Evaluation of efficacy expectations for novel and non-chemical helminth control strategies in ruminants

In vivo anthelmintic activity of Combretum mucronatum schumach & Thonn leaf extract against Haemonchus contortus in goats

Parasitic infections with gastrointestinal nematodes are a serious problem for the health and welfare of domestic animals and negatively affect the economics of animal production. Haemonchus contortus is a haematophagous nematode of small ruminants responsible for significant mortality and morbidity. In addition, the widespread resistance to synthetic anthelmintic drugs emphasizes the urgent need of alternative treatment options against haemonchosis. This work aims to investigate the anthelmintic activity of an hydroethanolic Combretum mucronatum leaf extract (CMLE) against Haemonchus contortus in goats. Goats were artificially infected with 3500 third-stage larvae of H. contortus, and 21 days later, treated with CMLE (1000, 500, 250 mg/kg) for 4 consecutive days. Different parameters such as faecal egg count reduction, weight and haematocrit were monitored during the experimental period. The number of eggs per gram of faeces (EPG) was concentration-depended lower and significantly reduced compared to the untreated control (p < 0.0001). The effect of the highest CMLE dose (4 ×1000 mg/kg body weight) was similar to the effect of albendazole (1 ×5 mg/kg of body weight). The ED50 and ED90 values calculated were 189.17 and 392.33 mg/kg body weight respectively. ED50 and ED90 values were time-dependent. Moreover, CMLE improved haematocrit and weight of goats in dose-dependent and time-dependent manner. These results showed that CMLE could be used for haemonchosis treatment in small ruminants.

Effect of pomegranate (Punica granatum) anthelmintic treatment on milk production in dairy sheep naturally infected with gastrointestinal nematodes

Anthelmintic drug resistance has proliferated across Europe in sheep gastrointestinal nematodes (GINs). Sheep welfare and health are adversely impacted by these phenomena, which also have an impact on productivity. Finding alternatives for controlling GINs in sheep is thus of utmost importance. In this study, the anthelmintic effectiveness (AE) of a Calabrian ethnoveterinary aqueous macerate based on Punica granatum (whole fruits) was assessed in Comisana pregnant sheep. Furthermore, an examination, both qualitative and quantitative, was conducted on milk. Forty-five sheep were selected for the investigation. The sheep were divided by age, weight, physiological state (pluripara at 20 days before parturition), and eggs per gram of feces (EPG) into three homogeneous groups of 15 animals each: PG received a single oral dosage of P. granatum macerate at a rate of 50 mL per sheep; AG, treated with albendazole, was administered orally at 3.75 mg/kg/bw; and CG received no treatment. Timelines were as follows: D0, treatments, group assignment, fecal sampling, and AE assessment; D7, D14, D21, fecal sampling, and AE evaluation. The FLOTAC technique was used to evaluate the individual GIN fecal egg count (FEC) using a sodium chloride flotation solution (specific gravity = 1.20) and 100 × (1-[T2/C2]) as the formula for evaluating FEC reduction. Following the lambs' weaning, milk was collected on the following days (DL) in order to quantify production: DL35, DL42, DL49, DL56, DL63, DL70, DL77, and DL84. The amount of milk produced by every animal was measured and reported in milliliters (ml) for quantitative evaluations. Using MilkoScan TM fT + foss electric, Denmark, the quality of the milk (casein, lactose, protein concentration, and fat, expressed as a percentage) was assessed. The macerate demonstrated a considerable AE (51.8%). Moreover, its use has resulted in higher milk production rates quantitatively (15.5%) and qualitatively (5.12% protein, 4.12% casein, 4.21% lactose, and 8.18% fat). The study showed that green veterinary pharmacology could be the easiest future approach to counteracting anthelmintic resistance in sheep husbandry.

Mucosal Immunity of Major Gastrointestinal Nematode Infections in Small Ruminants Can Be Harnessed to Develop New Prevention Strategies

Gastrointestinal parasitic nematode (GIN) infections are the cause of severe losses to farmers in countries where small ruminants such as sheep and goat are the mainstay of livestock holdings. There is a need to develop effective and easy-to-administer anti-parasite vaccines in areas where anthelmintic resistance is rapidly rising due to the inefficient use of drugs currently available. In this review, we describe the most prevalent and economically significant group of GIN infections that infect small ruminants and the immune responses that occur in the host during infection with an emphasis on mucosal immunity. Furthermore, we outline the different prevention strategies that exist with a focus on whole and purified native parasite antigens as vaccine candidates and their possible oral-nasal administration as a part of an integrated parasite control toolbox in areas where drug resistance is on the rise.

Research on the Control of Gastrointestinal Strongyles in Sheep by Using Lotus corniculatus or Cichorium intybus in Feed

The general practice of sheep farmers in gastrointestinal helminth control is based on the use of commercial drugs, making chemoresistance very common. Considering this, our study focused on the biological control of gastrointestinal parasitism using high-tannin plant hay. Three groups of 30 animals each were formed. The control group was additionally fed meadow hay, while the other two groups received chicory (group 2) and bird's foot trefoil hay (group 3). The number of gastrointestinal strongyle eggs, shed through faeces (EPG), was surveyed for 28 days for all animals. The amounts of total tannins for meadow, chicory, and Lotus corniculatus hay supplements were 13.92 mg/g, 78.59 mg/g, and 94.43 mg/g, while their condensed tannin contents were 2.58 mg/g, 29.84 mg/g, and 15.94 mg/g, respectively. Compared to experimental day 0, there was an increase in EPG of 80.83% in the control group, a decrease of 24.72% in group 2, and a 20% decrease in group 3, by day 28. The p-value was <0.05 between group 1 and the other groups, showing significant differences between the control and experimental groups. The decrease in EPG rates in the experimental groups compared to the control group demonstrates an antiparasitic effect of Lotus corniculatus and chicory.

