Biomarkers of gastrointestinal nematodes in beef cattle raised in a tropical area.

Biomarkers are specific molecular, histological, or physiological characteristics of normal or pathogenic biological processes and are promising in the diagnosis of gastrointestinal nematodes (GINs). Although some biomarkers have been validated for infection by Ostertagia sp. in cattle raised in temperate regions, there is a lack of information for tropical regions. The aim of this project was to assess potential biomarkers and validate the most promising. In the first study, 36 bovines (Nelore breed) naturally infected by GINs were distributed into two groups: infected (not treated with anthelmintic) and treated (treated with fenbendazole on days 0, 7, 14, 21, 28, 42, and 56). The variables of interest were live weight, fecal egg count, hemogram, serum biochemical markers, phosphorus, gastrin, and pepsinogen. In the second step, pepsinogen was assessed in cattle of the Nelore breed distributed among three groups: infected (not treated with anthelmintic), MOX (treated with moxidectin), and IVM + BZD (treated with ivermectin + albendazole). In the first study, no difference between groups was found for weight, albumin, hematocrit (corpuscular volume [CV]), erythrocytes, or hemoglobin. Negative correlations were found between pepsinogen and both CV and albumin, and albumin was negatively correlated with the percentage of Haemonchus sp. in the fecal culture. Among the biomarkers, only pepsinogen differentiated treated and infected (beginning with the 28th day of the study). In the second study, a reduction in pepsinogen was found after anthelmintic treatment. Therefore, pepsinogen is a promising biomarker of worms in cattle naturally infected by the genera Haemonchus and Cooperia in tropical areas.

Corrigendum: A revision of the trichostrongylid nematode Cooperia Ransom, 1907, from deer game: recent integrative research confirms the existence of the ancient host-specific species Cooperia ventricosa (Rudolphi, 1809).

[This corrects the article DOI: 10.3389/fvets.2024.1346417.].

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.

A revision of the trichostrongylid nematode Cooperia Ransom, 1907, from deer game: recent integrative research confirms the existence of the ancient host-specific species Cooperia ventricosa (Rudolphi, 1809).

The trichostrongylid roundworms of the genus Cooperia, which are important in veterinary medicine, currently comprise 19 valid species that parasitize the small intestine of both free-living and domestic ruminants. Only four Cooperia spp. have been reported in Europe, namely C. oncophora, C. punctata, C. curticei and C. pectinata. In 2018-2022, 25 red deer (Cervus elaphus) and 30 sika deer (Cervus nippon) of both sexes and various ages from several remote locations in the Czech Republic were parasitologically examined. Intestinal nematodes of the genus Cooperia were found only in two northern regions. Using the globally recognized key book on trichostrongylid nematodes, they were preliminarily identified as C. pectinata. However, a molecular analysis of cox2 and ITS rDNA gene sequences revealed that Cooperia sp. parasitizing Czech deer is a separate taxon that is more closely related to C. oncophora than to C. pectinata. A subsequent morphological analysis and literature survey confirmed the independence of deer Cooperia sp., which is similar but not identical to bovid C. pectinata. Previous long-term correct identifications of bovid C. pectinata and misidentifications of deer Cooperia species were caused by a fundamental error in the key book mentioned above. Interestingly, the ancient trichostrongylid nematode Strongylus ventricosus from the type host red deer (Cervus elaphus) shot near Greifswald (Germany) was described by Rudolphi in 1809. Rudolphi's type material (one male and four females) was deposited in the Museum für Naturkunde (Berlin). Later, the ancient species S. ventricosus was taken as a synonym for various Cooperia spp. Our current re-examination of the type male indicated that there is a relatively good agreement with our new material from Czech deer regarding the most important characteristics of S. ventricosus (i.e., the shape and size of the male spicules); however, Rudolphi's type material is in rather poor condition. The suggested resurrection of the deer Cooperia sp. in this study as Cooperia ventricosa (Rudolphi, 1809) requires verification by collecting and analyzing new nematode material from the type locality near Greifswald.

Toltrazuril + fenbendazole for cattle: Pharmacokinetics and efficacy against Eimeria spp. and gastrointestinal nematodes.

