Development Of Anthelmintic Resistance Research Articles

Epidemiology and field efficacy of anthelmintic drugs associated with gastrointestinal nematodes of sheep in Nejo district, Oromia, Ethiopia

Gastrointestinal nematodes (GINs) are major constraints to health and productivity of small ruminants. Methods of their control relies mainly on anthelmintic drugs; however, the indiscriminate use of these drugs could lead to the development of anthelmintic resistance (AR). This study aimed to investigate the epidemiology of GINs infection, and field evaluation of anthelmintic efficacy in sheep. The epidemiological data were collected using a cross-sectional study design while a farm-based field study design was employed for the evaluation of anthelminthic efficacy. Furthermore, standard parasitological techniques were employed for qualitative and quantitative worm identification. The overall prevalence indicated 50.3%. Six genera of GINs (Haemonchus, Trichostrongylus, Oesophagostomum/Chabertia, Trichuris, Teladosargia/Ostertagia and Nematodirus) were identified. Among the identified genera, Haemonchus (25.4%) and Trichostrongylus (24.8%) were the dominant genera followed by mixed infection (21.8%), Oesophagostomum/Chabertia (10.4%), Trichuris (7.8%), Teladosargia (Ostertagia) (5.7%) and Nematodirus (4.1%). Mixed infections consisted either of double infections with Haemonchus and Trichostrongylus, or triple infections with Haemonchus, Trichostrongylus and Trichuris. The McMaster egg counting results showed that the mean EPG of infected sheep was 845.6. The results also showed 66 (34.2%), 101 (52.3%) and 26 (13.5%) sheep had low, moderate and heavy worm burden, respectively. Albendazole and Ivermectin showed low efficacy (percentage reductions = 90% and 92%; 95% lower confidence limit = 82.1% and 83.6% respectively) whereas Tetramisole was effective (FECR% = 96.8%; 95% LCL = 93.4%). Factors such as age, body condition, management system and past deworming history of sheep were found to have a statistically significant (p < 0.05) influence on the occurrence and burden of the worms. This is further explained as the highest prevalence and worm burden was detected in sheep of young age (p = 0.008; OR = 0.58; 95% CI = 0.39–0.87), poor body condition (p = 0.001; OR = 0.08; 95% CI = 0.04–0.16) and sheep kept under semi-intensive (p = 0.04; OR = 1.53; 95% CI = 1.02–2.29) with no deworming history for the last two months (p = 0.001; OR = 2.97; 95% CI = 1.94–4.56). The study results revealed that nematode infections were among sheep health constraints that could hurt their productivity while low efficacy of Albendazole and Ivermectin were detected. Therefore, the appropriate management techniques of GIN infections should be designed and implemented. Moreover, a further study involving more sensitive techniques (e.g. Mini-FLOTAC, molecular, and serological techniques) should be conducted by considering different host and environmental risk factors such as production level and seasons.

Anthelmintic resistance in soil-transmitted helminths: One-Health considerations

The One-Health approach recognizes the intricate connection between human, animal, and environmental health, and that cooperative effort from various professionals provides comprehensive awareness and potential solutions for issues relating to the health of people, animals, and the environment. This approach has increasingly gained appeal as the standard strategy for tackling emerging infectious diseases, most of which are zoonoses. Treatment with anthelmintics (AHs) without a doubt minimizes the severe consequences of soil-transmitted helminths (STHs); however, evidence of anthelmintic resistance (AR) development to different helminths of practically every animal species and the distinct groups of AHs is overwhelming globally. In this regard, the correlation between the application of anthelmintic drugs in both human and animal populations and the consequent development of anthelmintic resistance in STHs within the context of a One-Health framework is explored. This review provides an overview of the major human and animal STHs, treatment of the STHs, AR development and drug-related factors contributing towards AR, One-Health and STHs, and an outline of some One-Health strategies that may be used in combating AR.

Gastrointestinal parasitosis in cattle: Unveiling the landscape across diverse production systems in Bangladesh.