Antiparasitic Tannin-Rich Plants from the South of Europe for Grazing Livestock: A Review

Internal parasites are one of the main causes of health threats in livestock production, especially in extensive livestock farming. Despite the environmental toxic effects (loss of dung beetles, biodiversity, and other issues) and resistance phenomenon derived from their prolonged use, anti-parasitic chemical pharmaceuticals are frequently used, even in organic farming. Such a situation within the context of climate change requires urgent exploration of alternative compounds to solve these problems and apparent conflicts between organic farming objectives regarding the environment, public health, and animal health. This review is focused on some plants (Artemisia spp., Cichorium intybus L., Ericaceae family, Hedysarum coronarium L., Lotus spp., Onobrychis viciifolia Scop.) that are well known for their antiparasitic effect, are voluntarily grazed and ingested, and can be spontaneously found or cultivated in southern Europe and other regions with a Mediterranean climate. The differences found between effectiveness, parasite species affected, in vitro/in vivo experiments, and active compounds are explored. A total of 87 papers where antiparasitic activity of those plants have been studied are included in this review; 75% studied the effect on ruminant parasites, where gastrointestinal nematodes were the parasite group most studied (70%), and these included natural (31%) and experimental (37%) infections.

Investigation of Parasitic Infection in Crocodile Lizards (Shinisaurus crocodilurus) Using High-Throughput Sequencing

The highly endangered crocodile lizard (Shinisaurus crocodilurus) continues to be impacted by disease, especially in captive breeding populations. In this paper, based on high-throughput sequencing, we investigated parasitic infections in captive and wild crocodile lizard populations in the Daguishan National Nature Reserve and Guangdong Luokeng Shinisaurus crocodilurus National Nature Reserve. The results show that the overall parasitic infection rate in crocodile lizards was 33.33% (23/69). Four parasite genera were detected, including Eimeria, Cryptosporidium, Nematopsis, and Acanthamoeba, with infection rates of 15.94% (11/69), 17.39% (12/69), 7.25% (5/69), and 4.35% (3/69), respectively. Significant differences in the infection rate were found between the different parasite species (χ2 = 8.54, p < 0.05, chi-squared test). The parasitic infection rates in the captive and wild populations were 39.29% (22/56) and 7.69% (1/13), respectively, which were significantly different (p < 0.05, Fisher’s exact test). However, no significant differences in the infection rates of the four parasite genera were found between the captive and wild populations (p > 0.05, Fisher’s exact test). The parasitic infection rates in Daguishan and Luokeng were 34.09% (15/44) and 32.00% (8/25), respectively, which were not significantly different (p > 0.05, Fisher’s exact test). However, significant differences in terms of species were found in the two reserves (p < 0.01, Fisher’s exact test). Only Cryptosporidium infection showed a significant difference between the two regions (p < 0.01, Fisher’s exact test). Our results suggest that captive crocodile lizards are more susceptible to parasitic diseases than wild crocodile lizards and that Cryptosporidium infection varies by geographical region. This study provides basic information about the parasites of endangered crocodile lizards, as well as a reference for disease control and conservation.

Antifilarial Activity of the Methanolic Extract of Indigofera tinctoria (Fabaceae) on Bovine Parasites (Onchocerca ochengi)

Onchocerciasis is a major public health problem caused by Onchocerca volvulus parasite and transmitted to humans via black flies (simulium) bites. The control of onchocerciasis relies much on the use of the chemical drug ivermectin, which is only effective against microfilariae and has led to drug resistance. This study was carried out to assess the in vitro antifilarial activity of methanolic extract of Indigofera tinctoria and its most active fractions on adult male O. ochengi worm, the closest model to O. volvulus, after 48 h and 72 h of treatment. Worms' viability was determined biochemically by MTT/formazan colorimetry assay. The promising plant extract's acute and subacute oral toxicity were evaluated on both mice and rats. The result revealed a highest antifilarial activity of the methanolic extract (LC50 = 12.28 μg/mL) compared to ivermectin (LC50 = 26.50 μg/mL) after 72 h of treatment. Out of the eight (08), chromatographic fractions screened, only three (03) fractions (C, F, and G) revealed the highest anti-Onchocerca activity after 72 h of treatment. An oral administration of the plant extract at a single dose of 2000 mg/kg did not produce any toxicity in mice. After repeated daily administration of methanolic extract of I. tinctoria (250 mg/kg, 500 mg/kg, and 1000 mg/kg) for 28 days, no significant changes in body weight, biochemical, and haematological parameters was observed. Histopathological examination of organs did not reveal any sign of alteration. The phytochemical analysis of the methanolic extract of I. tinctoria revealed the presence of various phenolic compounds. Therefore, this study demonstrated the potential antifilarial activity of Indigofera tinctoria and offered an alternative to treating onchocerciasis. Moreover, further studies could be developed in promising new antifilarial sources of the isolated compound and in vivo antifilarial activity of Indigofera tinctoria in the animal model needs to be studied.

Quantitative estimation of total tannin, alkaloid, phenolic, and flavonoid content of the root, leaf, and whole plant of Byttneria herbacea Roxb

Background

Byttneria herbacea Roxb., family Sterculiaceae, commonly called as 'Samarakhai' in local Odia language, is one of the reputed folklore medicinal herb. Its roots, leaves, and whole plant parts are reported for traditional use in the management of dysentery, sores, cuts, wounds, cholera, leucorrhoea, fractures, and sprains.

Aim

The aim of the present work was to assess the total tannin content, total alkaloid content (TAC), total phenolic content (TPC), and total flavonoid content (TFC) in root, leaf, and whole plant of B. herbacea.

Materials and methods

The amount of total tannins was analyzed using titrimetric method and total alkaloids by gravimetrical method. TPC was measured using Folin-Ciocalteu's method and calculated as gallic acid equivalents and the amount of total flavonoids by aluminum chloride colorimetric method and calculated as chrysin equivalents.

