Benzimidazole and Aminoalcohol Derivatives Show in Vitro Anthelmintic Activity Against Trichuris Muris and Heligmosomoides Polygyrus

Background: Infections by gastrointestinal nematodes cause significant economic losses and disease in both human and animals worldwide. The discovery of novel anthelmintic drugs is a crucial point in maintaining control of these parasitic infections.Methods: For this purpose, the aim of the present study was to evaluate the potential anthelmintic activity of three series of compounds against the gastrointestinal nematodes Trichuris muris and Heligmosomoides polygyrusin vitro. The compounds tested are derivatives of benzimidazole, lipidic aminoalcohols and diamines. A primary screening was performed to select those compounds with an ability to inhibit T. muris L1 motility by more than 90% at a single concentration of 100 µM, and then, their respective IC50s were calculated. Those compounds with IC50 lower than 10 µM were also tested against the adult stage of T. muris and H. polygyrus at a single concentration of 10µM.Results: Of the 41 initial compounds screened, only compounds AO14, BZ6 and BZ12 had IC50s lower than 10 µM on T. muris L1 assay, showing IC50 values of 3.30, 8.89 and 4.17 µM, respectively. However, only two of them displayed activity against the adult stage of the parasites: BZ12 killed 81% of adults of T. muris (IC50 of 8.1 µM) and 53% of H. polygyrus while BZ6 killed 100% of H. polygyrus adults (IC50 of 5.3 µM) but only 17% of T. muris. Conclusions: BZ6 and BZ12 could be considered as potential candidates for further in vivo efficacy testing.

Effect of Adhatoda vasica (Acanthaceae) on Antioxidant and Immunological Profile in Sheep

Background: A study was conducted to evaluate the antioxidant and immunological profile of methanolic extract of Adhatoda vasica leaves (AVE) in naturally infected sheep with gastrointestinal nematodes and compared with commonly used anthelmintic albendazole in sheep. Methods: Fifty four sheep found positive for gastrointestinal nematodes were divided into 3 equal groups, GI (infected-untreated: control), GII (infected- AVE treated) and GIII (infected- albendazole treated). Blood samples were drawn on 5th and 14th day after treatment for analysis of oxidative stress markers such as TBARS, TAC, SOD and catalase and immunological parameters such as total immunoglobulin, IgG and IL-10. Result: Helminthiasis in sheep cause a considerable oxidative stress. The anthelmintic activity of Adhatoda vasica surpassed the conventional synthetic drug albendazole in sheep in terms of oxidative and immunological changes in blood.

Anthelmintic Drugs Resistance of Gastrointestinal Nematodes of Naturally Infected Goats in Haramaya, Ethiopia

Gastrointestinal parasites and their anthelmintic resistance are major constraints to goat production in Ethiopia. Experimental investigation by faecal egg count reduction test (FECRT) and larval cultures were used to assess the occurrence of anthelmintic resistance in naturally infected goats with gastrointestinal nematodes (GIN) in Haramaya, Ethiopia. One hundred goats with a minimum of 150 eggs per gram (EPG) count were selected and randomly divided into five groups; 20 goats in each group; four treated and one untreated group. The result of the faecal egg count reduction test percentage (FECRT%) and the lower 95% confidence limit showed the presence of anthelmintic resistance for all tested drugs except tetramisole. FECRT% and lower 95% confidence limit were 69.9% and 36.9 for albendazole, 84.3% and 66.1 for tetraclozan, 95.7% and 87.4 for tetramisole and 71.1% and 38.2 for ivermectin respectively. Trichostrongylus, Teladorsagia and Haemonchus showed anthelmintic resistance for tested drugs. Coproculture from different treatment group revealed Trichostrongylus (69.2% in ivermectin and 59.6% in albendazole) were the predominant nematode followed by Teladorsagia (21.9% in albendazole and 14.7% in ivermectin). In tetraclozan treatment group, Trichostrongylus (42%) and Teladorsagia (41.3%) were comparable, followed by Haemonchus (13%). In group treated with tetramisole, Teladorsagia (54.3%) were the most frequently detected nematode followed by Trichostrongylus (25.7%) and Haemonchus (11.4%). Therefore, this study demonstrated the presence of multi-drug resistant nematodes that may limit the productivity of goats. Moreover, further studies covering wider areas of Ethiopia and mechanisms of nematode resistance need to be studied in future.