Factors influencing parasitosis in cattle in Bangladesh remain inadequately explored, necessitating a comprehensive investigation for interventions and sustainable livestock farming. We conducted this study to estimate the prevalence and distribution of gastrointestinal parasites, exploring their intricate relationship with farm management practices across a spectrum of small-, medium-, and large-scale commercial farms. We conducted this study in the Chattogram district of Bangladesh. We collected a total of 189 freshly voided faecal samples from different farms. We recorded the age, breed, milking status, sex, body condition score, and anthelmintic use history of the sampled animals. We processed the samples using the direct smear method, with the identification of one egg per sample being considered positive. We estimated the prevalence of gastrointestinal parasite infection in large-scale (52.1%), medium-scale (54.5%), and small-scale farms (70.0%), with statistically significant differences (p ≤ 0.05). Both pregnant and lactating cows, as well as indigenous cattle, were more likely to have gastrointestinal parasites (p ≤ 0.05). The predominant parasites across farms of all sizes were trematodes (Paramphistomum spp. and Schistosomas spp.) and protozoa (Balantidium coli and Coccidia spp.). Poor farm management practices, such as no pasture management and inadequate deworming regimens, may contribute to the elevated prevalence and infection load observed on small-scale farms. The increased parasitosis in previously dewormed animals can be attributed to the development of anthelmintic resistance against gastrointestinal parasites. Implementing proper and effective deworming strategies is crucial to preventing gastrointestinal parasitosis and mitigating the risk of anthelmintic resistance.

Seasonal Prevalence and Status of Anthelmintic Resistance of Goats' Gastrointestinal Nematodes, Mirab Abaya, Southern Ethiopia.

Goats are an important source of livelihood especially for smallholder communities. But gastrointestinal nematodosis is the greatest threats of goat production. A repeated cross-sectional and field experimental study design was conducted from December 2020 to August 2021 in Mirab Abaya district, with the aim of seasonal prevalence gastrointestinal nematode infection and assessment of anthelmintic resistance. A systematic random sampling strategy was used to select the study goats. The overall prevalence of gastrointestinal nematode infections of goats in the study area was 57.9% (95% CI: 54.4-61.4), of which 48.7% (95% CI: 43.7-53.7) and 67.2% (95% CI: 62.3-71.7) accounted to dry and wet seasons, respectively. The multivariable logistic regression analysis showed that season, age, sex, and flock size were significantly (p < 0.05) influenced the prevalence of gastrointestinal nematode infection of goats. The number of eggs per gram of faeces (EPG) was ranged from 100 to 2500. The overall mean egg per gram of faeces (EPG) was 461.1 ± 20.9. The mean EPG of wet season (532.7 ± 28.6) was higher than the dry season (362.3 ± 29.1). From faecal culture, 552 nematode larvae were recovered, and the most commonly identified nematode genera were Haemonchus (36.4%) that followed by Trichostrongylus (28.1%), Oesophagostomum (15.4%), Bunostomum (11.4), Teladorsagia (5.4%), and Strongyloides (3.0%) species. From the anthelmintic resistance test in the field, the percentage reduction and 95% confidence limit of albendazole were 96% (84.2-99.0) and 97.0% (84.6-99.4) in dry and wet seasons, respectively. Here, the lower limit of 95% CI was less than 90% both in dry and wet seasons; and hence, albendazole was suspected for resistance development by gastrointestinal nematode. From a pooled faecal culture that collected from albendazole-treated goats, Haemonchus species was recovered. Therefore, due attention shall be by animal health professionals in the area in the use of albendazole. Animal health extension work to create awareness of how anthelmintic is used is helpful in reducing the risk. Changing the type of anthelmintic drug after using for some period will minimize the risk of anthelmintic resistance development.

Supplementation of minerals and vitamins influences optimal targeted selective treatment thresholds for the control of gastro-intestinal nematodes in lambs