Results

Tannin content was found maximum in the leaf (8.148% w/w) followed by whole plant (3.886% w/w) and root (1.553% w/w); similarly, TAC in the leaf (2.306% w/w) was more than those in root (0.814% w/w) and whole plant (1.319% w/w). The TPC of the methanolic extract of root (372.33 ± 14.29 mg/g) was more than whole plant (267.33 ± 7.63 mg/g); The TFC of the methanolic extract of leaf (620 ± 50 mg/g) was found maximum followed by root (553.33 ± 28.86 mg/g) and whole plant (536.66 ± 28.86 mg/g).

Conclusion

The result of study emphasized presence of tannin, alkaloid, phenol, and flavonoid contents in the root, leaf, and whole plant of B. herbacea where the leaf was found to be richest source.

Safety and efficacy of BioWorma® (Duddingtonia flagrans NCIMB 30336) as a feed additive for all grazing animals

Following a request from the European Commission, the EFSA Panel on Additives and products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of BioWorma® (Duddingtonia flagrans NCIMB 30336) when used as a zootechnical feed additive for all grazing animals. Duddingtonia flagrans belongs to a group of nematophagous fungi that physically entrap nematodes through an adhesive hyphal net. The additive contains the fungus in the form of chlamydospores and is intended to control pathogenic nematodes on pasture, with subsequent benefits for grazing animals. No conclusions could be drawn on the safety for the target species due to lack of data. ■■■■■ As it is not possible to exclude the presence of secondary metabolites (other than flagranones) produced during fermentation and their potential carry-over into animal products, safety for the consumer could not be established. The Panel concluded that the additive is not irritant to skin and eyes but is irritant to the respiratory tract and a respiratory sensitiser. No conclusion could be drawn on its skin sensitisation potential. Since D. flagrans is a naturally inhabiting soil organism of world-wide distribution, the Panel considered that use of an additive based on this organism does not pose a risk for the environment under the intended conditions of use. The strain under application reduced the number of parasitic nematodes on pasture to the benefit of grazing animals when used at the recommended application rate of 3 × 104 chlamydospores/kg bodyweight and day.

In vitro efficacy of Elephantorrhiza elephantina root extracts against adult Paramphistomum cervi in goats

Elephantorrhiza elephantina is a medicinally important plant whose roots are used to control gastrointestinal parasites in goats. The use of plant-based anthelmintics as potential alternatives to synthetic anthelmintics in controlling gastrointestinal worms in ruminants is a promising area of research. The study was carried out to ascertain the efficacy of E. elephantina in controlling goat trematodes. Standard procedures were used to quantify the phytochemicals in the water, ethanol and methanol root extracts of E. elephantina. The quantitative phytochemical analysis revealed that alkaloids (93.24 ± 1.68%), condensed tannins (450.52 ± 0.15 mg CE/g), flavonoids (803.93 ± 0.13 mg QE/g), phenols (476.11 ± 0.37 mg GAE/g) and saponins (83.28 ± 1.72%) were present in E. elephantina root extracts. Paramphistomum cervi adult worms recovered from the rumen of freshly slaughtered goats were used. In vitro screening of ethanol, methanol and water extracts of E. elephantina for potential anthelmintic activity against adult P. cervi worm motility showed time and dose-dependent significant effects. Ethanol extracts showed a highly significant (P < 0.05) inhibition of motility (86.67 and 96.67%) at concentrations 7.5 and 15 mg/mL respectively, after 12 h of treatment, while methanol and water extracts exhibited a significant (P < 0.05) inhibition of motility (96.67 and 66.67% respectively) at concentration of 15 mg/mL 16 h post-exposure. Our findings confirm the efficacy of E. elephantina in controlling goat trematodes.

Sustainable Approaches to Parasite Control in Ruminant Livestock

It is increasingly difficult to manage and control gastrointestinal nematode parasites in pasture-based ruminant livestock operations because of the high prevalence of anthelmintic resistance. Anthelmintics should be combined with alternative forms of control. Sustainable tools include copper oxide wire particles and condensed tannin-rich plants, which target primarily Haemonchus contortus in small ruminants. Nematophagous fungi reduce larvae on pasture and target nematode larvae in feces of most livestock species. In addition, and perhaps most importantly, genetic selection focuses on parasite resistance. Producers should use as many tools as possible to minimize the need for pharmaceutical interventions and optimize animal production.

Ellagitannins Inhibit the Exsheathment of Haemonchus contortus and Trichostrongylus colubriformis Larvae: The Efficiency Increases Together with the Molecular Size

Worldwide, parasitic gastrointestinal nematodes continue to threaten animal health, welfare, and production in outdoor breeding systems of small ruminants. For more than 50 years, the control of these parasitic worms has relied on the use of commercial synthetic anthelmintics. However, anthelmintic resistance in worm populations is nowadays widespread and requires novel solutions. The use of tannin-rich plants has been suggested as an alternative to synthetic anthelmintics to control gastrointestinal nematodes. The majority of previous studies have focused on the activity of proanthocyanidins (syn condensed tannins), and less is known about ellagitannins. In this study, the effects of 30 structurally unique ellagitannins on the exsheathment of third-stage infective larvae were examined on Haemonchus contortus and Trichostrongylus colubriformis by the in vitro larval exsheathment inhibition assay. Ellagitannins were found to be promising natural anthelmintics as they showed direct inhibition on larval exsheathment for both nematode species. In general, ellagitannins were more efficient at inhibiting the exsheathment of H. contortus larvae than those of T. colubriformis. The efficiency of inhibition increased as the degree of oligomerization or the molecular weight of the ellagitannin increased. Otherwise, we found no other structural features of ellagitannins that significantly affected the anthelmintic activity on the third-stage infective larvae. The effective concentrations were physiologically relevant and should be achievable in the gastrointestinal tract also in in vivo conditions.

