endoparasite

Papaya latex supernatant has a potent effect on the free-living stages of equid cyathostomins in vitro

Citation

Laura Peachey, Gina L. Pinchbeck, Jacqui. B. Matthews, Faith A. Burden, J.M. Behnke, Jane Hodgkinson. August 2016. Papaya latex supernatant has a potent effect on the free-living stages of equid cyathostomins in vitro. Veterinary Parasitology.

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Publication date: 
1 August 2016
DOI number: 
10.1016/j.vetpar.2016.07.036
Abstract

The control of equid gastrointestinal nematodes in developed countries, in particular the cyathostomins, is threatened by high levels of anthelmintic resistance. In recent years, there has been increasing interest in the evaluation of traditional ‘ethnoveterinary’ medicines as alternatives to chemical anthelmintics. The cysteine proteinases (CPs), a group of enzymes derived from fruits such as papaya (Carica papaya), pineapple (Ananas comosus) and figs (Ficus spp.), have shown good efficacy against adult stages of a range of parasitic nematodes, in vitro and in vivo. The efficacy of CPs against cyathostomins remains to be explored. In this study, the efficacy of a crude preparation of CPs, papaya latex supernatant (PLS), against the free-living stages of cyathostomins was evaluated using two in vitro tests, the egg hatch test (EHT) and the larval migration inhibition test (LMIT). It was demonstrated that PLS had a potent effect in the EHT, with EC-50 values in the range of 0.12-0.22 μM. At concentrations above 6.25 μM the eggs did not develop, below this concentration the L1 developed but they lost integrity of the cuticle upon hatching. These effects were inhibited by pre-incubation of PLS with the CP inhibitor L-trans-epoxysuccinyl-L-leucylamido-(4-guanidino butane) (E64), indicating that CPs were responsible for the anti-parasitic activity. A dose-dependent inhibition of migration of third stage larvae (L3) in the LMIT was demonstrated at higher concentrations of PLS, with EC-50 values in the range of 67.35-106.31 μM. Incubation of PLS with E64 prior to use in the LMIT did not reverse the anti-migratory effect, suggesting that CPs were not responsible for the reduced migration of cyathostomin L3 and that PLS also contains an additional active compound. This is the first report of PLS and/or CPs showing activity against the free-living stages of a parasitic helminth. In addition, it suggests that cyathostomins are highly sensitive to the effects of CPs and further evaluation of their efficacy against parasitic stages and in vivo are strongly indicated.

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Quantifying the effects of individual animal characteristics and climatological factors on faecal worm egg count shedding in donkeys

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Christopher J Corbett, Sandy Love, Giles T. Innocent, Ian McKendrick, Jacqui. B. Matthews, Faith A. Burden, Matthew Denwood. Quantifying the effects of individual animal characteristics and climatological factors on faecal worm egg count shedding in donkeys. Presented at British Society for Parasitology Spring Meeting.

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Date presented: 
Monday 7 April 2014
Abstract

Cyathostomins, the predominant parasitic nematodes of equids, have developed varying degrees of resistance to all three classes of anthelmintic licensed for use in horses. It is essential that the effectiveness of alternative methods of control for these pathogens are quantified, including incorporating climatic data and the commonly advocated practice of removal of faeces from pasture. Here, we obtained monthly faecal worm egg counts (FWEC, n=4,460 individual counts) from 803 donkeys based at The Donkey Sanctuary (Devon, UK). The dataset also included age, sex, field, FWEC history and previous anthelmintic administrations in each individual, as well as the pasture hygiene management method applied in the field where the donkey was grazed. FWEC were analysed alongside local climatic data using a generalised linear mixed model to assess associations between these variables and each observed monthly FWEC. The preferred model was identified using a model selection algorithm based on penalised likelihoods, and associated a 2.1% decrease in FWEC per day with air frost two calendar months ago (p<0.001) and a 38% lower FWEC in groups with twice weekly manual faecal removal compared to those with no faecal removal (p=0.004). Other weather effects, both alone and as interaction terms with the average FWEC of the field were included in the model, alongside individual FWEC history with anthelmintic administration as interaction terms and date as a single term. Our study identifies factors that may be useful as part of on-going predictive modelling based methods of improving targeted selective therapy.