Targeted Selective Treatment (TST) is a gastrointestinal nematode (GIN) control strategy where anthelmintic treatment decisions are made at an individual animal level. TST has been proven to reduce anthelmintic use and subsequently slow down anthelmintic resistance development, however questions remain regarding optimal TST methods and their applicability across farms.In this study, the influence of Mineral and Vitamin (MV) supplementation on optimal energy utilisation (EU) TST thresholds was assessed on three Welsh farms. In total, 360 lambs were split into two groups, MV supplemented and control, and were treated with an anthelmintic against GIN at the midway point of the experiment. Lambs that improved their EU efficiency post treatment were deemed to have benefited from anthelmintic treatment. Optimal EU TST thresholds was determined for each treatment group per farm using Youden’s J statistic where the treatment threshold retrospectively exhibiting the greatest combined sensitivity and specificity in correctly identifying lambs benefiting from treatment was deemed to be optimal.Results demonstrated that the optimal EU TST threshold was higher in MV supplemented groups at 0.72, 0.71 and 0.56 versus 0.58, 0.67, 0.51 for control groups on each respective farm. Identification of lambs for TST was more effective when using an optimised EU TST threshold, compared to when using the standard EU TST threshold of 0.66.The study highlights that applying standard EU TST thresholds may not be appropriate on all commercial farms with factors including MV status as noted in this study likely to influence optimal EU TST thresholds. Additional refinement of TST systems can further strengthen their applicability across sheep flocks.

Anthelmintic effects of aqueous extract &lt;i&gt;Balanites aegyptiaca&lt;/i&gt; stem bark on strongyle larvae and the earthworm &lt;i&gt;Pheretima posthuma&lt;/i&gt;

The development of anthelmintic resistance and the high cost of conventional anthelmintics have led to the evaluation of medicinal plants as an alternative source of anthelmintics. In the current study, in vitro experiments were conducted to determine the possible anthelmintic effects of Balanites aegyptiaca stem bark aqueous extract on Strongyle larvae and the earthworm Pheretima posthuma. The in vitro studies revealed that the extract at graded concentrations of 300 mg/ml, 400 mg/ml, 500 mg/ml and 600 mg/ml exhibited larvicidal activity (p&lt;0.05) against earthworms with 600 mg/ml having the highest activity causing paralysis and death. In a similar vein, a graded concentration response was observed against Strongyle larvae. The highest effective concentration on larvae was 250 mg/ml which had a larval mortality rate of 100% and a mortality index of one (1) comparable with that of albendazole. The IC50 and IC99 values for the time of paralysis were 442.7mg/ml and 767.80mg/ml respectively. The anthelmintic activity exhibited by the extract could be linked to the presence of phytochemicals present in the plant. These findings support the folkloric use of this plant in the control and management of gastrointestinal nematodes in humans and animals.

Selective Anthelmintic Treatment in Horses in Sweden Based on Coprological Analyses: Ten-Year Results.

In Sweden, routine deworming has been used for several decades; however, to slow down the development of anthelmintic resistance, selective treatment is currently recommended. As part of a monitoring programme, equestrian premises submitted faecal samples to the National Veterinary Institute (SVA) twice per year between 2008 and 2017. Analyses for strongyles (small and large), tapeworms and ascarids, followed by premise-specific advice regarding deworming and parasite control strategies, were provided. In total, 43,330 faecal samples, collected from 26,625 horses on 935 premises in springtime (March to June), were analysed by quantitative or semi-quantitative flotation. Moreover, Strongylus vulgaris was detected by larval culture or PCR. Between 4 and 11% of individual horses tested positive for S. vulgaris and 3-10% were shedding tapeworm eggs. There were recurrent high and low egg shedders; 75% of horses with S. vulgaris appeared to have been recently introduced into the herd; the proportion of S. vulgaris-positive premises increased when individual samples rather than pooled samples were used. Based on the results of S. vulgaris diagnostics and strongyle egg-shedding level, 59% of the horses did not need to be dewormed.

Retained efficacy of ivermectin against cyathostomins in Swedish horse establishments practicing selective anthelmintic treatment

