.3 species were identified by examining 200 cyathostomes from each animal. This number increased to 25.2±2.6 species when the 5% aliquots were totally examined, indicating that prevalence rates from species with low intensities are probably much greater than previous survey data indicate. A statistical model was used to determine how many worms need to be identified to give a 95% confidence level that all species present are identified.