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Clinical trial on the efficacy of moxidectin oral gel formulation on donkeys naturally infected by cyathostominae

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Date presented: 
Saturday 7 February 2015
Abstract

Donkeys and horses share several parasites including the small strongyles, Cyathostominae. Moxidectin (MOX), a compound of macrocyclic lactones, has a wide range of ecto and endoparasitic activity in many species. For horses, MOX is available as oral gel formulation that provides excellent and long-lasting efficacy against nematodes such as large and small strongyles. There is a paucity of data available on the efficacy of anthelmintics used in donkeys (Veneziano et al., 2011). Therapeutics, such as antiparasitic compounds, are often administered to donkeys on the basis of dosage and intervals recommended for horses, because very few drugs have donkey-specific label indications (Grosenbaugh et al., 2011). The objective of the present study was to evaluate the field efficacy and Egg Reappearance Period (ERP) of MOX oral gel up to 84 days at horse dose against natural infection of Cyathostominae in donkeys.

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The evaluation of ethnoveterinary medicines for treating gastrointestinal nematodes in working equids

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Date presented: 
Wednesday 2 July 2014
Abstract

Introduction: Herbal medicines have been used in human and animal medicine for centuries to treat parasitic diseases; few examples have been investigated for genuine anti-parasitic activity. In developing countries access to effective anthelmintic treatment for livestock is often limited by cost, availability and variable quality. Reports of resistance to benzimadazoles in ruminants in Ethiopia serve as a warning that anthelmintic resistance may also be an emerging problem [1,2]. In light of these issues there is increasing interest in plant remedies as alternatives to synthetic anthelmintics. This study used a participatory rural appraisal (PRA) to identify plants with potential anthelmintic activity in the Oromia region of Ethiopia; five plant extracts were shortlisted and tested for efficacy against cyathostomins using in vitro assays. Current attitudes to ethnoveterinary medicine were discussed.

Methods: Focus group discussions with 29 groups of donkey owners from the Oromia region of Ethiopia explored the use of plants to treat GI parasites in livestock. Current attitudes to herbal medicines were discussed and recorded using thematic analysis. Plants of interest were collected and identified at the National Herbarium, Addis Ababa, Ethiopia. Plants were shortlisted for in vitro tests based on four criteria; ranking in the PRA, supportive literature, no evidence of toxicity and availability. Hydro-alcoholic extraction of dried plant material from shortlisted species was performed. The efficacy of extracts was evaluated in the egg hatch assay (EHA) using cyathostomin eggs recovered from the faeces of donkeys at the Donkey Sanctuary, UK. Dose response curves were produced and ED-50 values calculated using probit analysis.

Results: The focus groups identified 21 plants used as anthelmintics in livestock. A general move away from traditional medicines in the younger generation was observed, although when asked if they would use plants in future many would consider this if they had been tested scientifically and were approved by professionals. The five plants shortlisted for in vitro analysis were Acacia nilotica, Cucumis prophetarum, Rumex abysinnicus, Vernonia amygdalinia and Withania somnifera. Three showed efficacy in the EHA; Acacia nilotica, Cucumis prophetarum and Rumex abysinnicus , with EC-50 values of 0.7, 1.1 and 1.3mg/ml respectively.

Conclusion: Three out of five of the plants identified in the PRA showed efficacy in vitro suggesting that plant remedies used by livestock owners in the Oromia region of Ethiopia may contain compounds with genuine anthelmintic activity. Evaluation of current attitudes suggests that plant remedies are not used unless there is no other option, but that they would be considered should scientific evidence of efficacy and safety be presented to them by animal health professionals [3]. It is therefore essential that a randomised controlled trial is used to verify whether in vitro anthelmintic activity can be translated in vivo and thus whether the plants identified in this study have potential as safe alternatives to synthetic anthelmintic drugs. This study has highlighted that local practices pertaining to the health of working equids are a rich source of information that may help to inform sustainable and effective treatment strategies in future.