Cyathostominae are ubiquitous to grazing horses and regarded the most prevalent internal parasite in the horse. Unfortunately, decades of indiscriminate use of anthelmintic drugs have resulted in the development of resistance in cyathostomins to all currently available drug groups, the most recent being a documented lack of efficacy to the macrocyclic lactones (ML). In vivo determination of anthelmintic resistance in horses most often utilises the faecal egg count reduction test (FECRT). Further, a shortened egg reappearance period (ERP) can indicate a change in response to the applied treatment and suggest an upcoming reduction of efficacy. Although both true resistance as demonstrated by the FECRT and shorter ERPs after ML treatment have now been shown in cyathostomins worldwide, the efficacy of ML as regards to cyathostomins in Sweden is currently unknown. The aim of the present study was therefore to determine FECRTs and ERPs after ivermectin (IVM) treatment in Swedish horses. Sixteen equestrian establishments with a minimum of six horses excreting at least 150 eggs per gram faeces (EPG) at screening were selected. For each establishment, FECRTs and ERPs were determined by collecting faecal samples prior to and 14 days after IVM treatment (200 µg/kg), and thereafter at weekly intervals for a total of eight weeks. All participants responded to a questionnaire detailing pasture management methods and anthelmintic routines.Questionnaire results showed that the majority of establishments (69%) only treated horses with anthelmintic drugs if indicated by faecal diagnostics and all of the establishments had a mean FECRT exceeding 99.0% and ERPs ranging from six to over eight weeks. The ERP was shown to increase with age as young individuals were shown to excrete cyathostomin eggs earlier after treatment compared with older horses (R = 0.21, p = 0.015). Riding schools, stud farms and those declaring not to use separate summer and winter paddocks had significantly shorter ERPs (p <0.01).In conclusion, retained ERPs and no confirmed resistance to IVM were found in Swedish equine establishments practising selective anthelmintic treatment, and supports the use of selective deworming regimens as a means of reducing the risk of anthelmintic resistance development.

NOVEL STRATEGIES FOR THE CONTROL OF GASTROINTESTINAL NEMATODES IN SHEEP

Gastrointestinal nematodes are very important parasites of domestic animals, especially in small ruminants. In sheep, diseases usually have a subclinical form with a decrease in body weight and production, and sometimes there can be visible clinical symptoms such as anorexia, anemia, severe diarrhea and protein loss, all of which together can lead to death. Commercial drugs such as benzimidazole and macrocyclic lactones have been successfully used for decades to control these parasites. However, the irrational application of these drugs has led to the development of anthelmintic resistance, a decrease in their effectiveness and consequent economic losses that threaten the sustainability of sheep breeding. In addition, the use of commercial preparations is also associated with the residues in animal products and the environment, and there is also an increase in the price of these preparations. For this reason, novel strategies for controlling of these parasites are actively seeking, with the goal of establishing an integrated approach that involves the application of several different strategies. On the one hand, these include strategies for the rational application of commercial preparations based on refugia (targeted treatments, targeted selective treatments), as well as the combination and rotation of anthelmintics from different chemical groups. On the other hand, an integrated approach implies the use of different alternative strategies such as genetic selection of animals naturally resistant to nematodes, rational management of pastures, balanced nutrition with supplementary nutrients, biological control (use of fungi, bacteria, etc.), development of vaccines as well as the use of botanical preparations (plants and their products such as extracts and essential oils). Various studies have proven the effectiveness of the mentioned strategies in the control of gastrointestinal nematodes of sheep, whereby the best results are achieved by their combined application. Thus, it is possible to slow down the development and spread of anthelmintic resistance, as well as achieve sustainable control of these parasites and reduce economic losses.

Clinico-therapeutic Studies on Haemonchosis in Goats

Background: Haemonchosis is one of the major parasitic infestations in small ruminants. Haemonchus contortus is a highly pathogenic parasite that localises in the abomasum of affected animals and exerts its pathogenicity by blood-sucking activity, adversely affecting the health and productivity of animals. In recent years, there is widespread development of anthelmintic resistance against Haemonchus spp. Therefore, a sustainable strategy needs to be implemented to effectively control haemonchosis in goats. The aim of the present study was to find out the efficacy of herbal anthelmintic drug (Carica papaya aqueous seed extract) and haemato-biochemical alterations in Haemonchus infection. Methods: In this study, goats were screened for Haemonchus spp. by the FAMACHA technique. Hemato-biochemical examination was done before and after the therapeutic trial. Herbal anthelmintic drug was prepared from Papaya seed. In-vitro and in-vivo trial were carried out to test the efficacy of prepared herbal anthelmintic drug. Result: The present study showed that FAMACHA can be used for the early screening of Haemonchus spp. in a herd. Significant improvement in haemato-biochemical examination was found in the group treated with the prepared herbal anthelmintic drug. Thus, the herbal anthelmintic (Carica papaya seed extract) can be a good alternative for controlling Haemonchosis in goats.

