Onchocerciasis Drug Discovery: In Vitro Evaluation of FDA-Approved Drugs against Onchocerca gutturosa in Gambia

Onchocerciasis treatment and control relies mainly on the use of ivermectin which has high activity against the microfilarial stage of Onchocerca volvulus but limited activity against the long-lived, tissue dwelling adult nematodes. As this neglected tropical disease has now been targeted for elimination, there is an urgent need for new drugs to combat these parasites, ideally with macrofilaricidal activity. In this study, we have examined the anti-Onchocerca activity of a range of existing FDA-approved drugs with a view to repurposing, which can lead to rapid and relatively inexpensive development. From the Pharmakon-1600 library, 106 drugs were selected and tested against O. gutturosa adult male parasites using a concentration of 1.25 × 10-5 M in an in vitro 5-day standard assay to assess motility and viability (using MTT/formazan colorimetry). The findings revealed that 44 drugs produced marginal/moderate activity (50-99% motility and/or MTT reductions) including cefuroxime sodium, methenamine, primaquine phosphate and rivastigmine tartrate, while 23 drugs produced good activity (100% motility reductions and significant MTT reductions), including atovaquone, isradipine, losartan, rifaximin, cefaclor and pyrantel pamoate. Although this study represents only a first step, some of the identified hits indicate there are potential anti-Onchocerca drug candidates worthy of further investigation.

Understanding the pathogenic mechanisms and therapeutic effects in neurocysticercosis

Despite being a leading cause of acquired seizures in endemic regions, the pathological mechanisms of neurocysticercosis are still poorly understood. This study aims to investigate the impact of anthelmintic treatment on neuropathological features in a rat model of neurocysticercosis. Rats were intracranially infected with Taenia solium oncospheres and treated with albendazole + praziquantel (ABZ), oxfendazole + praziquantel (OXF), or untreated placebo (UT) for 7 days. Following the last dose of treatment, brain tissues were evaluated at 24 h and 2 months. We performed neuropathological assessment for cyst damage, perilesional brain inflammation, presence of axonal spheroids, and spongy changes. Both treatments showed comparable efficacy in cyst damage and inflammation. The presence of spongy change correlated with spheroids counts and were not affected by anthelmintic treatment. Compared to white matter, gray matter showed greater spongy change (91.7% vs. 21.4%, p < 0.0001), higher spheroids count (45.2 vs. 0.2, p = 0.0001), and increased inflammation (72.0% vs. 21.4%, p = 0.003). In this rat model, anthelmintic treatment destroyed brain parasitic cysts at the cost of local inflammation similar to what is described in human neurocysticercosis. Axonal spheroids and spongy changes as markers of damage were topographically correlated, and not affected by anthelmintic treatment.

Effects of macrocyclic lactone anthelmintics on seed germination of temperate grassland species

Macrocyclic lactone anthelmintics are widely used to control invertebrate pests in livestock, such as sheep. While anthelmintic effects on non-target animals, such as dung-dwelling insects, are well studied, effects on seed germination are largely unknown. Seeds can come into contact with anthelmintics either during passage through the gastro-intestinal tract of grazing animals or when anthelmintics are excreted with their dung into the environment, which may result in changed germination patterns. We used four commonly applied macrocyclic lactones to assess their effects on germination: moxidectin, ivermectin, abamectin and doramectin as pure substances; moxidectin and ivermectin also in formulated form. We tested these pharmaceuticals on 17 different temperate grassland species from five plant families. Seeds were exposed to three concentrations of macrocyclic lactones (0.1, 1.0 and 10.0 mg·l-1 ) under controlled conditions, and germination was assessed over a 6-week period. From these data, we calculated germination percentage, mean germination time and germination synchrony. Most of the tested species were significantly affected in germination percentage and/or mean germination time by at least one of the tested pharmaceuticals, with formulated moxidectin having the largest impact. In general, the effects found were species- and pharmaceutical-specific. While formulated substances generally reduced germination percentage and increased mean germination time, pure substances increased germination percentage. Synchrony showed less clear patterns in all pharmaceuticals. Although effect size and sign varied between species, our study shows that non-target effects of macrocyclic lactones commonly occur in terrestrial plants. This may impede successful seed exchange between habitats via sheep, and even translate into profound changes to grazed ecosystems.