The present work evaluated the pharmacokinetics and efficacy of the association of 15cmg/kg toltrazuril +5cmg/kg fenbendazole against Eimeria spp. and gastrointestinal nematodes (GINs) in calves of different regions of Brazil (Center-West, Southeast, and South). A total of seven experiments were carried out, five of which determined formulation efficacy against Eimeria spp., considering the following aspects: therapeutic, preventive, metaphylactic, and residual efficacy. Therapeutic efficacy experiments for GINs were carried out by parasitological necropsy. The toltrazuril + fenbendazole association demonstrated ≥95% efficacy against Eimeria spp. for 21 days post-treatment (DPT). When used preventively and metaphylatically, the same association demonstrated ≥97% efficacy against E. zuernii, E. ellipsoidalis, E. cylindrica, E. bovis, E. wyomingensis and E. auburnensis. Toltrazuril + fenbendazole administered seven days before challenge was 100% effective against all these Eimeria species. Results of therapeutic, preventive, metaphylactic and residual efficacies can be related to the pharmacokinetic results, especially considering toltrazuril sulfone, which was detected in animal plasma for a longer period than the parent compound. Toltrazuril + fenbendazole achieved 100% anthelminthic efficacy against the GINs Haemonchus placei (L4), Cooperia pectinata and Oesophagostomum radiatum; 99.94% against adult H. placei; and 99.98% against C. puntacta. The association of toltrazuril + fenbendazole, associated with other measures, is an important and suitable tool for the control and treatment of Eimeria spp. and GINs in young cattle.

Simultaneous resistance to multiple anthelmintic classes in nematode parasites of cattle in New Zealand.

Resistance to the benzimidazole and macrocyclic lactone anthelmintics is widespread in Cooperia spp. on cattle farms in New Zealand. Since this was first documented in 2006 little has changed in cattle farming systems except for the widespread use of levamisole to control Cooperia spp. in young cattle (i.e., parasite control has maintained an almost total reliance on use of anthelmintics). Here we report the emergence of simultaneous resistance to the benzimidazole, macrocyclic lactone and levamisole anthelmintics in Cooperia spp. and in Ostertagia spp. Anthelmintic efficacy against nematode parasites of cattle was investigated on four commercial farms following reports of poor animal growth rates and welfare, and positive faecal egg counts, despite routine treatment with combination anthelmintics, which included levamisole. Faecal egg count reduction tests involved 15 animals per treatment group, individual egg counts (paired samples) conducted pre- and post-treatment, with eggs counted to ≤ 15 eggs per g faeces and larval cultures for morphological identification. Actives tested varied between farms but always included levamisole alone and several combination products containing levamisole. Of the 20 tests conducted (i.e., 5 products on each of 4 farms) only 3 exceeded 90% efficacy against Cooperia spp. even though 8 of the products tested were combinations containing levamisole and at least one other broad-spectrum anthelmintic. Levamisole used alone achieved efficacies between 44% and 71% against Cooperia spp. across the four trials. The only product to exceed 95% efficacy against Cooperia spp. was a combination of monepantel + abamectin which was 100% effective against all parasites. Resistance to oxfendazole in Ostertagia spp. was indicated on 3 farms, while on one farm efficacy of all the tested products was ≤75% against this parasite. All the farms involved in this study were farming intensive cattle operations with an almost total reliance on anthelmintics to control parasitism. The results clearly demonstrate the emergence of simultaneous resistance to oxfendazole, levamisole and the macrocyclic lactone anthelmintics. Despite years of advice and recommendations to change farming practices away from intensive monocultures, many farmers have continued with the practice, and some are now faced with the very real possibility of being unable to control cattle parasites on their farms.

Efficacy of a fixed-dose combination injectable (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) in Australian cattle against naturally acquired gastrointestinal nematode infections.