Ethnoveterinary survey of plants used for the control of gastrointestinal nematodes in sheep at three agro-ecological zones in the Eastern Cape Province of South Africa

Background: With exception of the desert biome, all of South Africa’s biomes occur in the Eastern Cape. The province is known to have high numbers of livestock that are mostly found in communal farming areas. Multi-drug resistance of gastrointestinal nematodes against major classes of conventional anthelmintics and the high cost of synthetic drugs calls for an urgent search for different control strategies of nematodes.Aim: A survey was conducted to identify and document plant species used to control gastrointestinal nematodes of livestock in Ciko, Goso and Upper Ngqumeya communities in the Eastern Cape Province.Setting: The study included filed observations and transect walks, as well as a standardized questionnaire given to 48 sheep farmers.Methodology: Forty-eight livestock farmers including men and women of mixed ages were interviewed. The information was obtained through the use of a structured questionnaire, field observations and transect walks. Data generated were analysed using descriptive statistics with frequency of citation (FC) and relative frequency of citation (RFC) as quantitative.Results: A total of 11 plant species from different genera were reportedly available and used to control gastrointestinal nematodes. Aloe ferox (0.67) and Zanthoxylum capense (0.44) had the highest values of RFC followed by Strychnos henningsii (0.23) and Elaphantorhhiza elephantine (0.21) and were widely known by the people of the study areas. The three most frequently used plant parts were leaves, roots and bark accounting for about 36.4%, 27.3% and 27.3%, respectively. The ethnoveterinary medicines were prepared in the form of decoctions and infusions. Oral administration of the concoctions was the only route of administration. The major constraints of sheep production as perceived by the farmers were prevalence of internal (36%) and external parasites (18.1%). All medicinal plants used were native and collected from the wild. The most dominant life forms were trees (45.4%), followed by herbs (36.4%) and shrubs (18.2%). Homestead expansion was ranked as the major threat (26%) to medicinal plants followed by firewood (21%). In-situ (protection through rangers) was the most frequently mentioned (67%) conservation practice used by farmers to protect the loss of medicinal plants followed by ex-situ (33%).Conclusion: In the light of data gathered on the surveyed plants, it appeared the plants play a role in the healthcare of sheep in rural communities. Further studies are required to analyse the plants for their chemical composition and biological properties.

Gastrointestinal nematodes and Fasciola hepatica in Norwegian cattle herds: a questionnaire to investigate farmers’ perceptions and control strategies

Background Pasture management influences the prevalence and impact of the pasture parasites (PP) in cattle herds, which cause production-limiting disease worldwide. Evaluating farmer management strategies is vital when considering sustainable PP control practices. The aim of this questionnaire-based study was to describe the pasture management and control strategies regarding PP in Norwegian beef cattle (BC) and dairy cattle (DC) production systems with a focus on gastrointestinal nematodes (GIN) and Fasciola hepatica. Results A total of 745 responses from BC (return rate 20.5%) and 1347 responses from DC farmers (30.7%) were included. The mean total pasture time for DC was 4.2 months for first-season grazers and 4.3 months for second-season grazers and cows, while the corresponding finding in BC was 5.4 months. Home pasture was used for most of the pasture period, particularly for first-season grazer dairy heifers (81%), which were also commonly grazed on the same pasture every year (79%). For most farmers it was necessary for grazing areas to be used for cattle for more than one season (77% of BC farmers and 89% of DC farmers). However, changing the pasture during the season was common in both DC (67%) and BC (70%) herds. The majority of DC farmers (60%) stated that they did not consider that they had a problem with PP. Of the remaining 40%, few respondents could specify whether their herds had a problem due to infection by GIN (11%) or liver flukes (12%). Treatment for GIN was performed by 52% of DC and 34% of BC farmers. Diagnostic faecal samples were collected upon suspicion of parasitic disease by 5% of DC and 16% of BC farmers. Veterinarians were stated as a central source of information about parasite management and treatment. Conclusions Potential risks for exposure to PP were identified, such as use of the same pasture every year for first-season grazers and frequent use of home pasture. The perception of problems related to PP appeared low. Regular anthelmintic treatment without concurrent use of diagnostic faecal samples seems to be common practice.

Disclosing the bioactive metabolites involved in the in vitro anthelmintic effects of salt-tolerant plants through a combined approach using PVPP and HPLC-ESI-MSn

Strategies to reduce dependence on synthetic drugs for the treatment of gastrointestinal nematodes (GIN) infections in ruminants include the search for novel anthelmintic scaffolds on plants, yet salt-tolerant plants remain overlooked. This study aims to evaluate the in vitro anthelmintic properties of selected salt-tolerant plants against GIN, and identify the potential bioactive secondary metabolites involved. For that purpose, 80% acetone/water extracts were prepared from dried biomass of aerial organs of nine salt-tolerant plant species and tested against Haemonchus contortus and Trichostrongylus colubriformis by the Larval Exsheathment Inhibition Assay (LEIA) and Egg Hatching Inhibition Assay (EHIA). Pistacia lentiscus, Limoniatrum monopetalum, Cladium mariscus and Helychrisum italicum picardi were the most active in both GIN and life stages. To investigate the role of polyphenols in the anthelmintic activity, four selected extracts were treated with polyvinylpolypyrrolidone (PVPP), and non-treated and treated samples were further characterized by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn). While polyphenols seem responsible for the EHIA properties, they are partially accountable to LEIA results. Several phenolics involved in the anthelmintic effects were identified and discussed. In sum, these species are rich sources of anthelmintic compounds and, therefore, are of major interest for nutraceutical and/or phytotherapeutic applications against GIN in ruminants.

