Gastrointestinal Nematodes Research Articles

114 The efficacy of a natural fungus (Duddingtonia flagrans) in reducing gastrointestinal nematode indicators in lambs

Abstract Sustainable and profitable small ruminant production in the US is affected by infections with gastrointestinal nematodes (GIN), especially the blood sucking GIN, Haemonchus contortus. The overuse and misuse of available drug classes has led to multi-drug resistant GIN that pose significant challenges to parasite control on many farms. The objective of this study was to evaluate the effectiveness of a natural fungus (Duddingtonia flagrans; Bioworma, International Animal Health) in reducing GIN larval counts and other GIN indicators in hair sheep wethers. Eighteen St. Croix (n = 9) and Barbados Blackbelly (n = 9) wethers (227 ± 1.4 days of age and 29.7 ± 0.6 kg BW) were dewormed (d 0) with a combination of levamisol (Prohibit; 8 mg/kg BW) moxidectin (Cydectin; 0.2 mg/kg BW) and albendazole (Valbazen; 7.5 mg/kg BW) prior to the start of feeding according to the manufacturer’s recommendations for feeding BioWorma. At this time, lambs were separated into two treatment groups (n = 9/group), split into 3 replications per treatment group and placed on six pasture paddocks (0.06 ha; n = 3 per paddock) after accounting for breed, initial fecal egg count (FEC) and BW. Lambs were then fed daily either a grain supplement ration (corn and soybean meal) with Livamol with Bioworma (LIV) or without (CON) at 2% of their BW for 98 d. LIV was added to the ration based on total lamb BW/paddock. To evaluate the effect of LIV treatment, BW and body condition scores (BCS) were recorded every 2 wk for 98 d. Blood and fecal samples were also collected for determination of packed cell volume (PCV) and FEC. Pooled treatment group feces (d 0 – 98) were collected and cultured to determine GIN genera. A subset of animals/treatment (n = 3) will be harvested to determine abomasal worm counts. Data were analyzed using repeated measures in a mixed model, and FEC were log transformed before analysis. Following deworming (d 0), FEC were reduced by 100% by d 14. There was a mixed population of GIN at the start of the study (averaging 54%, 42%, 1.2% and 1.8% for H. contortus, Tricostrongylus spp., Oesphagostomum spp. and Nematodirus spp., respectively). LIV with Bioworma supplementation had no impact on BW, BCS, PCV or FEC in this study averaging 34.2 ± 0.3 kg, 2.5 ± 0.04, 34.7 ± 0.5% and 150.9 eggs per gram, respectively. Under the conditions of this study, Bioworma® supplementation had no influence on GIN indicators measured up to 100 d of grazing. This research will be continued during subsequent grazing seasons to determine the effect of continued supplementation on lamb parasite load and performance as well as pasture infestation levels.

58 United States Department of Agriculture National Animal Health Monitoring System Goat 2019 study: Distribution of gastrointestinal nematodes

Abstract One objective of the United States Department of Agriculture National Animal Health Monitoring System Goat 2019 study was to describe practices producers use to control gastrointestinal nematodes (GIN) and reduce anthelmintic resistance through the examination of anthelmintic treatment efficacy via fecal egg count reduction tests and fecal cultures. The fecal cultures were used to determine what GIN were present across the areas of the US included in the study (September 2019-April 2020). Bulk cultures were processed from 318 operations in 24 states and results were consolidated into 4 regions: Northwest (3 states, 34 operations), Northeast (9 states, 89 operations), Southeast (9 states, 132 operations) and Southwest (3 states, 63 operations). GIN identification included Haemonchus, Trichostrongylus, Teladorsagia, Oesophagostomumand Nematodirus. In addition to GIN, lungworm presence was also noted. Haemonchus were found on 18.6% of the operations (Northwest, 27.0%; Northeast, 13.1%; Southeast, 15.9% and Southwest, 29.2%). Trichostrongylus were found on 97.2% of the operations (Northwest, 100%; Northeast, 98%; Southeast, 97.0% and Southwest, 95.7%). Teladorsagia were found on 80.3% of the operations (Northwest, 97.1%; Northeast, 71.6%; Southeast, 88.6% and Southwest (75.7%). Oesophagostomum were found on 38.2% of the operations (Northwest, 73.1%; Northeast, 39.6%, Southeast, 46.4% and Southwest, 15.5%). Nematodiruswere found on 7% of the operations (Northwest, 7%; Northeast, 5.2%, Southeast, 20.8% and Southwest, 0%). Lungworms were found on 35.4% of the operations (Northwest, 69.1%; Northeast, 52.2%, Southeast, 33.4% and Southwest, 8.3%). Due to sampling logistics, fecal collection was conducted during autumn through early spring which may have influenced number of more pathogenic GIN. This study provided valuable insight into regional prevalence of GIN in goats. In depth analyses continues and will be forthcoming.