103 Impact of Fescue Variety on Fecal Egg Counts in Mature Beef Cattle

Abstract Fescue toxicosis decreases beef cattle performance in a multitude of ways, including decreased health and immunity. Cattle challenged by fescue toxicosis are often grazing in an environment favorable for development of gastrointestinal nematodes (GIN). Interactions of fescue toxicosis and parasite challenge may result in further performance and economic losses. Many beef producers treat animals regularly for GIN parasites with little insight on necessity or effectiveness of anthelmintic products. Overuse of anthelmintics can result in development of anthelmintic resistance in GIN populations. To minimize the development of anthelmintic resistance, implementation of selective deworming practices should be considered. However, level of parasite burden and effects of fescue toxicosis on parasite burden need to be better understood in beef cattle herds before recommendations can be offered. Therefore, the objective was to investigate the impact of fescue toxicosis on GIN parasite infection rates through fecal egg counts (FEC), body weight (BW), hematocrit (HCT), and body condition score (BCS). Starting in April, for 14 consecutive weeks post-weaning, pregnant Angus-based cows (2 to 4 years old, n = 65) were rotationally grazed on either novel endophyte (EN) fescue or endophyte-infected (EI) fescue pastures. Hematocrit, BCS, and BW were assessed weekly, while FEC were measured bi-weekly to monitor the physiological changes as a result of consuming endophyte-infected tall fescue. All data were analyzed using Proc MIXED in SAS with repeated measures. Statistical significance was declared at P ≤ 0.05 and a trend at 0.10 &amp;gt; P &amp;gt; 0.05. Overall, FEC were low (4.2 ± 0.9 eggs/gm) in these mature cattle and grazing EI or EN fescue did not have any overall effect (P &amp;gt; 0.05) on the FEC. However, FEC decreased (P &amp;lt; 0.05) over the course of the study from week 1 to week 13. Body weight, HCT, and BCS were not affected (P &amp;gt; 0.05) by the type of fescue grazed. There was a tendency (P &amp;lt; 0.10) for 2-3 and 4-6 year old cattle to have lower BW when grazing EI compared with EN fescue while cattle &amp;gt;7 were not affected. Cattle gained BW (P &amp;lt; 0.05) over the 14-week study (471.4 and 527.7 ± 0.6 kg, 0 and4 week respectively). For cattle grazing EI fescue, HCT linearly decreased (P &amp;lt; 0.05) from week 1 to week 14 whereas cattle grazing EN fescue had a linear increase (P &amp;lt; 0.05) in HCT from week 1 to week 14. More research is warranted to investigate beef cattle FEC and the potential impact of fescue type on FEC in younger beef cattle.

Incidence of gastro-intestinal strongylosis during monsoon seasons in native goat breeds of Kerala

Gastro-intestinal strongylosis is a major parasitic infection in caprine causing reduced performance, irreversible damage and death, which eventually leads to huge economic loss to the producers. The use of anthelmintics as a simple, effective and quick control method against the parasitism by the farmers has been rampant since decades. But its indiscriminate and undue usage invariably paved way to the development of anthelmintic resistance in parasites. It is high time that control strategies are designed so as to utilise chemotherapy appropriately at the time that coincide with heavy incidence of strongylosis. In the present study, a total of 109 goats, comprising of 58 Malabari and 51 Attappady Black goats from an organised farm were screened for the incidence for strongyle infection. The infection was found to be very high throughout the monsoon seasons in Kerala (June to October) with 94.86 ±1.47 per cent. Majority of the animals exhibited very heavy infection with faecal egg count of (FEC) &gt;1500 during the study period. On coproculture, Haemonchus contortus was found to be the most predominant strongyle followed by Oesophagostomum spp. and Trichostrongylus spp.

A Potential Anthelmintic Phytopharmacological Source of Origanum vulgare (L.) Essential Oil against Gastrointestinal Nematodes of Sheep.