Transcriptome analysis reveals molecular anthelmintic effects of procyanidins in C. elegans

Worldwide, more than 1 billion people are affected by infestations with soil-transmitted helminths and also in veterinary medicine helminthiases are a severe threat to livestock due to emerging resistances against the common anthelmintics. Proanthocyanidins have been increasingly investigated for their anthelmintic properties, however, except for an interaction with certain proteins of the nematodes, not much is known about their mode of action. To investigate the anthelmintic activity on a molecular level, a transcriptome analysis was performed in Caenorhabditis elegans after treatment with purified and fully characterized oligomeric procyanidins (OPC). The OPCs had previously been obtained from a hydro-ethanolic (1:1) extract from the leaves of Combretum mucronatum, a plant which is traditionally used in West Africa for the treatment of helminthiasis, therefore, also the crude extract was included in the study. Significant changes in differential gene expression were observed mainly for proteins related to the intestine, many of which were located extracellularly or within cellular membranes. Among the up-regulated genes, several hitherto undescribed orthologues of structural proteins in humans were identified, but also genes that are potentially involved in the worms' defense against tannins. For example, T22D1.2, an orthologue of human basic salivary proline-rich protein (PRB) 2, and numr-1 (nuclear localized metal responsive) were found to be strongly up-regulated. Down-regulated genes were mainly associated with lysosomal activity, glycoside hydrolysis or the worms' innate immune response. No major differences were found between the groups treated with purified OPCs versus the crude extract. Investigations using GFP reporter gene constructs of T22D1.2 and numr-1 corroborated the intestine as the predominant site of the anthelmintic activity. The current findings support previous hypotheses of OPCs interacting with intestinal surface proteins and provide the first insights into the nematode's response to OPCs on a molecular level as a base for the identification of future drug targets.

Medicinal plant extracts and plant-derived polyphenols with anthelmintic activity against intestinal nematodes

Covering: 2001 up to the end of 2016Polyphenols comprise a structurally diverse class of natural products. As the development of new anthelmintic drugs against soil-transmitted helminthiases is an urgent need and polyphenols are widely used in the treatment of nematode infections in traditional medicine and modern science, we summarize the state of knowledge in the period of mainly 2001 up to the end of 2016 on plant extracts with known polyphenolic composition and of defined polyphenols, mainly from the classes of condensed and hydrolysable tannins, flavonoids, and phenylpropanoids. The diverse biological activity against different helminths and the underlying mechanisms are reviewed.

Diagnosis, Treatment and Management of Haemonchus contortus in Small Ruminants

Haemonchus contortus is a highly pathogenic, blood-feeding nematode of small ruminants, and a significant cause of mortalities worldwide. Haemonchosis is a particularly significant threat in tropical, subtropical and warm temperate regions, where warm and moist conditions favour the free-living stages, but periodic outbreaks occur more widely during periods of transient environmental favourability. The clinical diagnosis of haemonchosis is based mostly on the detection of anaemia in association with a characteristic epidemiological picture, and confirmed at postmortem by the finding of large numbers of H. contortus in the abomasum. The detection of impending haemonchosis relies chiefly on periodic monitoring for anaemia, including through the 'FAMACHA' conjunctival-colour index, or through faecal worm egg counts and other laboratory procedures. A range of anthelmintics for use against H. contortus is available, but in most endemic situations anthelmintic resistance significantly limits the available treatment options. Effective preventative programmes vary depending on environments and enterprise types, and according to the scale of the haemonchosis risk and the local epidemiology of infections, but should aim to prevent disease outbreaks while maintaining anthelmintic efficacy. Appropriate strategies include animal management programmes to avoid excessive H. contortus challenge, genetic and nutritional approaches to enhance resistance and resilience to infection, and the monitoring of H. contortus infection on an individual animal or flock basis. Specific strategies to manage anthelmintic resistance centre on the appropriate use of effective anthelmintics, and refugia-based treatment schedules. Alternative approaches, such as biological control, may also prove useful, and vaccination against H. contortus appears to have significant potential in control programmes.

Chemical Structures of Plant Hydrolyzable Tannins Reveal Their in Vitro Activity against Egg Hatching and Motility of Haemonchus contortus Nematodes

The use of synthetic drugs against gastrointestinal nematodes of ruminants has led to a situation where resistance to anthelmintics is widespread, and there is an urgent need for alternative solutions for parasite control. One promising approach is to use polyphenol-rich bioactive plants in animal feeds as natural anthelmintics. In the present work, the in vitro activity of a series of 33 hydrolyzable tannins (HTs) and their hydrolysis product, gallic acid, against egg hatching and motility of L1 and L2 stage Haemonchus contortus larvae was studied. The effect of the selected compounds on egg and larval structure was further studied by scanning electron microscopy. The results indicated clear relationships between HT structure and anthelmintic activity. While HT size, overall flexibility, the types and numbers of functional groups, together with the linkage types between monomeric HTs affected the activity differently, the optimal structure was found with pentagalloylglucose.

Plants of the Cerrado naturally selected by grazing sheep may have potential for inhibiting development of Haemonchus contortus larva

Plant species naturally selected by sheep grazing in the Cerrado region of Brazil were assessed in vitro for activity against Haemonchus contortus. One year of observations showed the plant families in the region exhibiting greatest richness to be Fabaceae, Rubiaceae, Malpighiaceae, Bignoniaceae, Myrtaceae, and Annonaceae. Nine species commonly selected by grazing sheep showed variation in the selectivity index with respect to the dry and rainy seasons. Coproculture was conducted in five replicates of 11 treatments: ivermectin, distilled water, or dehydrated leaves of nine selected plant species administered at 333.3 mg g(-1) fecal culture. The dried powder of Piptadenia viridiflora and Ximenia americana leaves significantly reduced the number of infective larvae compared to the distilled water control. These species showed efficacy of over 85 % despite low concentrations of proanthocyanidin. High-performance liquid chromatography analyses of extracts of these plants showed major peaks of UV spectra characteristic of flavonoids. Those naturally selected plant species with high antihelminthic efficacy show promise for use in diet as an alternative control of H. contortus in sheep.