84 Efficacy of Livamol with BioWorma for controlling gastrointestinal nematode in nursing Kiko does raised in pastures

Abstract Prevalence of gastrointestinal nematodes (GINs) has become a critical issue because of nematode resistance to anthelmintics available in the market. Livamol with BioWorma (hereafter BioWorma), a biological product containing spores of Duddingtonia flagrans, is known to trap GIN larvae and reduce the chance of re-infection in artificially-infested animals. However, the efficacy of this product is not known in pasture-raised nursing does acquiring natural challenges of GIN through contaminated pastures. The objective of this study was to evaluate the effectiveness of BioWorma for controlling GIN in pasture-raised nursing does. The study was conducted for 120 d (March-August 2023). Sixteen nursing Kiko Does and kids (n = 30) were divided into two uniform groups. Each group of animals was assigned to separate sets of grazing plots and rotationally stocked in those plots throughout the study. Animals had free access to clean drinking water, shelters, and mineral mix in each plot. BioWorma at the rate of 1g/d/kg of animal body weight (BW) was fed to one group of animals. BioWorma was mixed with 0.227 kg of whole corn before feeding. Another group (control) was provided with an equivalent amount of corn without BioWorma. Additionally, both groups were supplemented with whole corn at the rate of 0.5% BW. Animal performance data [BW, body condition score (BCS), and FAMACHA score] and fecal samples were taken on d 1, every week during the study, and the last day of the study. Fecal samples were analyzed to determine the egg per gram (EPG). Blood samples were taken on the first day of the study, then every month during the study, and on the last day of the study. Blood samples were analyzed in ProCyte Dx Analyzer for hematological parameters (RBC, hematocrit, hemoglobin, WBC, neutrophil, eosinophil, monocytes, basophil, and platelets) and in Catalyst Dx for biochemical parameters (glucose, creatine, blood urea nitrogen, Ca, P, Na, Cl, and other parameters). Animal performance and blood profile data were analyzed using the GLM procedure and EPG data using the Wilcoxon Rank-Sum test in SAS 9.4. Overall, the treatment group had less EPG (35%; P < 0.05) than the control group. However, the consistent trend of BioWorma reducing EPG was not found when data were analyzed for each observation date. BioWorma had no significant impact on BW, FAMACHA score, BCS, and blood parameters. Results showed that BioWorma was able to reduce the overall GIN EPG in nursing Kiko does raised in pastures. Long-term research on the efficacy of BioWorma in controlling GIN in goats will reveal more useful information.

73 Deworming to improve growth in early-weaned spring born hair sheep lambs

Abstract In lambs, the stress of weaning and the lack of a fully developed immune system can increase susceptibility to gastrointestinal nematodes (GIN). Lack of an effective GIN control strategy around this time can have a significant impact on lamb growth, productivity and mortality. The objective of this study was to determine the influence of deworming at weaning on growth performance in hair sheep lambs. St. Croix (STX) and Barbados Blackbelly (BB) lambs used in the study were born on pasture, weaned at 60.2 ± 0.4 d of age, and transitioned in pens for 87 d post-weaning before turning out to pasture. After accounting for initial FAMACHA eyelid color score, breed, and birth type (single or multiple) at weaning, 54 STX (n = 32) and BB (n = 22) lambs weighing 11.7 ± 0.4 kg were dewormed (DEW) or not (CON) with a combination of levamisol (Prohibit; 8 mg/kg BW) moxidectin (Cydectin; 0.2 mg/kg BW) and albendazole (Valbazen; 7.5 mg/kg BW). To evaluate the effect of deworming treatment, BW and body condition scores (BCS; scale 1-5) were recorded at weaning and at end of transition to pasture. Blood and fecal samples were also collected for determination of packed cell volume (PCV) and fecal egg counts (FEC). Pooled treatment group feces (d 0 – 98) were collected and cultured to determine GIN genera at weaning. Data were analyzed using repeated measures in a mixed model, and FEC were log transformed prior to analysis. There was a mixed population of GIN at weaning averaging 65% and 35% for H. contortus and Tricostrongylus spp. At weaning, BCS, PCV, and FEC were similar between treatment groups and averaged 1.6 ± 0.07, 36.5 ± 0.6%, and 399 ± 54.4 epg, respectively. Combination deworming reduced FEC by 99%. At turnout, DEW lambs (2.3 ± 0.1) tended (P = 0.08) to have greater BCS than CON lambs (2.0 ± 0.1) and PCV was greater (P < 0.001) in DEW versus CON lambs (37.2 ± 0.9 and 33.3 ± 0.8%, respectively). There was also a tendency (P = 0.09) for breed to influence BCS (2.3 ± 0.1 and 2.0 ± 0.1 for BB and STX, respectively). The FEC at turnout was not influenced by treatment or breed (496.7 ± 75.1 epg). Additionally, DEW lambs (131.8 ± 5.2) tended (P = 0.09) to grow faster than CON (119.9 ± 4.7 g/d) lambs, a difference more pronounced in STX DEW (g/d) than STX CON lambs (136 ± 6.1 vs 110 ± 6.5 g/d; P < 0.05). Even though deworming tended to promote faster growth rates in lambs used in this study, alternative, more sustainable, parasite control strategies should be considered in the wake of increasing dewormer resistance.

