Local immune response of Canarian Majorera goats infected with Teladorsagia circumcincta

Background Due to increased anthelmintic resistance, alternative methods to drugs are necessary to control gastrointestinal nematodes (GINs). Some of the most promising alternatives are based on the immune response of the host, such as the selection of genetically resistant breeds or the use of vaccines against these parasites. Given the limited information available on the immune response against GINs in goats, this study investigated the local immune response of goat kids of an indigenous Canary Islands breed (Majorera breed) experimentally infected with Teladorsagia circumcincta, one of the most pathogenic and prevalent GIN species. Methods For this purpose, the relationship between different parasitological (number of mature and immature worms, worm length, and number of intrauterine eggs) and immunological parameters at the local level (related to both the humoral and cellular immune response) was analyzed at early (1 week post-infection [wpi]) and late (8 wpi) stages of infection. Results Primary infection of goat kids with T. circumcincta infective larvae (L3) generated a complex immune response that could be defined as Th2 type, characterized by increased infiltration in abomasal tissues of several effector cells as well as a progressive presence of specific antibodies against parasitic antigens in the gastric mucus. Cellular responses were evidenced from 1 wpi onward, showing an increase in antigen-presenting cells and various lymphocyte subsets in the gastric mucosa. Conclusions The complexity of the host response was evidenced by statistically significant changes in the number of all these subpopulations (MHCII+, CD4+, CD8+, γδ+, CD45R+, IgA+, and IgG+), as well as in the evolution of the relative cytokine gene expression. From a functional point of view, negative associations were observed between the number of most of the immune cells (CD4, IgA, IgG, and CD45R cells) and parameters that could be related to the fecundity of worms, a phenomenon that was especially evident when the number of IgG and CD45R cells or the specific IgA levels of the gastric mucus were compared with parasitological parameters such as the female worm length or fecal egg counts at 8 wpi. Graphical Abstract

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.

Detection of anthelmintic resistance in nematodes infecting dairy heifers in Puerto Rico

The efficacy of the anthelmintic albendazole (ALB), doramectin (DOR) and ivermectin (IVM) were evaluated in Holstein and Holstein crossbreed dairy heifers using the fecal egg count reduction test (FECRT). Dairy heifers (n=420; ~6 months of age; BW = 149 ± 39.6 kg) were evaluated in 21 dairy farms. All heifers were required to be on pasture and not have been exposed to anthelmintic treatment for a minimum of 3 months. At each dairy farm, a priori, groups of at least 18 heifers were randomly divided to be treated with IVM, or DOR, or ALB following manufacturer's instructions. Fecal samples were collected directly from the rectum 7 days before anthelmintic treatment (d-7), at the time of the treatment (d0), and 14 days after treatment (d14). Only heifers that had an average FEC ³ 100 eggs per gram of feces (average of FEC from day d-7 and d0) were considered in the FECRT. The FECRT was determined by the modified McMaster technique. Of the three-anthelmintic used, ALB (n=142) proved to be the most effective (P < 0.0005) with an efficacy of 67.47% ± 8.43. The efficacy of DOR and IVM did not differ (P = 0.8713). While DOR (n = 130) exhibited a efficacy of 25.50% ± 18.00, IVM (n = 148) exhibited a efficacy of -8.13% ± 19.89 due to an increase in FEC after treatment. Dairy farmers should implement integrated methods of nematode control to preserve the effectiveness of currently available anthelmintics.

Nanoparticles as Alternatives for the Control of Haemonchus contortus: A Systematic Approach to Unveil New Anti-haemonchiasis Agents

Haemonchus contortus is an infectious gastrointestinal nematode parasite of small ruminants. This study addresses the in vitro/in vivo anti-haemonchiasis potential, toxicological effects, and mechanism of action of nanoparticles. Online databases were used to search and retrieve the published literature (2000 to 2021). A total of 18 articles were selected and reviewed, out of which, 13 (72.2%) studies reported in vitro, 9 (50.0%) in vivo, and 4 (22.2%) both in vitro/in vivo efficacy of different nanoparticles. Mostly, organic nanoparticles (77.7%) were used including polymeric (85.7%) and lipid nanoparticles (14.3%). The highest efficacy, in vitro, of 100% resulted from using encapsulated bromelain against eggs, larvae, and adult worm mortality at 4, 2, and 1 mg/ml, respectively. While in vivo, encapsulated Eucalyptus staigeriana oil reduced worm burden by 83.75% and encapsulated Cymbopogon citratus nano-emulsion by 83.1%. Encapsulated bromelain, encapsulated Eucalyptus staigeriana oil, and encapsulated Cymbopogon citratus nano-emulsion were safe and non-toxic in vivo. Encapsulated bromelain damaged the cuticle, caused paralysis, and death. Nanoparticles could be a potential source for developing novel anthelmintic drugs to overcome the emerging issue of anthelmintic resistance in H. contortus. Studies on molecular effects, toxicological consequences, and different pharmacological targets of nanoparticles are required in future research.