Isolation and characterization of the nematophagous fungus Arthrobotrys conoides

The spread of organic farming and the development of resistance to anthelmintics by parasites, especially in small ruminants, have necessitated the search for alternative methods of nematode control. Biological control using nematophagous fungi is one option; however, few studies have been conducted with native strains. The present study was divided into two phases. In the first phase, we aimed to isolate, identify, and assess the in vitro predatory activity of nematophagous fungi that had been isolated on Trichostrongylidae third-instar larvae. In the second phase, the isolate with superior predatory activity in vitro was molecularly characterized, and its morphological plasticity was observed using scanning electron microscopy (SEM) on Haemonchus third-instar larvae. Of the 56 soil samples from different regions of Paraná State, Brazil, 57 fungal strains were recovered, of which four exhibited predatory activity. Two pure isolates were obtained: the CED and LIN strains. After demonstrating 96.35 % predatory activity for the CED strain, this strain was selected and characterized using molecular criteria by sequencing the rDNA internal transcribed spacer and was identified as Arthrobotrys conoides (GenBank ID: JN191309). Morphological patterns in this strain during the interaction between the fungus and the nematode were revealed by SEM, in which two extensions of the infection bulb that was used to pierce the nematode's cuticle were clearly visible.

Manipulating small ruminant parasite epidemiology through the combination of nutritional strategies

It is increasingly being recognized that non-chemical parasite control strategies may need to be combined to control more effectively gastrointestinal parasitism, result in resilient production systems and reduce reliance on anthelmintics. Here, we consider if and how metabolizable protein (MP) supplementation and anti-parasitic plant secondary metabolites (PSM) may modulate parasite epidemiology through intervention in pasture contamination, development of infection on pasture and larval challenge as target processes. We then propose that combining two or more non-chemical parasite control strategies may have additive effects on host resistance, especially if the individual strategies target different drivers of parasite epidemiology, different processes in the parasite life cycle or different phases of acquired immunity to parasites. This epidemiological framework is used to review recent findings on combining maternal MP supplementation and grazing the PSM-rich bioactive forage chicory as an example of combining nutritional treatments to manipulate parasite epidemiology in a temperate production system. In the absence of available data for combined nutritional strategies in tropical production systems, we make predictions on the consequences of combining such strategies in these systems. We conclude that currently published studies on combining nutritional strategies under temperate conditions show potential to improve additively host resilience and reduce reliance on anthelmintics; however, effects on epidemiology have to date not shown the additive results hypothesized. The framework developed may assist further in evaluating combined (nutritional) strategies to manipulate parasite epidemiology.

Anthelmintic resistance in sheep farms: update of the situation in the American continent

The present paper reviews the frequency of anthelmintic resistance in sheep farms in different countries of the American continent and describes some aspects that might influence the trend in sheep farms. The situation of anthelmintic resistance in sheep farms has been explored mainly in south of the continent (Argentina, Brazil and Uruguay) where sheep farming is an important industry. In those three countries, as well as in Paraguay, the first comprehensive surveys of anthelmintic resistance were performed among countries in the continent, which showed evidence of high frequency of sheep farms with anthelmintic resistance. Today, it is common to find sheep flocks with multiple-resistant worms. In North and Central America, a similar situation has been reported in sheep farms in the south of the United States of America, parts of Mexico and Costa Rica. On the other hand, other areas of the continent show low frequency of farms with anthelmintic resistance. From many areas no results have been published regarding situation on anthelmintic resistance or, alternatively, published results have received limited dissemination. Although the diagnosis of anthelmintic resistance is important for decision making of helminth management/control at the farm level, this is still an aspiration rather than a reality. For decades, researchers working on anthelmintic resistance in the American continent have expressed the need to change farmers' attitudes towards anthelmintic drugs. A common advice has been to check the anthelmintic drug efficacy regularly and reduce the dependence on these with alternative control measures. In spite of such advice, the challenge to stop/delay the advancement of anthelmintic resistance against the available anthelmintic drugs is still present. The evidence suggests that anthelmintic resistance is a growing phenomenon in the American continent. The situation described might be the tip of the iceberg, as anthelmintic resistance is still largely under-diagnosed. Hence, a different approach to tackle the advancement of anthelmintic resistance in sheep farms must be found. Awareness of farmers on the importance of diagnosis of anthelmintic resistance is not enough. Technical support schemes that provide the diagnostic service cheaply and timely must be implemented together with the research aiming at the adoption of control methods to reduce the dependence on conventional anthelmintic drugs. Unless these elements are readily available for producers, the negative consequences of anthelmintic resistance on sheep farming in America will continue to worsen with time.

Livestock Helminths in a Changing Climate: Approaches and Restrictions to Meaningful Predictions

Climate change is a driving force for livestock parasite risk. This is especially true for helminths including the nematodes Haemonchus contortus, Teladorsagia circumcincta, Nematodirus battus, and the trematode Fasciola hepatica, since survival and development of free-living stages is chiefly affected by temperature and moisture. The paucity of long term predictions of helminth risk under climate change has driven us to explore optimal modelling approaches and identify current bottlenecks to generating meaningful predictions. We classify approaches as correlative or mechanistic, exploring their strengths and limitations. Climate is one aspect of a complex system and, at the farm level, husbandry has a dominant influence on helminth transmission. Continuing environmental change will necessitate the adoption of mitigation and adaptation strategies in husbandry. Long term predictive models need to have the architecture to incorporate these changes. Ultimately, an optimal modelling approach is likely to combine mechanistic processes and physiological thresholds with correlative bioclimatic modelling, incorporating changes in livestock husbandry and disease control. Irrespective of approach, the principal limitation to parasite predictions is the availability of active surveillance data and empirical data on physiological responses to climate variables. By combining improved empirical data and refined models with a broad view of the livestock system, robust projections of helminth risk can be developed.