117 Supplementation with soy hull during late gestation and lactation on parasite indicators in hair sheep ewes

Abstract Before lambing and up to 8 wk during lactation, ewes experience a temporary loss of immunity to gastrointestinal nematodes (GIN). This can result in a periparturient increase in fecal egg counts (FEC) along with clinical symptoms of parasitism. This increase in FEC can lead to greater larval numbers on pasture, consequently exposing lambs to a greater level of infection that can impair production. Adequate supplementation during late gestation and lactation has been shown to reduce the impact of this temporary loss in immunity and decrease GIN infection levels in ewes. This study evaluated the supplementation of an agro-byproduct (soy hull) on GIN infection parameters in hair sheep ewes. Pregnant ewes (n = 36) were allocated, balanced by breed, parity and fetal numbers to either corn/soybean (CS) or soy hull (SH) supplementation during the last trimester of pregnancy. Ewes rotationally grazed predominantly fescue pastures subdivided into 6 sections (0.13 ha) using electro-netting (3 sections of 6 ewes/supplement type). Ewes were supplemented at either 0.75% BW (late gestation) or 1.5% BW (lactation) using a single feeder per section. Ewes lambed on pasture and lambs were weaned at approximately 63 d. Lambs had access to the supplement provided to their dams. Blood and fecal samples were collected in prepartum, postpartum and at weaning for determination of packed cell volume (PCV) and FEC. Pooled treatment group feces were also collected and cultured to determine GIN genera. Body condition scores (BCS) were also recorded at each sampling. Data were analyzed in a model with supplement type and breed as the main effects and FEC were log transformed before analysis. There was a mixed population of GIN throughout the study with H. contortus (49.5%) and Tricostrongylus spp. (46.6%) being the most common. Supplement type had no effect on ewe BCS prepartum, postpartum or at weaning (averaging 2.6 ± 0.1, 2.3 ± 0.1 and 2.0 ± 0.1, respectively). Supplement type influenced PCV at weaning only, with ewes supplemented with CS having a greater (P < 0.03) PCV than those supplemented with SH (33.0 ± 0.7% and 30.8 ± 0.7%, respectively). PCV was similar between treatments prepartum (38.4 ± 1.3%) and postpartum (34.4 ± 0.9%). Ewe FEC was similar between CS and SH supplemented ewes prepartum (271.6 ± 0.5 epg) and at weaning (298.5 ± 80.5 epg); however, at postpartum sampling CS ewes tended (P = 0.09) to have reduced FEC (234.1 ± 62.0 epg) compared with SH (414.1 ± 59.6 epg) supplemented ewes. At weaning, lamb FEC was not influenced by supplementation or breed and averaged 502.3 ± 83.2 epg. Data indicate that substituting SH for a more traditional corn-based supplement in landrace hair sheep ewes managed in a pasture-based system had no influence on GIN infection. Agro-byproduct supplementation should be explored further for their use in sustainable, forage-based sheep production systems.

66 Effect of copper oxide wire particles on parasitism and growth in Katahdin lambs divergently selected for fecal egg count estimated breeding value

Abstract Internal parasites are one of the greatest threats to small ruminant production across the United States and parasitic resistance to anthelmintics continues to increase. Genetic selection and copper oxide wire particles (COWP) are two tools that could help reduce effects of parasites in small ruminants. The objective of this project was to determine the effects and interactions of COWP and genetic selection based on fecal egg count (FEC) estimated breeding value (EBV) on gastrointestinal nematode (GIN) infection and performance in naturally infected Katahdin lambs. Spring-born Katahdin ram lambs (n = 52) selected for extremely high FEC EBV (HighFEC, PFEC EBV = +100%) or low FEC EBV (LowFEC, PFEC EBV = -81%) were managed on a fescue-based pasture at the Southwest Virginia Agricultural Research and Extension Center (Glade Spring, VA). At weaning (June 29), lambs were dewormed with a three-combination treatment and rested for 21 d. At the start of the project (July 18), a random subset of lambs (HighFEC, n = 11; LowFEC, n = 15) were given a 2 g copper oxide wire particle bolus, while an equal number of remaining lambs were managed as controls without a copper bolus. All lambs were managed as one contemporary group. Fecal egg counts, FAMACHA scores, body weights, and packed cell volume (PCV) were measured bi-weekly for 10 weeks. Statistical analysis was performed using PROC Mixed Procedure of SAS (SAS Institute, Cary, NC) and FEC data were log transformed for normality. There were no effects of COWP treatment on FEC (P = 0.18). However, LowFEC-selected lambs had less FEC than HighFEC-selected lambs (230 vs. 565 eggs/g, respectively; P < 0.01). There was no interaction of COWP treatment and FEC genotype (P = 0.37). Copper oxide wire particle treatment had no effect on lamb body weight (P = 0.21), PCV (P = 0.69), FAMACHA score (P = 0.41), or overall ADG (P = 0.12). Lamb FEC genotype did not affect FAMACHA score or overall ADG (P = 0.10 and P = 0.22, respectively). LowFEC-selected lambs had lighter body weights (27.7 vs. 30.6 kg, respectively) and PCV (29.2% vs. 30.4%, respectively) than the HighFEC-selected lambs (P < 0.05). None of the 52 lambs met the requirement for deworming (FAMACHA ≥ 3) during the study. These results indicate that lamb FEC genotype may have a greater effect on parasitism than COWP treatment when given once during the post-weaning period. Even so, multiple tools should be considered, in addition to selection, for an integrated parasite management plan.