Australian producers have long used macrocyclic lactones (MLs) to successfully control cattle gastrointestinal nematodes (GINs) and consequently improve production parameters. However, the trajectory of ML resistance development in cattle GINs is following that of small ruminant nematode populations, highlighting a need for novel treatment options to provide efficacy in the current environment and interrupt the long-term establishment of ML-resistant GIN populations in Australian cattle. Here, we describe three field studies conducted in Australia to evaluate the efficacy of a single administration of a novel fixed-dose combination injectable (FDCI) endectocide against naturally acquired infections of cattle GINs. The FDCI is administered subcutaneously to deliver 0.2 mg/kg doramectin and 6 mg/kg levamisole hydrochloride (HCl). Study sites consisted of three farms in New South Wales (n = 2) and Victoria (n = 1). At each site, cattle were randomly allocated into one of three treatment groups: (1) untreated control (saline), (2) FDCI (0.2 mg/kg doramectin, 6 mg/kg levamisole HCl) or (3) positive control (0.2 mg/kg ivermectin). All treatments were administered on Day 0. Fecal samples were collected prior to treatment on Days -1 (Study 3) or 0 (Studies 1 and 2) and again on Day 14 (post-treatment) to evaluate efficacy via fecal egg count (FEC) and for coproculture. Adequacy of infection was confirmed at all three study sites, with Day 14 geometric mean (GM) FECs for saline-treated cattle ranging from 32.5 eggs per gram (EPG) to 623.7 EPG. FECs for FDCI-treated cattle were significantly reduced compared to saline-treated cattle (p ≤ 0.0001) on Day 14, with GM-based efficacy ≥ 99.7% at all three study sites. In contrast, ivermectin was 97.4% effective against cattle GINs in Study 1 but was only 47.2% and 39.8% effective at study site 2 and 3, respectively. Genus-specific efficacies suggest the presence of ivermectin-resistant Cooperia spp. (Study 1), Haemonchus spp. (Study 2) and Ostertagia spp. (Study 3) populations in the naturally infected cattle used in these studies. The post-treatment FEC and genus-specific efficacy estimations indicate the doramectin + levamisole HCl FDCI was highly efficacious against cattle GINs even in the face of ivermectin LOE at study sites 2 and 3. The efficacy of the new FDCI against both ML-susceptible and ML-resistant economically important cattle GINs in Australia affirms it is a valuable treatment option for producers operating in an environment of ML loss of efficacy.

Benzimidazole Resistance in Cattle: The First Report of the Presence of F200Y Mutation in Cooperia in Ecuador.

Anthelmintic resistance among GINs in cattle is a worldwide issue. Identifying the early signs of anthelmintic resistance (AR) is necessary to sustainably manage bovine parasitic infections. This study aimed to evaluate the resistance status of bovine parasitic nematodes against FBZ on a farm with a known history of broad-spectrum anthelmintic usage in Ecuador. FBZ efficacy was analyzed using a fecal egg count reduction test (FECR test) and ß-tubulin 1 mutation identification in Cooperia spp., the dominant nematode parasite identified before and after treatment. According to the FECR test, the nematode population was susceptible to FBZ. After amplifying and cloning the ß-tubulin 1 of Cooperia spp., an F200Y mutation was found in 43% of the pooled larva coproculture after treatment. This study reports, for the first time, the presence of F200Y resistance-conferring mutation in Cooperia spp. in Ecuador. Although the nematode population was phenotypically susceptible to FBZ, the presence of F200Y suggests the existence of resistance in the early stages. Our findings highlight the need to implement alternative control strategies for parasitic infections besides broad-spectrum anthelmintics.

Integration of ITS-2 rDNA nemabiome metabarcoding with Fecal Egg Count Reduction Testing (FECRT) reveals ivermectin resistance in multiple gastrointestinal nematode species, including hypobiotic Ostertagia ostertagi, in western Canadian beef cattle.