The development of anthelmintic resistance in sheep gastrointestinal nematodes (GINs) requires novel strategies for the sustainable control of these parasites. This study aimed to evaluate the anthelmintic efficacy of the Origanum vulgare (L.) essential oil (EO) against sheep GINs and to evaluate the possibility of its use in control practice. The in vitro egg hatch test was conducted at eight different concentrations (50, 12.5, 3.125, 0.781, 0.195, 0.049, 0.025, and 0.0125 mg/mL) of the tested EO. For the in vivo fecal egg count reduction test, the EO of O. vulgare was administrated orally at a mean single dose of 150 mg/kg to sheep from two farms in Southern Italy, whereby potential toxic effects to the hosts were also evaluated. In the egg hatch test, the inhibition of egg hatchability varied from 71.3% to 93.7%, depending on the concentration used. The high anthelmintic potential was confirmed in the fecal egg count reduction test with an average reduction of nematode eggs in feces of 43.2% and 60.1% on days 7 and 14 after treatment, respectively. In addition, no toxic effects were noticed during the clinical examination of sheep or by observing blood count and liver or kidney function test results. The obtained results suggest the strong activity of the O. vulgare EO against sheep GINs, probably due to a high percentage of carvacrol (76.21%), whereby it can be considered safe for sheep at the dose tested in vivo. Therefore, it is suitable for use in veterinary practice as a part of an integrated strategy for the control of sheep GINs.

Anthelmintic resistance of horse strongyle nematodes to fenbendazole in Lithuania

BackgroundControl of strongyle infections presents a global challenge for horse practitioners due to the development of anthelmintic resistance (AR), however comprehensive information on AR in Lithuania is still lacking. The aim of this study was to assess the current situation of fenbendazole (FBZ) AR in horses at stable level in Lithuania.ResultsFaecal samples from 121 horses from six stables were examined using the Mini-FLOTAC method. Of these, 89 horses met the inclusion criteria that included strongyle faecal egg counts (FEC) exceeding 200 eggs per gram (EPG). Faecal egg count reduction tests (FECRTs) were performed in these. AR was evaluated at horse stable level based on faecal egg count reduction (FECR) and the lower limit of the 95% credible interval (LLCI) using the Bayesian hierarchical model. This study confirmed that strongylids (Cyathostominae (CYA)) resistant to FBZ are pervasive in Lithuania. FBZ was ineffective in three of the six stables (FECR 77.1–79.0%; 49.8–99.8 LLCI), was suspected to be ineffective in one stable (FECR 93.6%; 85.4–100 LLCI) and was effective (FECR 99.8–100%; 99.8–100 LLCI) in two stables. FEC showed a significant (P < 0.01) difference between the treatment and control groups. Only CYA larvae were detected in larval cultures derived from strongyle-positive faecal samples collected 14 days after treatment of a test group with FBZ.ConclusionThis in vivo study showed that resistance to FBZ in the treatment of strongyle nematodes is prevalent in horse stables in Lithuania. These findings should guide the implementation of more sustainable management of strongyle infections in horses in Lithuania.

Potential for silvopastoral systems to control nematode burden in livestock farming in winter rainfall areas of South Australia, Australia

Gastrointestinal nematode infections cause significant production losses in ruminants. In southern Australia, the estimated annual cost of internal parasites in sheep, cattle and goats are $436million, $82m and $2.54m, respectively. An over-reliance on anthelmintic treatments has resulted in anthelmintic resistance becoming an increasing concern for producers. Reducing the need for chemical anthelmintics is desirable to lower producer costs and limit the development of anthelmintic resistance. Condensed tannins found in many trees and forages are a plant secondary compound receiving considerable interest as an alternative anthelmintic strategy. Direct anthelmintic effects from condensed tannins are associated with the binding of larval proteins; slowing egg hatching, larval development and exsheathment. Indirect effects are associated with improvements to protein metabolism and immune function within the animal. Several native Australian tree extracts have demonstrated anthelmintic properties, but further research is required to assess their suitability for silvopastoral systems in South Australia.