64 The effect of postweaning fecal egg count EBV on colostrum IgG concentration and color in Katahdin dams

Abstract Selection for postweaning fecal egg count (PFEC) EBV has revealed that low-PFEC sheep have greater resistance to gastrointestinal nematode infection, greater survivability to weaning, and greater anamnestic response to booster clostridial vaccination. Therefore, it can be hypothesized that selection for PFEC may result in improved generalized immunity. It has also been reported that good-quality colostrum has a thick consistency and yellowish color. Thus, the aim of this study was to compare IgG concentration and color of colostrum in Katahdin ewes divergent in their PFEC EBV. All lactating ewes at the SWAREC were analyzed and were sorted into three groups: low-PFEC (PFEC < -50, n = 39), mid-PFEC (-49 < PFEC < +49, n = 38), and high-PFEC (PFEC > +50, n = 23) and sampled within 6-h post-partition. Upon parturition, a 20 mL colostrum sample was sterile collected by milking 10 mL from each udder half of the ewes; all samples were placed into pre-labeled 50 mL tubes and frozen on-site. Colostrum samples were thawed and diluted in 36% ammonium sulfate and centrifuged at 3,000 x g for 20 min at 4ºC. The removed whey portion was dialyzed using a 3,000 MW membrane cassette in 1 L of PBS (pH 7.4) at 4ºC for 12 h. Total IgG from colostrum was measured using an ovine-specific enzyme-linked immunosorbent assay (ELISA), and color parameters were measured using a Minolta chromameter. To evaluate IgG and color differences, data were analyzed using the General Linear Model (GLM) procedure of SAS with Tukey’s HSD test to compare the effects of ewe PFEC genotype on colostrum IgG, Yellowness Index (YI), Whiteness Index (WI), L*, b* and a* values. Main effects of ewe PFEC genotype displayed a stepwise decrease in average colostrum IgG from low-PFEC to high-PFEC groupings (825 ng/mL, 513 ng/mL, and 258 ng/mL, respectively; P < 0.0429). Likewise, a stepwise decrease in b* value, indicating relative yellowness, occurs from low-PFEC to high-PFEC groups (18.97, 16.91, and 15.22, respectively; P < 0.0459). These data suggest low-PFEC Katahdin ewes generate greater antibody concentration and yellowness within colostrum. Therefore, lambs born to these ewes would have a significant advantage in passive immunity from their dams, potentially contributing to lamb survivability.

61 Determining in vivo and in vitro predatory activity of Duddingtonia flagrans and interaction with dietary coccidiostat

Abstract A nematode trapping fungus, Duddingtonia flagrans (Df), fed to sheep is useful for biocontrol of gastrointestinal nematodes on pasture. The objectives were: 1) validate methods to determine viability of a commercial source of Df before beginning research studies, and 2) examine the interaction between Df and dietary coccidiostat (as decoquinate). Methods: Study 1: In Jan 2023, weaned Katahdin lambs (97.3 ± 1.2 d of age; 19.5 ± 1.3 kg BW; packed cell volume of 26.5 ± 1.4 %), naturally infected with predominantly Haemonchus contortus (89%) and mean fecal egg count (FEC) of 6,860 ± 1,535 eggs/g, were randomly assigned to: 1) no Df (-g)/(FEC-g)×100]. Study 2: In Aug 2023, 7 mo old anthelmintic-treated ram lambs (FEC < 50 egg/s; 51.6 ± 3.9 kg in BW) were fed grain supplement daily with decoquinate (Deccox; +C) or without (-C; n = 3/diet) on d -7 to 1, and, within diet, administered 3 g BioWorma/d in 6 gel capsules (+DF; n = 2/diet) or not (-DF; n = 1) on d -1 and -2. Fecal samples were collected on d 0 (2 g/plate + 300 L3 of H. contortus) and d 1 (6 g/plate + 1000 L3) and placed on water agar plates (n = 3/lamb) at 25°C. Trapping structures were visually assessed after 24, 48, and 144 h (6 d), and cultures Baermannized on d 7 for L3 recovery. Relative reduction was (x̅-DF-C-x̅+DF+C/ x̅-DF-C)×100%. Data for variables collected one time were analyzed by Proc GLM (SAS), and for those collected serially, a Proc Mixed with repeated measures. A 2×2 factorial was used in Study 2 and included treatments, day and interaction in model. Results: Study 1: As expected, L3 recovery was reduced (P = 0.005) in DF lambs by 67-78% relative to control. Study 2: DF formed loops and traps around L3 by d 6 and reduced L3 recovery on both days (P < 0.001) without an interaction by decoquinate (P = 0.69). The L3 reduction relative to -DF-C was between 60.2-73.5%. The coccidiostat, decoquinate, can be added to the diet in the presence of BioWorma without antagonism. In conclusion, the in vitro studies allow detection of adverse issues with viability of Df and can reduce the number of animals needed for research studies.