In vitro and in vivo efficacy of aqueous extract of Caryocar brasiliense Camb. to control gastrointestinal nematodes in sheep

A major problem faced in sheep rearing has been the rapid acquisition of anthelminthic-resistant populations of gastrointestinal nematodes. In the search for alternatives, aqueous extract of the peel of Caryocar brasiliense was evaluated for larval development inhibition, egg-hatching inhibition, and fecal nematode egg count reduction in sheep. For in vivo analysis, the doses were calculated according to a 10% lethal dose derived from acute toxicity tests in mice, and the efficacy was evaluated for two periods following oral administration of the extract. Egg-hatching inhibition at concentrations of 15 and 7.5 mg/ml was significantly higher than observed in negative controls with distilled water. For larval development inhibition, all concentrations showed anthelminthic activity significantly higher than controls and were not significantly different from ivermectin treatment. The LC(90) of larval development inhibition was 53.19 mg/ml. In vivo analysis for first and second weeks after treatment found 32.2% and 33% anthelminthic efficacy, respectively.

Targeted flock/herd and individual ruminant treatment approaches

In Europe, most nematodoses are subclinical involving morbid rather than mortal effects and control is largely achieved using anthelmintics. In cattle, the genera most associated with sub-optimal performance are Ostertagia and Cooperia whereas in sheep and goats, subclinical losses are most often caused by Teladorsagia and Trichostrongylus. In some regions, at certain times, other species such as Nematodirus and Haemonchus also cause disease in sheep and goats. Unfortunately, anthelmintic resistance has now become an issue for European small ruminant producers. One of the key aims of the EU-funded PARASOL project was to identify low input and sustainable approaches to control nematode parasites in ruminants using refugia-based strategies. Two approaches to optimise anthelmintic treatments in sheep and cattle were studied; targeted treatments (TT) - whole-group treatments optimised on the basis of a marker of infection e.g. faecal egg count (FEC), and targeted selected treatment (TST) - treatments given to identified individuals to provide epidemiological and/or production benefits. A number of indicators for TT and TST were assessed to define parasitological and production-system specific indicators for treatment that best suited the regions where the PARASOL studies were conducted. These included liveweight gain, production efficiency, FEC, body condition score and diarrhoea score in small ruminants, and pepsinogen levels and Ostertagia bulk milk tank ELISA in cattle. The PARASOL studies confirmed the value of monitoring FEC as a means of targeting whole-flock treatments in small ruminants. In cattle, bulk milk tank ELISA and serum pepsinogen assays could be used retrospectively to determine the levels of exposure and hence, in the next season to optimise anthelmintic usage. TST approaches in sheep and goats examined production efficiency and liveweight gain as indicators for treatment and confirmed the value of this approach in maintaining performance and anthelmintic susceptibility in the predominant gastrointestinal nematodes. There is good evidence that the TST approach selected less heavily for the development of resistance in comparison to routine monthly treatments. Further research is required to optimise markers for TT and TST but it is also crucial to encourage producers/advisors to adapt these refugia-based strategies to maintain drug susceptible parasites in order to provide sustainable control.

Direct and indirect effects of bioactive tannin-rich tropical and temperate legumes against nematode infections

Parasitic infections with gastrointestinal nematodes (GINs) represent a major pathological threat associated with the outdoor production of various livestock species. Up to now, the control of these parasitic diseases essentially relied on the use of commercial anthelmintic drugs. However, resistance to anthelmintics is nowadays widespread in worm populations. Recent results indicate that bioactive tanniniferous plants represent a valuable option as an alternative to commercial drugs for the control of GINs. The pertinent use of tannin-containing fodders as nutraceuticals supposes a clear understanding of the mode of action against the worms. The objectives of this paper are: (1) to discuss the nature and quantity of the active molecules involved in the anthelmintic activity; and (2) to review and analyze the changes provoked to the various parasitic stages. The possible involvement of some main polyphenols to explain the bioactivity of some tannin-rich plants will be discussed as well as the possible effects on the various nematode stages, relying on data obtained either with the temperate forage, sainfoin (Onobrychis viciifoliae) or with the tropical legume tree (Lysiloma latisiliquum). The information on the mode of action will be related to the potential consequences for better field applications under entirely different environmental and ecological conditions of productions.

Effects of maternal protein nutrition and subsequent grazing on chicory (Cichorium intybus) on parasitism and performance of lambs

Forty-eight 4- to 5-yr-old Blackface x Bluefaced Leicester (Mule) ewes and their 24-d-old twin lambs were used to assess the effects of maternal protein nutrition and subsequent grazing on chicory (Cichorium intybus) on performance and parasitism. The experiment consisted of 2 grazing periods: safe pasture period and experimental pasture period. During an adaptation period of 66 d, ewes were infected through oral dosing with Teladorsagia circumcincta infective larvae (3 d per wk) and were supplemented with protein (HP) or not (LP) for the last 45 d of this period. At the end of this period, ewes and their lambs were turned out onto a parasitologically safe pasture; all ewes continued to be dosed with parasite (once a week), and HP ewes received protein supplementation for the first 35 d. Ewes and lambs grazed the safe pasture for an additional 43 d after termination of protein supplementation and of oral dosing with parasites. Ewes and their lambs were then moved onto newly established experimental pastures sown with chicory or grass/clover (Lolium perenne/Trifolium repens). During the safe pasture period, HP ewes had decreased fecal egg counts (FEC) compared with LP ewes, whereas HP lambs had temporarily less (P < 0.05) FEC, decreased (P < 0.001) plasma pepsinogen concentrations, and grew faster (P = 0.028) than LP lambs. Lambs grazing chicory had consistently less (P < 0.001) FEC and grew faster (P = 0.013) than lambs grazing grass/clover but had greater (P < 0.001) concentrations of pepsinogen. Pasture larvae counts were decreased (P = 0.07) for the chicory compared with the grass/clover plots. There were no interactions (P > 0.10) between maternal nutrition and grazed forage type on performance or parasitological measurements. Our results suggest that increased maternal protein nutrition and subsequent grazing of chicory independently improve lamb performance and reduce lamb parasitism.