A large-scale Fecal Egg Count Reduction Test (FECRT) was integrated with ITS-2 rDNA nemabiome metabarcoding to investigate anthelmintic resistance in gastrointestinal nematode (GIN) parasites in western Canadian beef cattle. The study was designed to detect anthelmintic resistance with the low fecal egg counts that typically occur in cattle in northern temperate regions. Two hundred and thirty-four auction market-derived, fall-weaned steer calves coming off pasture were randomized into three groups in feedlot pens: an untreated control group, an injectable ivermectin treatment group, and an injectable ivermectin/oral fenbendazole combination treatment group. Each group was divided into six replicate pens with 13 calves per pen. Individual fecal samples were taken pre-treatment, day 14 post-treatment, and at monthly intervals for six months for strongyle egg counting and metabarcoding. Ivermectin treatment resulted in an 82.4% mean strongyle-type fecal egg count reduction (95% CI 67.8-90.4) at 14 days post-treatment, while the combination treatment was 100% effective, confirming the existence of ivermectin-resistant GIN. Nemabiome metabarcoding of third-stage larvae from coprocultures revealed an increase in the relative abundance of Cooperia oncophora, Cooperia punctata, and Haemonchus placei at 14 days post-ivermectin treatment indicating ivermectin resistance in adult worms. In contrast, Ostertagia ostertagi third-stage larvae were almost completely absent from day 14 coprocultures, indicating that adult worms of this species were not ivermectin resistant. However, there was a recrudescence of O. ostertagi third stage larvae in coprocultures at three to six months post-ivermectin treatment, which indicated ivermectin resistance in hypobiotic larvae. The calves were recruited from the auction market and, therefore, derived from multiple sources in western Canada, suggesting that ivermectin-resistant parasites, including hypobiotic O. ostertagi larvae, are likely widespread in western Canadian beef herds. This work demonstrates the value of integrating ITS-2 rDNA metabarcoding with the FECRT to enhance anthelmintic resistance detection and provide GIN species- and stage-specific information.

Novel epidemiological model of gastrointestinal nematode infection to assess grazing cattle resilience by integrating host growth, parasite, grass and environmental dynamics.

Gastrointestinal nematode (GIN) infections are ubiquitous and often cause morbidity and reduced performance in livestock. Emerging anthelmintic resistance and increasing change in climate patterns require evaluation of alternatives to traditional treatment and management practices. Mathematical models of parasite transmission between hosts and the environment have contributed towards the design of appropriate control strategies in ruminants, but have yet to account for relationships between climate, infection pressure, immunity, resources, and growth. Here, we develop a new epidemiological model of GIN transmission in a herd of grazing cattle, including host tolerance (body weight and feed intake), parasite burden and acquisition of immunity, together with weather-dependent development of parasite free-living stages, and the influence of grass availability on parasite transmission. Dynamic host, parasite and environmental factors drive a variable rate of transmission. Using literature sources, the model was parametrised for Ostertagia ostertagi, the prevailing pathogenic GIN in grazing cattle populations in temperate climates. Model outputs were validated on published empirical studies from first season grazing cattle in northern Europe. These results show satisfactory qualitative and quantitative performance of the model; they also indicate the model may approximate the dynamics of grazing systems under co-infection by O. ostertagi and Cooperia oncophora, a second GIN species common in cattle. In addition, model behaviour was explored under illustrative anthelmintic treatment strategies, considering impacts on parasitological and performance variables. The model has potential for extension to explore altered infection dynamics as a result of management and climate change, and to optimise treatment strategies accordingly. As the first known mechanistic model to combine parasitic and free-living stages of GIN with host feed-intake and growth, it is well suited to predict complex system responses under non-stationary conditions. We discuss the implications, limitations and extensions of the model, and its potential to assist in the development of sustainable parasite control strategies.

Tracking gastrointestinal nematode risk on cattle farms through pasture contamination mapping.