75 AI-Enhanced Hematocrit Analysis: Revolutionizing rapid anemia detection in small ruminants

Abstract In recent times, there has been a growing focus on the well-being and healthcare of small ruminants, particularly in relation to the issue of anemia due to infection with blood-feeding gastrointestinal nematodes, such as Haemonchus contortus. The objective of this study was to assess the hematocrit levels in blood samples obtained from small ruminants, specifically goats. Additionally, the study is an attempt to design and create a quick sensor for identifying anemia, which could be conveniently used on farms. A total of 75 mature, intact male Spanish goats were subjected to hematocrit analysis to ascertain their spectrum of hematocrit values and association with anemic conditions. Simultaneously, a unique sensor with user-friendly features was developed to promptly provide farmers with feedback on the anemic status of animals using AI-based machine learning algorithms, enabling timely intervention. The sensor utilized a semi-invasive approach with minimal blood sample requirement. 30 µL of blood was dropped on glycerol soaked Whatman filter paper No. 1, and images were taken at 90 sec, 150 sec, and 270 sec to capture the blood pattern on filter paper soaked in glycerol using a cell phone. These images were correlated with actual hematocrit value obtained from conventional hematocrit analysis. A RMSprop with adjusted learning rate convolution neural network (RMSprop-CNN) based images classification model was developed for the classification of different patterns at different levels of hematocrit. The model was trained on a total of 1,000 images with a training and testing split of 80:20 ratio. For the optimization process, the Adam optimizer with a learning rate of 0.001 is employed. The model is compiled with a categorical cross-entropy loss function, aiming to improve its accuracy metric over training iterations. The initial studies demonstrated a detection accuracy level of 70.31 % at 10 epochs in identifying different hematocrit levels (Level 1; healthy, to Level 5; severely anemic) but improved significantly up to 94.89 % by 100 epochs, resulting in a notable reduction in the time and level of knowledge previously necessary for conducting such evaluations. The present study not only provides valuable insights into the hematological characteristics of small ruminants, but also establishes a foundation for the development of a straightforward and efficient method for detecting anemia. Consequently, this advancement has the potential to enhance the overall care and well-being of animals within agricultural environments.

Utilisation of indigenous knowledge to control gastrointestinal nematodes in Southern Africa

Gastrointestinal nematodes (GIN) exacerbate the impact of droughts on the survival of cattle. The inadequacies of the conventional system make it increasingly important to explore indigenous knowledge (IK) to create drought-tolerant and GIN resilient herds. The objective of the study was to assess the indigenous strategies for controlling GIN during droughts. Face-to-face interviews with experts on IK were conducted to give insight into the importance, methods and ranking of GIN control. The experts identified 86 cattle that were used to test their assertions. The control methods used were identifying cattle that were susceptible to high GIN loads using predisposing factors, diagnosis of GIN burdens using faecal appearance, and treatment using phytotherapy. Experts ranked predisposing factors as the most critical control strategy and identified body condition, class, sex, coat colour, pregnancy status and lactation status as predisposing factors to high GIN burdens. Thin, older, dark-coloured cattle, as well as pregnant and lactating cows, were considered susceptible to GIN. However, pregnancy status, coat colour and sex were significantly associated with high GIN burdens. Cows were 2.6 times more likely to have high GIN burdens than bulls. Dark-coloured cattle were 3.5 times more likely to have high GIN burdens than light-coloured ones, and the likelihood of pregnant cows was 4.9 times higher than non-pregnant cows. A dark-coloured pregnant cow was extremely susceptible to high GIN burdens. In conclusion, knowledge of predisposing factors informs selection decisions when purchasing foundation stock. Cattle that are susceptible to high GIN loads are prioritised during droughts or culled where resources are scarce.

Phytochemical analysis and anthelmintic activity of Combretum mucronatum leaf extract against infective larvae of soil-transmitted helminths including ruminant gastrointestinal nematodes