Anthelmintic efficacy and management practices in sheep farms from the state of Rio de Janeiro, Brazil

Anthelmintic resistance in parasites maybe a consequence of over-exposing populations of parasites to drugs or from the commerce/transit of animals harboring resistant parasites. Knowledge of the sensitivity of nematodes to anthelmintics is essential to establish an efficient integrated program of parasite control. In Brazil, producers rely on technology transfer from field professionals and non-technical labor for new management strategies of parasite control. The aim of this work was to determine the practices farmers used for anthelmintic management and to monitor drug efficacy on sheep farms from northern and northwestern regions of the state of Rio de Janeiro, Brazil. A questionnaire was sent to 34 farms, and anthelmintics were tested on ten of these farms. Sheep (n=10/group) were weighed and treated with albendazole, closantel, doramectin, fenbendazole, ivermectin, levamisole, moxidectin, or nitroxynil with their recommended doses. Faeces were collected on the day of treatment and after 7-10 days. The faecal egg count reduction test was evaluated based on RESO 2.0. Among the farmers interviewed, 97% applied commercial anthelmintics to control parasites, 77% rotated anthelmintics annually, 72% used ivermectin as the principal anthelmintic, and 38% applied anthelmintics with a frequency of 30-60 days. On two farms, none of the anthelmintics was efficacious. Levamisole had the best overall efficacy (70%). Albendazole, ivermectin, and fenbendazole were efficacious (above 95%) on only two farms. The present work illustrates the alarming lack of efficacy of drugs even in an area new to sheep farming. It is important to establish alternative strategies of management in a broad program of parasite control for reducing the selection pressure on parasites by the commercially available anthelmintics.

Mapping QTL influencing gastrointestinal nematode burden in Dutch Holstein-Friesian dairy cattle

Background

Parasitic gastroenteritis caused by nematodes is only second to mastitis in terms of health costs to dairy farmers in developed countries. Sustainable control strategies complementing anthelmintics are desired, including selective breeding for enhanced resistance.

Results and Conclusion

To quantify and characterize the genetic contribution to variation in resistance to gastro-intestinal parasites, we measured the heritability of faecal egg and larval counts in the Dutch Holstein-Friesian dairy cattle population. The heritability of faecal egg counts ranged from 7 to 21% and was generally higher than for larval counts. We performed a whole genome scan in 12 paternal half-daughter groups for a total of 768 cows, corresponding to the ~10% most and least infected daughters within each family (selective genotyping). Two genome-wide significant QTL were identified in an across-family analysis, respectively on chromosomes 9 and 19, coinciding with previous findings in orthologous chromosomal regions in sheep. We identified six more suggestive QTL by within-family analysis. An additional 73 informative SNPs were genotyped on chromosome 19 and the ensuing high density map used in a variance component approach to simultaneously exploit linkage and linkage disequilibrium in an initial inconclusive attempt to refine the QTL map position.

Anthelmintic efficacy and dose determination of Albizia anthelmintica against gastrointestinal nematodes in naturally infected Ugandan sheep

Weight loss, stunted growth, and death caused by gastrointestinal parasites are major constraints to livestock productivity, especially in tropical and developing countries where regular use, and misuse, of anthelmintics has led to nematode resistance. Albizia anthelmintica Brong. (Fabaceae) is traditionally employed throughout East Africa to treat helminth parasitosis in livestock. Reported efficacy has varied from 90% against mixed nematodes to just 19% against Haemonchus contortus alone. The objective of this study was to assess the anthelmintic effect of A. anthelmintica against naturally occurring infections of mixed gastrointestinal parasites, and to establish an effective treatment dose, in sheep under pastoral field conditions of northern Uganda. A. anthelmintica bark was collected and prepared according to local custom and packed into gel capsules. Fifty-five young female local mixed-breed lambs were randomly assigned to six groups, including a positive control group that received levamisole (synthetic anthelmintic) and a negative control group that received no treatment. Following the World Association for the Advancement of Veterinary Parasitology (WAAVP) dose determination guidelines, the other four groups were treated with varying doses of A. anthelmintica. Statistical analyses (using generalized linear models) were performed to assess treatment effect. There was a significant treatment (group) effect on parasite egg/oocyte counts per gram (EPG) for nematodes, but not for coccidia. The most effective dose against nematodes (0.8g, 58.7mg/kg) closely approximates what is usually given by traditional healers, 0.9g/adult sheep. It provided major and significant reduction in EPG as compared to the negative control. Anthelmintic efficacy was estimated using percent faecal egg count reduction (FECR). Other than the positive control, animals in the standard dose group showed the greatest decline in shedding of nematode eggs, with an FECR of 78%. This study indicates that A. anthelmintica holds potential as part of an integrated management plan for the control of helminths in developing countries.

Effect of the consumption of Lysiloma latisiliquum on the larval establishment of gastrointestinal nematodes in goats

The consumption of tannin-rich (TR) forages has been associated with negative effects against gastrointestinal nematodes and with an improved host resilience. It has been hypothesized that tannins affect the capacity of infective larvae to establish in the mucosae of the host. In this study, we aimed at testing this hypothesis using Lysiloma latisiliquum, a tropical TR tree. The objectives were: (i) to evaluate the effect of the consumption of L. latisiliquum on the establishment of nematode third-stage larvae (L3) in goats; (ii) to define the role of tannins in these effects in vivo by using an inhibitor (polyethylene glycol, PEG); and (iii) to examine a possible indirect effect of tannins on the inflammatory response in the digestive mucosa. Eighteen Criollo goats composed three experimental groups. The control group received fresh leaves of Brosimum alicastrum, a plant with a low level of tannins. Two groups received L. latisiliquum leaves either with (L.L.+PEG) or without (L.L.) daily addition of 25 g PEG. After a 7-day adaptation period, each goat was infected with both Haemonchus contortus and Trichostrongylus colubriformis (3000 L3 per species). The goats were slaughtered 5 days after infection and worm counts and histological analyses were performed. No difference in the voluntary feed intake of foliage was observed between the 3 groups. The consumption of L. latisiliquum significantly reduced the larval establishment of both nematode species compared to the control (P<0.01). For both worm species, the effects were totally alleviated with PEG (L.L.+PEG group), suggesting a major role of tannins in the observed effects. Only minor differences in the mucosal cellular response were observed between the 3 groups. These results confirm that the consumption of TR plants reduces the establishment of nematode larvae in the host and that a direct effect is principally involved.