Gastrointestinal nematode (GIN) parasites in grazing cattle are a major cause of production loss and their control is increasingly difficult due to anthelmintic resistance and climate change. Rotational grazing can support control and decrease reliance on chemical intervention, but is often complex due to the need to track grazing periods and infection levels, and the effect of weather on larval availability. In this paper, a simulation model was developed to predict the availability of infective larvae of the bovine GIN, Ostertagia ostertagi, at the level of individual pastures. The model was applied within a complex rotational grazing system and successfully reproduced observed variation in larval density between fields and over time. Four groups of cattle in their second grazing season (n = 44) were followed throughout the temperate grazing season with regular assessment of GIN faecal egg counts, which were dominated by O. ostertagi, animal weight and recording of field rotations. Each group of cattle was rotationally grazed on six group-specific fields throughout the 2019 grazing season. Maps and calendars were produced to illustrate the change in pasture infectivity (density of L3 on herbage) across the 24 separate grazing fields. Simulations predicted differences in pasture contamination levels in relation to the timing of grazing and the return period. A proportion of L3 was predicted to persist on herbage over winter, declining to similar intensities across fields before the start of the following grazing season, irrespective of contamination levels in the previous year. Model predictions showed good agreement with pasture larval counts. The model also simulated differences in seasonal pasture infectivity under rotational grazing in systems that differed in temperature and rainfall profiles. Further application could support individual farm decisions on evasive grazing and refugia management, and improved regional evaluation of optimal grazing strategies for parasite control. The integration of weather and livestock movement is inherent to the model, and facilitates consideration of climate change adaptation through improved disease control.

Regional heterogeneity and unexpectedly high abundance of Cooperia punctata in beef cattle at a northern latitude revealed by ITS-2 rDNA nemabiome metabarcoding.

BACKGROUND: The species composition of cattle gastrointestinal nematode (GIN) communities can vary greatly between regions. Despite this, there is remarkably little large-scale surveillance data for cattle GIN species which is due, at least in part, to a lack of scalable diagnostic tools. This lack of regional GIN species-level data represents a major knowledge gap for evidence-based parasite management and assessing the status and impact of factors such as climate change and anthelmintic drug resistance. METHODS: This paper presents a large-scale survey of GIN in beef herds across western Canada using ITS-2 rDNA nemabiome metabarcoding. Individual fecal samples were collected from 6 to 20 randomly selected heifers (n = 1665) from each of 85 herds between September 2016 and February 2017 and 10-25 first season calves (n = 824) from each of 42 herds between November 2016 and February 2017. RESULTS: Gastrointestinal nematode communities in heifers and calves were similar in Alberta and Saskatchewan, with Ostertagia ostertagi and Cooperia oncophora being the predominant GIN species in all herds consistent with previous studies. However, in Manitoba, Cooperia punctata was the predominant species overall and the most abundant GIN species in calves from 4/8 beef herds. CONCLUSIONS: This study revealed a marked regional heterogeneity of GIN species in grazing beef herds in western Canada. The predominance of C. punctata in Manitoba is unexpected, as although this parasite is often the predominant cattle GIN species in more southerly latitudes, it is generally only a minor component of cattle GIN communities in northern temperate regions. We hypothesize that the unexpected predominance of C. punctata at such a northerly latitude represents a range expansion, likely associated with changes in climate, anthelmintic use, management, and/or animal movement. Whatever the cause, these results are of practical concern since C. punctata is more pathogenic than C. oncophora, the Cooperia species that typically predominates in cooler temperate regions. Finally, this study illustrates the value of ITS-2 rDNA nemabiome metabarcoding as a surveillance tool for ruminant GIN parasites.

Effect of antihelminths with contrasting efficacy against gastrointestinal nematodes on the live-weight gain of young Nellore cattle.

We estimated the losses caused by gastrointestinal nematode (GIN) infections in young Nellore cattle born in three consecutive calving seasons (Cycles I, II and III). Three groups of animals: Group 1 - free from GIN using 2.5 mg/kg of albendazole sulfoxide; Group II - free from Oesophagosomum radiatum using 0.2 mg/kg of ivermectin but infected with ivermectin-resistant Haemonchus placei and Cooperia spp.; and Group III - non-treated experimental control animals, infected with all GIN, were observed over a period of 12 months. Male and female calves were evaluated starting before weaning when the animals were an average of approximately four months of age. In Cycle I, only females were evaluated. All the animals continued to graze on pastures of Urochloa spp. (= Brachiaria). All the groups showed median faecal egg counts of fewer than 250 eggs per gram (EPG), and no clinical signs of parasitic gastroenteritis were observed. The blood variables were within the normal ranges, and no calf presented anaemia. In most of the samplings, the median EPGs were significantly lower (P < 0.05) in the group treated with albendazole. Throughout the experiment, the most prevalent parasite observed in the control group was Cooperia spp., followed in decreasing order by Haemonchus spp., O. radiatum and Trichostrongylus spp. All the groups of calves exhibited weight gain throughout the trials with control group displaying the lowest body weight gain. Body weight variables between the albendazole- and ivermectin-treated groups were not significantly different (P > 0.05). After weaning, females animals in albendazole and ivermectin treated groups exhibited higher body weights, 20.4% and 22.7%, respectively, than those of the control group. Likewise, males treated with albendazole and ivermectin exhibited 27.6% and 25.8%, respectively, more body weight gain than animals under control group. Because the main difference between the ivermectin and the control groups was the O. radiatum parasitism, most of the losses in the control group were possibly due to this nematode species. Nevertheless, the other nematodes species that occurred in relatively high intensities in control group could also have an additive effect in such losses.