BackgroundSoil-transmitted helminths (STH) infect more than a quarter of the world’s human population. In the absence of vaccines for most animal and human gastrointestinal nematodes (GIN), treatment of infections primarily relies on anthelmintic drugs, while resistance is a growing threat. Therefore, there is a need to find alternatives to current anthelmintic drugs, especially those with novel modes of action. The present work aimed to study the composition and anthelmintic activity of Combretum mucronatum leaf extract (CMLE) by phytochemical analysis and larval migration inhibition assays, respectively.MethodsCombretum mucronatum leaves were defatted with petroleum ether and the residue was extracted by ethanol/water (1/1) followed by freeze-drying. The proanthocyanidins and flavonoids were characterized by thin layer chromatography (TLC) and ultra-high performance liquid chromatography (UPLC). To evaluate the inhibitory activity of this extract, larval migration assays with STH and GIN were performed. For this purpose, infective larvae of the helminths were, if necessary, exsheathed (Ancylostoma caninum, GIN) and incubated with different concentrations of CMLE.ResultsCMLE was found to be rich in flavonoids and proanthocyanidins; catechin and epicatechin were therefore quantified for standardization of the extract. Data indicate that CMLE had a significant effect on larval migration. The effect was dose-dependent and higher concentrations (1000 µg/mL) exerted significantly higher larvicidal effect (P < 0.001) compared with the negative control (1% dimethyl sulfoxide, DMSO) and lower concentrations (≤ 100 µg/ml). Infective larvae of Ascaris suum [half-maximal inhibitory concentration (IC50) = 5.5 µg/mL], Trichuris suis (IC50 = 7.4 µg/mL), and A. caninum (IC50 = 18.9 µg/mL) were more sensitive to CMLE than that of Toxocara canis (IC50 = 310.0 µg/mL), while infective larvae of Toxocara cati were largely unaffected (IC50 > 1000 µg/mL). Likewise, CMLE was active against most infective larvae of soil-transmitted ruminant GIN, except for Cooperia punctata. Trichostrongylus colubriformis was most sensitive to CMLE (IC50 = 2.1 µg/mL) followed by Cooperia oncophora (IC50 = 27.6 µg/mL), Ostertagia ostertagi (IC50 = 48.5 µg/mL), Trichostrongylus axei (IC50 = 54.7 µg/mL), Haemonchus contortus (IC50 = 145.6 µg/mL), and Cooperia curticei (IC50 = 156.6 µg/mL).ConclusionsThese results indicate that CMLE exhibits promising anthelmintic properties against infective larvae of a large variety of soil-transmitted nematodes.Graphical

Epigenetic Investigation Related to Gastrointestinal Helminth Resistance and Performance in Cattle

Abstract The objective was to characterize a herd of 73 Nellore heifers, identifying resistant, resilient, and susceptible animals to gastrointestinal helminths, relating the global methylation of the DNA of these animals with the degree of helminthiasis and factors that interfere with performance. Individual count of eggs per gram of feces (EPG), fecal culture for gender identification, weighing and blood sampling were carried out to determine PCV, STP, EOS, IgG, followed by DNA extraction and methylation analysis. The results were: 47% resistant animals, 34% resilient, and 19% susceptible to gastrointestinal helminth infections, with EPG counts of 53, 216, and 841, respectively, showing a statistical difference between all groups. The quantification of DNA methylation was 0.311, 0.245 and 0.178, respectively, for resistant, resilient, and susceptible animals, with a correlation being found between resistance to gastrointestinal helminths and overall DNA methylation. For weight gain, resistant and resilient animals showed higher values than susceptible ones, with a correlation between weight gain and EPG. The same was observed for VG; however, there was no statistical difference to the EOS, PPT, and IgG values. A significant correlation was found between PCV and EPG; quantifications of PCV and methylated DNA, STP and EPG; VG and STP. Therefore, the methodologies used made it possible to identify the animals regarding the degree of infection by gastrointestinal nematodes, making it possible to correlate the resistance of cattle to helminths with the amount of global DNA methylation and its performance.

Anthelmintic efficacy of nitazoxanide in dogs naturally infected with Toxocara canis.

Toxocara canis (T. canis) is a gastrointestinal nematode in dogs, and its larvae also infect humans, causing severe larval migratory disease. Anthelmintic drugs have become the primary means to combat T. canis. In this study, the efficacy of nitazoxanide (NTZ) was tested against all the internal stages of T. canis, including L3 larval stage in vitro experiments and gastrointestinal worm in vivo experiments. In the in vitro experiment, after treatment with NTZ at 7.81 and 62.5 μg/mL for 12 h, the larval mortality efficacy reached 90.0 and 100.0%, respectively. In the in vivo experiments, 100 mg/kg NTZ possessed good anthelmintic efficacy against T. canis, with an egg per gram (EPG) reduction of 99.19%, and 90.00% of dogs cleared with residual worms. These results were comparable to those of the positive control drug. The highest anthelmintic efficacy was observed in the group treated with 150 mg/kg NTZ. Based on faecal egg counts, the number of T. canis eggs decreased by 100.00%, and the percentage of dogs cleared with residual worms achieved 90.00% after 7 days of treatment in the 150-mg/kg NTZ treatment group. In general, NTZ showed great potential to be applied as an anthelmintic against T. canis.

Introduction to Strongyloides stercoralis Anatomy.

Strongyloides stercoralis, commonly known as the human threadworm, is a skin-penetrating gastrointestinal parasitic nematode that infects hundreds of millions of people worldwide. Like other Strongyloides species, S. stercoralis is capable of cycling through a single free-living generation. Although S. stercoralis and the free-living nematode Caenorhabditis elegans are evolutionarily distant, the free-living adults of S. stercoralis are similar enough in size and morphology to C. elegans adults that techniques for generating transgenics and knockouts in C. elegans have been successfully adapted for use in S. stercoralis. High-quality genomic and transcriptomic data are also available for S. stercoralis. Thus, one can use a burgeoning array of functional genomic tools in S. stercoralis to probe questions about parasitic nematode development, physiology, and behavior. Knowledge gained from S. stercoralis will inform studies of other parasitic nematodes such as hookworms that are not yet amenable to genetic manipulation. This review describes the basic anatomy of S. stercoralis.