The role of biotic factors in the transmission of free-living endohelminth stages

The transmission success of free-living larval stages of endohelminths is generally modulated by a variety of abiotic and biotic environmental factors. Whereas the role of abiotic factors (including anthropogenic pollutants) has been in focus in numerous studies and summarized in reviews, the role of biotic factors has received much less attention. Here, we review the existing body of literature from the fields of parasitology and ecology and recognize 6 different types of biotic factors with the potential to alter larval transmission processes. We found that experimental studies generally indicate strong effects of biotic factors, and the latter emerge as potentially important, underestimated determinants in the transmission ecology of free-living endohelminth stages. This implies that biodiversity, in general, should have significant effects on parasite transmission and population dynamics. These effects are likely to interact with natural abiotic factors and anthropogenic pollutants. Investigating the interplay of abiotic and biotic factors will not only be crucial for a thorough understanding of parasite transmission processes, but will also be a prerequisite to anticipate the effects of climate and other global changes on helminth parasites and their host communities.

In vitro nematicidal effects of medicinal plants from the Sierra de Huautla, Biosphere Reserve, Morelos, Mexico against Haemonchus contortus infective larvae

Twenty extracts from plants from Sierra de Huautla Biosphere Reserve, Morelos, Mexico were evaluated against Haemonchus contortus infective larvae in an in vitro assay. The plant species evaluated were Bursera copallifera, B. grandifolia, Lippia graveolens, Passiflora mexicana, Prosopis laevigata, Randia echinocarpa and Urtica dioica. The plants were separated into their parts and macerated with different solvents (n-hexane, acetone, ethanol and methanol). An in vitro assay was used to evaluate the anthelmintic activity against unsheathed third stage H. contortus infective larvae. The experiment was carried out in 24-well cell culture plates at room temperature with three replicates per treatment and using a concentration of 20 mg ml- 1. Ten 5 microl aliquots were taken from the corresponding wells and deposited on a slide for microscopical observation at 24, 48, 72 and 96 h post-exposure. The evaluation criteria were based on the average numbers of live and/or dead larvae in the different treatments. Alive and dead larval numbers were statistically analysed through the ANOVA test (P>0.01). The Tukey test was used as a complementary tool to determine which treatment was different from the other treatments (P>0.05). The highest mortality was observed with P. laevigata hexanic extract from stem and leaves combined, which produced 51%, 81% and 86% larval mortality at 24, 48 and 72 h post-exposure, respectively. On the other hand, B. copallifera stem acetonic extract exhibited 18%, 59% and 66% nematicidal activity after 24, 48 and 72 h of exposure, respectively.

Combining the effects of supplementary feeding and copper oxide needles for the control of gastrointestinal nematodes in browsing goats

The aim was to assess the benefits obtained from combining supplementary feeding and copper needles (COWP), compared to the use of both approaches independently, for the control of gastrointestinal nematode (GIN) infections in browsing kids. Forty-four nematode free Criollo kids were exposed to natural parasite infection. The kids were divided into six experimental groups: not treated, supplemented (NT-S), not treated, not supplemented (NT-NS), moxidectin treated, supplemented (M-S), moxidectin treated not supplemented (M-NS), copper treated, supplemented (COWP-S) and copper treated, non-supplemented (COWP-NS). Copper treated groups received Copinox (2 g capsules) on day 0 and on day 60 of the trial. Moxidectin treated groups received Cydectin (0.2 mg/kg of body weight s.c.) every 28 days. Three of the groups received individual supplementation (100 g of feed/day fresh basis; 74% sorghum: 26% soybean meal; NT-S, M-S and COWP-S) and the other three groups were not supplemented (NT-NS, M-NS and COWP-NS). Animals browsed native vegetation (6.5 h/day) during the wet season (154 days). Kids were weighed every 14 days to determine live weight gain (LWG) and blood and faecal samples were obtained to determine packed cell volume (PCV), haemoglobin (Hb), peripheral eosinophil counts (PEC) and faecal egg counts (FEC). At the end of the trial, four kids of each group were euthanatized (six kids in each COWP treated group). Worm burdens, female worm lengths and prolificacy were determined. Liver samples were used to determine copper concentration and were stained with haematoxylin-eosin to determine microscopic lesions. Animals receiving the combination of supplementary feeding and COWP improved their LWG, PCV and Hb to similar levels of animals with suppressive AH treatment. This was not the case when COWP was used without supplementation. Liver copper concentration in COWP treated groups increased significantly especially in the COWP-NS kids but this was not associated with liver lesions or clinical signs. Post-mortem Haemonchus contortus and Trichostrongylus colubriformis worm counts had a tendency to be reduced in the different groups (66-35% reduction) compared to NT-NS group at the end of the trial (P>0.05). Also, COWP treatment and/or supplementation reduced female worm length of T. colubriformis and prolificacy of H. contortus and T. colubriformis. This study, confirmed the value of nutritional supplementation in the control of GIN in growing kids. The use of COWP in addition to supplementation had a limited contribution on the kids' resilience against GIN. This may be due to the reduced infection of H. contortus during this trial.