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

Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses

Background Cyathostomins are the most important and common parasitic nematodes of horses, with > 50 species known to occur worldwide. The frequent and indiscriminate use of anthelmintics has resulted in the development of anthelmintic resistance (AR) in horse nematodes. In this study we assessed the efficacy of commonly used anthelmintics against cyathostomins in Australian thoroughbred horses. Methods Two drug efficacy trials per farm were conducted on two thoroughbred horse farms in the state of Victoria, Australia. In the first trial, the horses on Farm A were treated with single and combinations of anthelmintics, including oxfendazole (OFZ), abamectin (ABM), abamectin and morantel (ABM + MOR), moxidectin (MOX) and oxfendazole and pyrantel (OFZ + PYR), at the recommended doses, whereas the horses on Farm B only received MOX, at the recommended dose. The faecal egg count reduction test (FECRT) was used to determine the efficacy and egg reappearance period (ERP) of anthelmintics. Based on the results of the first trial, the efficacies of MOX and a combination of ABM + MOR were reassessed to confirm their activities against cyathostomins. Results Of the five anthelmintic products tested on Farm A, resistance against OFZ, ABM and OFZ + PYR was found, with efficacies of − 41% (− 195% lower confidence limit [LCL]), 73% (60% LCL) and 82% (66% LCL) at 2 weeks post-treatment, respectively. The FECRT showed high efficacies of MOX and ABM + MOR (100%) at 2 week post-treatment and shortened ERPs for these anthelmintics (ABM + MOR: 4 weeks; MOX: 5 weeks). Resistance to MOX was found on Farm B, with a reduced efficacy of 90% (70% LCL) and 89% (82% LCL) at 2 weeks post-treatment in trials one and two, respectively. Conclusions This study provides the first evidence of MOX- and multidrug-resistant (ABM and combinations of anthelmintics) cyathostomins in Australia and indicates the need for continuous surveillance of the efficacy of currently effective anthelmintics and large-scale investigations to assess the ERP for various anthelmintics. Graphical Abstract

Anthelmintic Potential of Medicinal Plants against Ancylostoma caninum

Ancylostoma caninum is one of the most important hookworms in dogs. A study revealed that the prevalence of ancylostomiasis in Indonesia is relatively high. However, cases of persistent ancylostomiasis in dogs were reported, indicating the possibility of anthelmintic resistance. The aim of this review is to provide an overview of the anthelmintic potential of plants preclinically against A. caninum based on related research articles. This review retrieved 14 articles from 2001 to 2021 investigating 19 different plants. Momordica charantia, Diospyros anisandra, and Citrus aurantiifolia hold a promising prospect as anthelmintic against A. caninum. This review found aspects of those medicinal plants that need to be investigated deeper to improve our understanding of the matter. In vitro results in this review have not yet been tested in in vivo trials, which are essential in determining the efficacy and safety of the use of these medicinal plants and also to justify its clinical application.

Genomic landscape of drug response reveals novel mediators of anthelmintic resistance

Understanding the genetic basis of anthelmintic drug resistance in parasitic nematodes is key to tracking and combatting their spread. Here, we use a genetic cross in a natural host-parasite system to simultaneously map resistance loci for the three major classes of anthelmintics. This approach identifies novel alleles for resistance to benzimidazoles and levamisole and implicates the transcription factor, cky-1, in ivermectin resistance. This gene is within a locus under selection in ivermectin resistant populations worldwide; functional validation using knockout and gene expression experiments supports a role for cky-1 overexpression in ivermectin resistance. Our work demonstrates the feasibility of high-resolution forward genetics in a parasitic nematode, and identifies variants for the development of molecular diagnostics to combat drug resistance in the field.

Effect of levamisole on gastrointestinal nematodes and weight gain of grazing livestock in the municipality of San Jose Chiltepec, Oaxaca, Mexico

The aim of the present work was to study the effect of administration of levamisole on parasitic load of gastrointestinal nematodes (GIN) and the percentage of weight gain of grazing cattle. The animals were randomly distributed to form three experimental groups, levamisole, ivermectin and control. The collection of feces samples was carried out one day before and 15 days’ post-treatment and subsequently it was quantifying the eggs number per gram of feces. The body weight of the animals was recorded at days 0, 15, 30 and 45 after treatments to evaluate its gain. The results observed up to the final day (45 days’ post-treatment) showed the group treated with Ivermectin had a 10.1% increase in body weight, while the group under Levamisole treatment had an increase of 14.3%. The groups under ivermectin and levamisole showed a decrease in the number of eggs per grams of feces (EPG), which were measured 15 days after their treatment (22.5 EPG in ivermectin) and (55.0 EPG in levamisole) compared to the vehicle group (377.5 EPG) and pre-treatment (486.5 EPG). In the present work, it was possible to show that with two subcutaneous administrations of levamisole in grazing calves in the municipality of Chiltepec, Oaxaca, it’s possible to increase the weight in cattle while decreasing its parasite load of GIN. However, it is necessary to determine the anthelmintic resistance in farms that report the use of levamisole with different treatment and repeated doses of levamisole.