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Anthelmintic control of lungworm in donkeys

Citation

Hilary Clayton, Andrew F. Trawford. Anthelmintic control of lungworm in donkeys. Equine Veterinary Journal. 13:3. 192-194.

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Volume: 
13
Issue: 
3
Page numbers: 
192-194
DOI number: 
10.1111/j.2042-3306.1981.tb03483.x
Abstract

A field study was designed to investigate the re-establishment of patent lungworm infections in donkeys following an anthelmintic treatment regime which was effective against Dictyocaulus arnfieldi. In April 1979 faecal samples from 259 donkeys were examined and each animal classified as a negative, low positive or high positive excretor of lungworm larvae. During the summer the control group of 126 donkeys showed an increase in the number of excretors from 80 per cent in April to 91 per cent in October. At the same time there was a rise in the faecal larval output of individual animals so that by October 59 per cent were classified as high positive compared with only 20 per cent in April. The treated group of 133 donkeys received 3.5 g mebendazole daily for 5 days during April and as a result the number of excretors fell from 66 per cent pretreatment to 23 per cent one month after treatment. Despite exposure to infected pastures throughout the summer this figure was maintained at a comparatively low level and by October patent infections had been re-established in only 15 per cent of the donkeys that were negative after treatment.

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The evaluation of African and UK bioactive plant extracts for the control of equid gastrointestinal nematodes

Citation

Laura Peachey, Gina L. Pinchbeck, Claire Scantlebury, Gebre Tefera, Mulugeta Getachew, D. Etana, Faith A. Burden, Andrew F. Trawford, Jacqui. B. Matthews, Jane Hodgkinson. The evaluation of African and UK bioactive plant extracts for the control of equid gastrointestinal nematodes. Presented at International Conference on Equine Infectious Diseases IX. (21 October - 26 October 2012). Kentucky, USA.

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Date presented: 
Tuesday 23 October 2012
Abstract

In the developed world the control of equid gastrointestinal (GI) nematodes, in particular cyathostomins, is increasingly challenging due the threat of anthelmintic resistance. In developing countries such as Ethiopia despite high parasite burdens, access to genuine anthelmintic treatment is limited. In both situations there is a need for alternative treatment and management regimens for effective parasite control and consequently there has been increasing interest in the use of bioactive plant extracts (BPEs) [1]. This study identified candidate plants in the UK and Ethiopia and evaluated their in vitro efficacy against cyathostomin populations derived from donkeys. A participatory rural appraisal (PRA) approach was used to identify five ethnoveterinary medicines for use in donkeys in Ethiopia. In the UK three plants were identified following extensive review of literature citing efficacy against GI nematodes of other host species and two extracts were provided courtesy of Prof Jerzy Behnke, University of Nottingham. Hydro-alcoholic extraction of dried plant material was carried out for the eight extracts prior to reconstitution in both water and DMSO. Efficacy of each extract was evaluated by egg hatch assay (EHA) and larval migration assay (LMA) using eggs and larvae recovered from the faeces of donkeys at the Donkey Sanctuary, UK. Dose response curves were produced and ED-50 values were calculated using probit analysis. Of the five Ethiopian plant extracts tested, four showed efficacy in the EHA and/or LMA. The two most efficacious were Acacia nilotica and Rumex abyssinicus in the EHA with ED-50 values of 0.72mg/ml and 1.29mg/ml respectively. Of the five UK extracts four showed efficacy in the EHA and/or LMA. The two most efficacious were Carica papaya (papaya) in the LMA and Allium sativum (garlic) in the EHA with ED-50 values of 18.9µM and 0.65mg/ml respectively. The two BPEs most efficacious in vivo for Ethiopia and the UK are to be carried forward to in vivo trials. This study has demonstrated in vitro efficacy of nine plant extracts against cyathostomins. There is evidence in the literature that these plant extracts show efficacy both in vitro and in vivo against GI nematodes in other species. Therefore these results have identified potential alternatives to synthetic anthelmintics for the treatment of cyathostomins that require further investigation.

[1] Githiori JB, Athanasiadou S, Thamsborg SM. Use of plants in novel approaches for control of gastrointestinal helminths in livestock with emphasis on small ruminants. Vet Para 2006;139, 308–320.

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