Influence of environmental factors on the occurrence of gastrointestinal and cardiopulmonary nematodes in the red fox in the semi-arid Mediterranean areas of the Iberian Peninsula

Human-induced ecosystem fragmentation is one of the drivers causing wildlife migration from their natural habitats to urban areas, among other reasons. The red fox (Vulpes vulpes) is the most abundant wild canid in the semi-arid Mediterranean areas of the Iberian Peninsula. Water scarcity may result in areas shared by synanthropic fox populations and domestic animals becoming hotspots for parasite transmission. This study describes the gastrointestinal and cardiopulmonary nematode species affecting fox populations in these semi-arid areas and the influence of environmental variables on parasite abundance. A total of 167 foxes collected from 2015 to 2021 in the Region of Murcia (SE Spain) were analysed. Parasite abundance and spatial distribution were evaluated using environmental variables and host characteristics with a Generalised Linear Model and the Moran index. Eleven species (seven from the gastrointestinal tract and four from the cardiopulmonary tract) were described. The influence of biotic and abiotic variables was studied for Angiostrongylus vasorum, Crenosoma vulpis, Uncinaria stenocephala, Toxocara canis and Toxascaris leonina. Temperature, humidity and areas of forest or agricultural land influenced the abundance of these parasites, providing optimal conditions for free-living stages of the direct life cycle nematodes and intermediate hosts. Absolute abundance distribution maps showed defined locations for C. vulpis, T. canis and T. leonina. The results for U. stenocephala, T. canis and T. leonina were particularly important as their higher abundance levels were found close to anthropized areas, which need to be carefully evaluated to prevent transmission of these nematodes between domestic and wild canids and human health.

Modified technique for recovery of nematode infective larvae in different grass genera

Most gastrointestinal nematodes are in the grazing environment. As an option, the study aimed to evaluate an alternative technique for recovery of infecting larvae in various grass genera: Tyfton 85 (Cynodon dactylon) Capim–Vencedor (Megathyrsus maximus) Capim–Gordura (Melinis minutiflora) Capim–Marandu (Brachiaria brizantha), Setaria (Setaria anceps) Capim-Humidicula (Brachiaria humidicula) and Andropogon (Andropogon gayanus). The collection of samples and procedures were developed at the Institute of Animal Science, Nova Odessa, Brazil. The grasses came from isolated paddocks. Three subsamples were used: 1-control sample (AC1); 2-control frozen sample (ACC2); 3-infested sample (AI). AC1, after the process of larvae recoveries, served as control, the rest was frozen. After de-freezing, it was divided into two samples (ACC2 and AI). In ACC2, no larvae were observed. AI was infested with 1600 ± 30 L3 larvae of trichostrongylids, recovered from sheep manure. The larvae recovery procedures were applied to the samples in the three periods. The overall mean of recovery (±SD) and percentage of success was estimated (SISVAR®) in 1544.63 ± 1.31 larvae, 96.54 ± 17% respectively. There were no differences between grass genera, as well as between weeks, with near recovery numbers (p&gt;0.05). The technique had satisfactory results in a short time.

The identification of small molecule inhibitors with anthelmintic activities that target conserved proteins among ruminant gastrointestinal nematodes.

Gastrointestinal nematode (GIN) infections are a major concern for the ruminant industry worldwide and result in significant production losses. Naturally occurring polyparasitism and increasing drug resistance that potentiate disease outcomes are observed among the most prevalent GINs of veterinary importance. Within the five major taxonomic clades, clade Va represents a group of GINs that predominantly affect the abomasum or small intestine of ruminants. However, the development of effective broad-spectrum anthelmintics against ruminant clade Va GINs has been challenged by a lack of comprehensive druggable genome resources. Here, we first assembled draft genomes for three clade Va species (Cooperia oncophora, Trichostrongylus colubriformis, and Ostertagia ostertagi) and compared them with closely related ruminant GINs. Genome-wide phylogenetic reconstruction showed a relationship among ruminant GINs structured by taxonomic classification. Orthogroup (OG) inference and functional enrichment analyses identified 220 clade Va-specific and Va-conserved OGs, enriched for functions related to cell cycle and cellular senescence. Further transcriptomic analysis identified 61 taxonomically and functionally conserved clade Va OGs that may function as drug targets for new broad-spectrum anthelmintics. Chemogenomic screening identified 11 compounds targeting homologs of these OGs, thus having potential anthelmintic activity. In in vitro phenotypic assays, three kinase inhibitors (digitoxigenin, K-252a, and staurosporine) exhibited broad-spectrum anthelmintic activities against clade Va GINs by obstructing the motility of exsheathed L3 (xL3) or molting of xL3 to L4. These results demonstrate valuable applications of the new ruminant GIN genomes in gaining better insights into their life cycles and offer a contemporary approach to discovering the next generation of anthelmintics.IMPORTANCEGastrointestinal nematode (GIN) infections in ruminants are caused by parasites that inhibit normal function in the digestive tract of cattle, sheep, and goats, thereby causing morbidity and mortality. Coinfection and increasing drug resistance to current therapeutic agents will continue to worsen disease outcomes and impose significant production losses on domestic livestock producers worldwide. In combination with ongoing therapeutic efforts, advancing the discovery of new drugs with novel modes of action is critical for better controlling GIN infections. The significance of this study is in assembling and characterizing new GIN genomes of Cooperia oncophora, Ostertagia ostertagi, and Trichostrongylus colubriformis for facilitating a multi-omics approach to identify novel, biologically conserved drug targets for five major GINs of veterinary importance. With this information, we were then able to demonstrate the potential of commercially available compounds as new anthelmintics.