Prevalence of trichostrongylus in sheep in the district Zhob, Balochistan, Pakistan / [Prevalência de trichostrongylus em ovelhas no distrito Zhob, Balochistão, Paquistão]

Trichostrongylid em ovelhas foi estudado no Distrito Zhob, Balochistan. Foram coletados 120 tratos gastrointestinais (GIT) de ovelhas do matadouro do distrito. Estas amostras foram processadas para isolamento e identificação de nematódeos tricostrônquicos no Laboratório do Hospital Veterinário do Distrito Zhob. A taxa de prevalência geral foi de 39,1% em machos e 60,8% em fêmeas (p=0,001). A taxa de prevalência em duas raças viz Balochi e Rakhshani foi de 58,3% e 41,6%, respectivamente (p=0,01). A prevalência da espécie observada com Trichostrongylus foi 19,1%, Haemonchus foi 20,8%, Cooperia foi 29,1% e Nematodirus foi 30,8% (p=0,087). Quanto a quantidade de espécies infestadas pelas ovelhas, um único tipo de parasita estava em 32,5% de animais, dois tipos de espécies parasitárias em 36,3% dos animais e três tipos de espécies parasitárias em 30,8% dos animais (p=0,366).(AU)

Primer registro de Cooperia curticei (Strongylida: Trichostrongylidae) en un ovino de la región del noroeste argentino / First report of Cooperia curticei (Strongylida: Trichostrongylidae) in sheep from northwestern Argentina

Resumen Cooperia curticei, es un nematodo afín a los ovinos que se aloja en el intestino delgado de estos. Su presencia en Argentina ha sido registrada en ambientes como la región semiárida en la Pampa, subhúmeda pampeana en Buenos Aires y en la región subtropical en Corrientes. El objetivo de este trabajo es notificar la presencia de Cooperia curticei en intestino delgado de un ovino proveniente de la localidad de Cerrillos en Salta. En el intestino delgado se determinó una carga de 600 formas adultas de Cooperia spp.Estas fueron identificadas como Cooperia curticei. Como características taxonómicas de relevancia las ramas del rayo dorsal se curvaban hacia atrás mostrando una forma de lira. En cuanto a las espículas, midieron en promedio 146,8 µm (± 5,24), con una concavidad marcada en parte media del cuerpo y con un tallo con una curvatura final similar a un pie. Este hallazgo constituye el primero en su tipo en la región del NOA y demuestra la adaptación de C. curticei a un clima de tipo serrano sub-andino. Este trabajo complementa lo descripto previamente en la región, en donde se menciona la presencia de Cooperia spp en ovinos, sin especificar su especie.

Abstract Cooperia curticei is a nematode related to sheep that is housed in the small intestine. Its presence in Argentina has been reported in environments such as the semi-arid region in the Pampa, the sub-humid Pampas in Buenos Aires and in the subtropical region in Corrientes. The objective of this work is to report the presence of Cooperia curticei in the small intestine of a sheep from the town of Cerrillos in Salta. A worm burden of 600 adult forms of Cooperia spp. was determined in the small intestine. These were identified as Cooperia curticei. As relevant taxonomic features the branches of the dorsal ray curved backwards showing a lyre shape. As for the spicules, they measured an average of 146.8 µm (± 5.24), with a marked concavity in the middle part of the body and with a stem with a final curvature similar to a foot. This finding is the first of its kind in the NOA region and demonstrates the adaptation of C. curticei to a sub-Andean mountain type climate. This work complement that previously described in the region, where the presence of Cooperia spp. in sheep was described but without species determination.