Metabarcoding in two isolated populations of wild roe deer (Capreolus capreolus) reveals variation in gastrointestinal nematode community composition between regions and among age classes

Background Gastrointestinal nematodes are ubiquitous for both domestic and wild ungulates and have varying consequences for health and fitness. They exist as complex communities of multiple co-infecting species, and we have a limited understanding of how these communities vary in different hosts, regions and circumstances or of how this affects their impacts. Methods We have undertaken ITS2 rDNA nemabiome metabarcoding with next-generation sequencing on populations of nematode larvae isolated from 149 fecal samples of roe deer of different sex and age classes in the two isolated populations of Chizé and Trois Fontaines in France not co-grazing with any domestic ungulate species. Results We identified 100 amplified sequence variants (ASVs) that were assigned to 14 gastrointestinal nematode taxa overall at either genus (29%) or species (71%) level. These taxa were dominated by parasites classically found in cervids—e.g. Ostertagia leptospicularis, Spiculopteragia spp. Higher parasite species diversity was present in the Trois Fontaines population than in the Chizé population including the presence of species more typically seen in domestic livestock (Haemonchus contortus, Bunostomum sp., Cooperia punctata, Teladorsagia circumcincta). No differences in parasite species diversity or community composition were seen in the samples collected from three zones of differing habitat quality within the Chizé study area. Young roe deer hosted the highest diversity of gastrointestinal nematodes, with more pronounced effects of age apparent in Trois Fontaines. The effect of host age differed between gastrointestinal nematode species, e.g. there was little effect on O. leptospicularis but a large effect on Trichostrongylus spp. No effect of host sex was detected in either site. Conclusions The presence of some livestock parasite species in the Trois Fontaines roe deer population was unexpected given the isolation of this population away from grazing domestic livestock since decades. Overall, our results illustrate the influence of host traits and the local environment on roe deer nemabiome and demonstrate the power of the nemabiome metabarcoding approach to elucidate the composition of gastrointestinal nematode communities in wildlife. Graphical Abstract

Seasonal epidemiology of gastrointestinal nematodes of cattle in the northern continental climate zone of western Canada as revealed by internal transcribed spacer-2 ribosomal DNA nemabiome barcoding

Background Gastrointestinal nematode (GIN) epidemiology is changing in many regions of the world due to factors such as global warming and emerging anthelmintic resistance. However, the dynamics of these changes in northern continental climate zones are poorly understood due to a lack of empirical data. Methods We studied the accumulation on pasture of free-living infective third-stage larvae (L3) of different GIN species from fecal pats deposited by naturally infected grazing cattle. The field study was conducted on three organic farms in Alberta, western Canada. Grass samples adjacent to 24 fecal pats were collected from each of three different pastures on each farm. Internal transcribed spacer-2 nemabiome metabarcoding was used to determine the GIN species composition of the harvested larvae. The rotational grazing patterns of the cattle ensured that each pasture was contaminated only once by fecal pat deposition. This design allowed us to monitor the accumulation of L3 of specific GIN species on pastures under natural climatic conditions without the confounding effects of pasture recontamination or anthelmintic treatments. Results In seven out of the nine pastures, grass L3 counts peaked approximately 9 weeks after fecal deposition and then gradually declined. However, a relatively large number of L3 remained in the fecal pats at the end of the grazing season. Nemabiome metabarcoding revealed that Cooperia oncophora and Ostertagia ostertagi were the two most abundant species on all of the pastures and that the dynamics of larval accumulation on grass were similar for both species. Daily precipitation and temperature across the whole sampling period were similar for most of the pastures, and multiple linear regression showed that accumulated rainfall 1 week prior to sample collection had a significant impact on the pasture L3 population, but accumulated rainfall 3 weeks prior to sample collection did not. Conclusions The results suggest that the pasture L3 population was altered by short-term microclimatic conditions conducive for horizontal migration onto grass. Overall, the results show the importance of the fecal pat as a refuge and reservoir for L3 of cattle GIN on western Canadian pastures, and provide an evidence base for the risk assessment of rotational grazing management in the region. Graphical Abstract