Genetic Parameter Estimation and Selection for Resistance to Gastrointestinal Nematode Parasites in Sheep-A Review.

Gastrointestinal nematodes (GINs) are a major problem affecting sheep production systems worldwide. The flocks infected with GINs can undergo significant economic losses due to a decrease in productivity, the animals' deaths, and the costs associated with treatments. The over-reliance on anthelmintics in the past years to eliminate GINs has resulted in the development of resistance against the available commercial anthelmintics. Genetically resistant animals can be used in mating systems to improve the overall flock resistance. This review aimed to summarize the estimated genetic parameters for resistance traits and genetic gains through the use of genetic/genomic selection for resistance to GINs in sheep. Heritability estimates from the literature ranged from 0.00 to 0.46 for fecal egg counts, 0.12 to 0.37 for packed cell volume/hematocrit, 0.07 to 0.26 for FAffa MAlan CHArt (FAMACHA©), from 0.10 to 0.37 for blood parameters, and 0.19 for Immunoglobulin A. Genetic correlations between traits measuring resistance to GINs and production traits ranged from negative to positive values in the literature. Genetic gains are possible when genetic/genomic selection for GIN resistance is applied. Therefore, genetic/genomic selection can be used to improve flocks' resistance to GINs as a sustainable approach in sheep production systems.

Innovative use of sensor technology to study grazing behaviour and its associations with parasitic resistance in sheep

Gastrointestinal nematodes (GINs) are a concern for sheep production and are associated with significant economic losses globally, driving the need for effective management strategies. The aims of this research were first to determine the influence of GIN infections on sheep grazing behaviours, specifically grazing time (GT) and grazing event length (GL), and then to estimate the genetic and phenotypic correlation between faecal egg counts (FEC) and salivary specific IgA activity vs GT and GL. Data were collected from 146 Merino sheep on a commercial farm in Victoria, Australia. Faecal, saliva and body weight (BW) were collected at four time points (A: Oct 2019, B: early May 2020, C: late May 2020, and D: Jul 2020), while tri-axial accelerometer sensors recorded GT and GL for the length of 26 days between B and C. Univariate linear regression and Bayesian Generalised Linear Mixed Model, estimated using Markov Chain Monte Carlo, were used to assess the relationships between the behaviours and infection indicators. We found an increase in the logarithm of FEC was associated with a significant rise in grazing time (p < 0.05), suggesting compensatory behaviour in infected sheep. GT also accounted for 6% of the FEC variation. In contrast, the effect of IgA on GT was not significant (p > 0.05). There was a positive genetic and phenotypic correlation estimated between GT and FEC, however, the High Posterior Density interval for the genetic and phenotypic correlations between GT and FEC indicates some uncertainty in these estimates. These results imply that sheep may modify their grazing strategies as an adaptive response to parasitic infections to ease the impact on their nutritional intake. This study improves our understanding of how natural GIN infections affect sheep behaviour and highlights the potential to use animal behaviours as a precision livestock farming tool and in breeding for resilience against parasites.

Investigating the perceived versus actual gastrointestinal nematode challenge on extensive sheep farms

Extensive farming systems form an integral part of sheep production systems across Europe. However, with innate production handicaps, declining sheep numbers and narrow economic margins, production is becoming increasingly challenging threatening the future sustainability of the industry. Gastrointestinal nematodes (GINs) are a significant cause of production losses to the global sheep industry, with well-established resistance to the major anthelmintic groups. Traditionally, extensive farming systems are not thought to have a significant parasite challenge compared with intensive farms, but there is a need to identify the scale and importance of GINs on extensive farms to inform the need for sustainable control strategies. In this study, a questionnaire of extensive farmers (n=34) was conducted and parasitological data were collected from nine study farms to investigate the perceived versus actual GIN and anthelmintic resistance challenge faced by extensive farms. The results showed a production-limiting challenge on most farms, with a higher GIN challenge observed on improved pastures. Furthermore, over half of the extensive farmers perceived anthelmintic resistance to be a greater problem for intensive farmers, with only 20% of respondents reporting known anthelmintic resistance. However, all study farms had evidence of resistance to at least one group of anthelmintics. Consequently, this study has demonstrated that despite the traditional perception of parasitism on extensive farms, there is a need to increasingly consider its impact and take a proactive approach to sustainable control, with solutions tailored to their unique management.