Route of administration influences the concentration of ivermectin reaching nematode parasites in the gastrointestinal tract of cattle.

An animal trial was conducted to measure the concentrations of ivermectin occurring in abomasal and small intestinal contents and mucosa, and in the target parasites (Ostertagia ostertagi and Cooperia oncophora) following administration by subcutaneous, oral and pour-on routes. Twenty-five steers were infected with ivermectin-resistant isolates of O. ostertagi and C. oncophora and following patency randomly allocated to 3 treatment groups of 7 and 1 untreated control group of four. On day 0, animals in the treatment groups were administered ivermectin via the oral, injectable or pour-on routes. On days 1, 2, 3, 4, 5, 6 and 8, blood samples were collected from all live animals, one animal from each treatment group was euthanised and the abomasum and small intestine recovered. Control animals were euthanised on each of days 4, 5, 6 and 8. Samples of gastrointestinal tract organs, their contents, mucosa and parasites were collected and assayed for ivermectin concentration using HPLC. The highest plasma concentrations occurred following subcutaneous administration. In the gastrointestinal contents the highest levels occurred following oral administration, although one high value occurred following pour-on administration, which was attributed to self-licking by the treated animal. The lowest GI content levels followed subcutaneous injection. Ivermectin concentrations in the gastrointestinal mucosa were highest following subcutaneous injection. Drug levels in the abomasal parasite O. ostertagi were most closely correlated with levels in the abomasal mucosa whereas levels in the intestinal C. oncophora were most closely correlated with those in the intestinal contents. Thus, the maximun levels of drug reached C. oncophora in the small intestine following oral administration. In contrast, the highest levels of ivermectin in O. ostertagi followed subcutaneous injection. Therefore, route of administration is likely to influence the exposure to ivermectin for different parasite species.

Host specificity and phylogeny of Trichostrongylidae of domestic ruminants in the Guinea savannah of the Adamawa plateau in Cameroon.

Gastro-intestinal tracts were examined from thirteen Gudali zebu cattle, ten goats and ten sheep from the Adamawa highland in Northern Cameroon. A total of 28,325 adult helminths were recovered from the abomasa, small and large intestines. Five trichostrongylid genera were identified by their morphology: Haemonchus, Trichostrongylus and Oesophagostomum were predominant in both cattle and small ruminants, whilst Cooperia was only found in cattle both in the abomasum and small intestines. The molecular species identification and the inference of their phylogenetic relationships was based on the analysis of the hypervariable region I of the small subunit 18S rDNA (SSU) and the Second Internal Transcribed Spacer (ITS-2) of 408 adult trichostrongylid worms, which were PCR-amplified, sequenced, and compared with available database entries. Consistent with earlier findings, the SSU was invariable within the Haemonchus and Trichostrongylus genera, confirming the prior classification based on the morphology of the worms, but the ITS-2 was highly inter- and intraspecifically variable and thus allowed to distinguish individual species and to study the haplotype diversity within the different species. In cattle, we report for the first time in Cameroon co-infection with two species of Haemonchus (H. placei and H. similis), together with two species of Cooperia (C. punctata and C. pectinata) and one species of Trichostrongylus (T. axei). In goats and sheep, we found one highly polymorphic clade of Haemonchus contortus and two Trichostrongylus species (T. axei and T. colubriformis). When compared with other Trichostrongylidae from different regions of the world and wildlife, the analysis of haplotypes did not indicate any host and geographical isolation, but a very high haplotype diversity among H. contortus. These findings illustrate the complexity of trichostrongylid populations in domestic ruminants and suggest grazing overlap between domestic and wildlife hosts.

A Revised Checklist of Cooperia Nematodes (Trichostrogyloidea), Common Parasites of Wild and Domestic Ruminants.