Novel compound shows in vivo anthelmintic activity in gerbils and sheep infected by Haemonchus contortus

The control of gastrointestinal nematodes in livestock is becoming increasingly difficult due to the limited number of available drugs and the rapid development of anthelmintic resistance. Therefore, it is imperative to develop new anthelmintics that are effective against nematodes. Under this context, we tested the potential toxicity of three compounds in mice and their potential anthelmintic efficacy in Mongolian gerbils infected with Haemonchus contortus. The compounds were selected from previous in vitro experiments: two diamine (AAD-1 and AAD-2) and one benzimidazole (2aBZ) derivatives. 2aBZ was also selected to test its efficacy in sheep. In Mongolian gerbils, the benzimidazole reduced the percentage of pre-adults present in the stomach of gerbils by 95% at a dose of 200 mg/kg. In sheep, there was a 99% reduction in the number of eggs shed in faeces after 7 days at a dose of 120 mg/kg and a 95% reduction in the number of worm adults present in the abomasum. In conclusion, 2aBZ could be considered a promising candidate for the treatment of helminth infections in small ruminants.

ANTIHELMINTIC POTENTIAL OF CORIANDER ESSENTIAL OIL (CORIANDRUM SATIVUM L.) IN SHEEP

The development of anthelmintic resistance in sheep gastrointestinal nematodes to commercial anthelmintics has led to enormous economic losses in many parts of the world. For this reason, new sustainable strategies for the control of these parasites are being actively searched, which include the use of different alternatives such as plant essential oils. The aim of this study was to determine the chemical composition of the essential oil of coriander (Coriandrum sativum L.) and to test its anthelmintic potential against gastrointestinal nematodes of sheep. Qualitative and semi-quantitative chemical characterization of the essential oil was performed using gas chromatography coupled with mass spectrometric detection (GC-MS analysis). The anthelmintic potential of the essential oil was tested using the in vitro egg hatching test (EHT), which was carried out with eight different concentrations of the tested oil (50; 12.5; 3.125; 0.781; 0.195; 0.049; 0.025 and 0.0125 mg/mL). Thiabendazole in concentrations of 0.025 and 0.0125 mg/mL was used as the positive control, and the emulsifier 3% Tween 80 v/v and distilled water was used as the negative control. GC-MS analyzes revealed a rich chemical composition of the tested oil, where a total of 17 different ingredients from different chemical groups were found, of which 15 were identified. The dominant ingredient was linalool (84.5%) along with γ-terpinene (5.04%),camphor (3.26%) and α-pinene (2.88%). The EHT results showed a high anthelmintic potential of coriander oil with inhibition of larval hatching, i.e. an ovicidal effect of 29.0-88.7% depending on the concentration, with an IC50 concentration of 0.04 mg/mL and a clear dose-dependent effect (R2= 0.90). This study confirmed the possible importance of botanical anthelmintics in the sustainable control of nematodes in animals and the fight against anthelmintic resistance. The obtained results indicate a possible role of coriander in future therapeutic approaches to infections caused by gastrointestinal nematodes of sheep, after further in vivo tests and toxicity studies.

In Vitro Anthelmintic Activity of Sea Buckthorn (Hippophae rhamnoides) Berry Juice against Gastrointestinal Nematodes of Small Ruminants

Simple SummaryGastrointestinal nematodes are included worldwide among the most prominent parasites of small ruminants. In past decades, the control of these nematodes mainly relied on the use of synthetic anthelmintic drugs. However, nowadays the exclusive use of anthelmintic drugs is considered an obsolete and unsustainable control strategy due to the onset of anthelmintic-resistant sheep gastrointestinal nematode strains and the issues linked with the environmental pollution and residues in food of animal origin of synthetic anthelmintic drugs. Among alternative or complementary methods, the use of plants endowed with anthelmintic properties has been identified as a valuable option. As a part of this approach, this study evaluated the in vitro anthelmintic properties of two commercial sea buckthorn (Hippophae rhamnoides) berry juices on sheep gastrointestinal nematodes. Both H. rhamnoides berry juices tested in this study showed interesting anthelmintic properties in vitro. The obtained results are promising regarding the use of sea buckthorn berry juice as a potential tool for the control of gastrointestinal nematodes in small ruminants.Gastrointestinal nematodes are one of the major threats in small ruminant breeding. Their control is difficult due to the development of anthelmintic resistance, and the search for new molecules endowed with anthelmintic activity (AH) is considered a priority. In this context, we evaluated the in vitro AH activity of two commercial sea buckthorn (Hippophae rhamnoides) berry juices, namely SBT and SBF. The in vitro evaluation was based on the egg-hatch test and larval exsheathment assay at different concentrations. Data were statistically analysed, and the EC50 was calculated. Chemical analyses were performed to evaluate the total polyphenol content of the juices and chemical profile of the most represented compounds. The role of the polyphenolic fraction in the anthelmintic activity of the juices was also assessed. At the highest concentrations, the activity of SBT was high in both tests and comparable to that observed in the thiabendazole-treated positive controls, while SBF showed a lower efficacy. Glycosylated isorhamnetin and quercetin were the most represented polyphenolic compounds in both juices. In conclusion, both H. rhamnoides berry juices tested in this study showed interesting anthelmintic properties in vitro.