This review updates the current knowledge on the taxonomy of intestinal nematodes of the genus Cooperia parasitizing in wild and domestic ruminants. The emphasis is put on revision of 19 valid species belonging to the genus. This analysis focuses on main features of the genus Cooperia, including its geographic occurrence and the life cycle details. The most widespread congeners are Cooperia curticei, C. oncophora, C. pectinata, and C. punctata, having nearly worldwide distribution. The fifth species, referred by electronic databases from the European territory as Cooperia asamati Spiridonov, 1985, is unveiled here originally as nomen nudum.

Motility based assays using cultured fourth stage larvae fail to provide consistent discrimination between known avermectin-resistant and -susceptible isolates of Cooperia spp.

The fecal egg count reduction test (FECRT) is the only method commonly used for diagnosing anthelmintic resistance in gastrointestinal nematodes of cattle, but this method has several drawbacks that have limited its widescale implementation. Consequently, there exists a need to develop better methods for diagnosing resistance. Assays based on larval motility are used commonly for screening potential drug candidates, and for detecting drug resistance, but previous work in our lab demonstrated that the L3 stage failed to discriminate between avermectin-resistant and susceptible isolates of Cooperia spp. We hypothesized that the L4 may be a better stage for this purpose because it is a parasitic and actively feeding life stage without a double cuticle. L3 larvae of Cooperia spp. were exsheathed and cultured to L4 by maintaining them in media at 37 °C and 20 % CO2, with media changes and observation every 48 h for nine days. Three avermectin-resistant and two avermectin-susceptible GIN isolates (diagnosed by FECRT) containing >88 % Cooperia spp., were used. Three biological replicates were performed for each parasite isolate using both eprinomectin and ivermectin. Eleven drug concentrations from 0.01um to 40um and negative controls were evaluated. Motility readings were taken using the Worminator system before addition of the drug and at 24- and 48 -hs post drug exposure. Resistance ratios for ivermectin and eprinomectin ranged from 0.35 to 2.75 and 0.54-1.03, respectively. Though significant differences (p < 0.05) in percent inhibition were found at some drug concentrations in some assays, there were no consistent significant differences in the dose-response between susceptible and resistant isolates. Inhibition was greater in about half of the assays for the susceptible isolates, and in half the assays for the resistant isolates. The lack of consistency in these data indicate that motility of L4 is not a reliable diagnostic phenotype for measuring resistance to avermectin drugs in Cooperia spp.

Anthelmintic resistance among gastrointestinal nematodes of cattle on dairy calf to beef farms in Ireland.

BACKGROUND: The control of gastrointestinal nematodes (GIN) of cattle in pasture-based production systems such as Ireland is highly dependent on the availability of efficacious anthelmintics. There is very little information available on the efficacy of the broad-spectrum anthelmintics against GIN of cattle in Ireland and the aim of this study was to determine the prevalence of anthelmintic resistance on dairy calf to beef farms. RESULTS: GIN burden was monitored on thirty-six recruited farms by performing herd level faecal egg counts (FEC) every 2 weeks. Of these, nine farms were lost from the study as calves were treated with an anthelmintic for Dictyocaulus viviparus, two were lost as they treated for GIN, one dropped out of the study and on one the herd FEC did not reach the threshold for carrying out the Faecal Egg Count Reduction Test (FECRT). On the remaining 23 farms, once the herd FEC reached 100 eggs per gram, a FECRT was carried out. Pre and post-treatment larval cultures were also performed to identify the GIN to genus level. The efficacy of fenbendazole, levamisole, ivermectin and moxidectin was evaluated on 15, 11, 16 and 11 farms respectively. Resistance to fenbendazole was identified on 9 farms (60%) with resistance suspected on a further farm. Resistance to levamisole, ivermectin and moxidectin was detected on 2 (18%), 16 (100%) and 8 (73%) farms respectively. The predominant genera detected pre and post-treatment were Cooperia and Ostertagia with both genera detected post-treatment with fenbendazole and ivermectin. Due to the low proportion of Ostertagia spp. pre-treatment, the efficacy of levamisole or moxidectin against this genus could not be reliably established. CONCLUSIONS: Anthelmintic resistance was widespread on the sampled dairy calf to beef farms in Ireland with resistance to benzimidazole, levamisole, ivermectin and moxidectin detected.