Farmers' perception on the control of gastrointestinal parasites in organic and conventional sheep production in Sweden.

A questionnaire was sent to sheep owners in Sweden to get information about anthelmintic drug use. The survey also investigated how respondents experienced problems with gastrointestinal nematode infections (GIN) focusing on Haemonchus contortus. The response rate was 31% and included both conventional and organic farms. The use of anthelmintics was low (45%), among which a majority (76%) drenched ewes on a single occasion, mostly with ivermectin (59%) followed by albendazole (19%). Other drugs were used rarely, however, unawareness of GIN risk was high (19%), especially among respondents with few animals. Anthelmintic dose calculations were done after visual appraisal by 63% and 22% calibrated the equipment before drug delivery, which is worrying since underdosing is a risk factor for the development of anthelmintic resistance. Like with anthelmintics, the perceived risk for GIN increased with herd size both by conventional and organic farmers. Faecal examination for the presence of GIN was done by 65% of the respondents and, among their sheep, H. contortus was or had been diagnosed in 41% of the herds. Irrespective of new stock had been imported from other countries or not, common problems were reported by 5% and 7% of the organic and conventional producers, respectively. Land use and grazing management strategies differed more in relation to herd size than by production form, with a majority (47%) having their sheep grazed in several paddocks, or at least the lambs were moved when separated from the ewes at weaning (25%). In contrast set stocked grazing was mainly reported on smaller farms. Co-grazing with cattle and horses were also frequently reported irrespective of production form, but with cattle to a somewhat greater degree on larger organic farms. Wild cervids, especially roe deer, were frequently observed on sheep pastures (87%). The veterinary involvement was higher on organic (65%) than on conventional farms (53%), and only 5% considered advice unimportant. Still, some conventional and organic producers treated sheeps routinely without a prior diagnosis, against the national regulations. 46% of the respondents drenched new and replacement stock. In conclusion, although some differences were observed between conventional and organic producers, the divergences were mainly due to herd size categories. Furthermore, despite a high veterinary involvement, we identified factors which can contribute to anthelmintic use, such as poor quarantine procedures, and deworming routines that can contribute to anthelmintic resistance in H. contortus.

NEMATODE EGG RE-APPEARANCE PERIOD AFTER ANTHELMINTIC THERAPY IN HORSES IN THE MOSCOW REGION

The research purpose is studying early signs of the anthelmintic resistance development in equine nematode population on horse farms. This is possible with reference to the egg-reappearance period (ERP) after the treatment. The study was performed in the Moscow Region in 2020–2021. The horses were examined by the flotation method before the therapy. The data obtained made it possible to divide the animals into 5 experimental groups. Groups 1–2 included horses infected by strongyles. The treatment was given with Albendazole and Ivermectin. Groups 3–5 included horses infected with Parascaris equorum; they were treated with Fenbendazole, Ivermectin and Aversectin C. All horses from the experimental groups were examined on days 14, 42 and 84. Benzimidazoles and Aversectin C showed no ERP reduction. Despite the fact that Albendazole did not show 100% efficacy and an increase in eggs appeared in faeces of the horses began from day 42 (from week 6), these data correspond to the literature data on the ERP during the Albendazole therapy and do not indicate the development of any anthelmintic resistance. After Ivermectin, the growth of Strongylid and Parascaris eggs was detected in faeces of the horses on day 42 (from week 6), which was an ERP reduction as compared with the literature data at 9 weeks. The study was supported by the grant from the Russian Science Foundation (Project No. 20-76-00035).