Horse and donkey parasitology: differences and analogies for a correct diagnostic and management of major helminth infections

In June 2022, at the XXXII Conference of the Italian Society of Parasitology, the parallels of the main endoparasitic infections of horses and donkeys were discussed. Although these 2 species are genetically different, they can be challenged by a similar range of parasites (i.e. small and large strongyles, and Parascaris spp.). Although equids can demonstrate some level of resilience to parasites, they have quite distinct helminth biodiversity, distribution and intensity among different geographical locations and breeds. Heavily infected donkeys may show fewer clinical signs than horses. Although parasite control is primarily provided to horses, we consider that there may be a risk of drug-resistance parasitic infection through passive infection in donkeys when sharing the same pasture areas. Knowing the possible lack of drug efficacy (<90 or 80%), it is advocated the use of selective treatment for both species based on fecal egg counts. Adult horses should receive treatment when the threshold exceeds 200–500 eggs per gram (EPG) of small strongyles. Moreover, considering that there are no precise indications in donkeys, a value >300 EPG may be a safe recommendation. We have highlighted the main points of the discussion including the dynamics of helminth infections between the 2 species.

Association of anthelmintic treatment with malaria prevalence in Rural Sussundenga, Mozambique

Background: Mozambique has the 4 th highest malaria incidence and mortality globally. Despite the existing malaria control strategies, malaria prevalence remains stagnant. These challenges have increased calls for innovative strategies in areas with the highest disease burden. Community mass treatment with anthelmintic agents have been used as an effective tool for the control of major helminth infections and has emerged as a potential tool for vector control in the fight against malaria. Methods: This was an analysis of data from a cross-sectional community-based survey designed to study malaria risk, prevention, and health seeking behaviors in Sussundenga, Mozambique. Using logistic regression models, we quantified the association between ever receiving anthelmintic treatment and P. falciparum infection. We also fit models to determine the association between recent anthelmintic treatment and malaria infection. Results: Two-hundred, seventy-seven (277) participants from 83 households were included in this analysis. The prevalence of P. falciparum infection measured by rapid diagnostic test (RDT) was 30%. 77% of participants reported having ever received anthelmintics. The prevalence of malaria was slightly higher among participants who reported ever taking anthelmintics. There was no statistically significant association between prior receipt of anthelmintic and P. falciparum malaria infection after adjusting for age, ITN use and head of household full-time employment (OR = 1.37, 95% CI, 0.70-2.70, p = 0.36). However, recent intake of anthelmintics was associated with lower odds of testing positive for in the adjusted models (OR = 0.35, 95% CI, 0.07-1.80, p = 0.21), but this was not statistically significant. Conclusions: Our findings show that the benefit of anthelmintics treatment as a control tool for P. falciparum malaria infection is likely tied to when it is administered rather than if it was ever administered. These findings offer evidence for making decisions in planning mass community deworming in sub-Saharan Africa.

Simultaneous Determination of Multiple Contaminants in Chicken Liver Using Dispersive Liquid-Liquid Microextraction (DLLME) Detected by LC-HRMS/MS

Simultaneous determination of a mixture of food contaminants, including pesticides, sulphonamides, fluoroquinolones, anthelmintics, and aflatoxin B1, in solid biological samples (chicken liver) by dispersive liquid-liquid microextraction/liquid chromatography-high resolution mass spectrometry (DLLME/LC-HRMS) is presented. Previous work focused on the application of DLLME to single-class contaminants. In this work, the DLLME extraction method has been extended to complex multiresidues in the biological matrix. The first part of this study was the selection of an appropriate solvent that enabled the dissolution of analytes from the chicken livers. The matrix-matched calibration curves showed good linearity in the range 0.5-50.0 µg kg^-1 for aflatoxin B1 and 50-500 µg kg^-1 for pesticides, fluoroquinolones, sulphonamides, and anthelmintics, with a coefficient of determination (R²) values of 0.9916-0.9967. The mean recoveries were in the range of 80.4-96.3%, and the relative standard deviation (RSD) values were in the range of 1.53-8.98%. The limit of detection (LOD) and the limit of quantification (LOQ) values were 0.03 µg kg^-1 and 0.09 µg kg^-1, respectively, for aflatoxin B1, and for pesticides, fluoroquinolones, sulphonamides, and anthelmintics, they were in the range of 0.011-1.197 µg kg^-1 and 0.150-2.579 µg kg^-1, respectively. The developed method was compared with the standard solid phase extraction (SPE) method, and there was no significant difference between the two methods.

Analysis, Occurrence and Exposure Evaluation of Antibiotic and Anthelmintic Residues in Whole Cow Milk from China

An optimized QuEChERS method for the simultaneous extraction of 26 antibiotics and 19 anthelmintics in whole cow milk was established, followed by UHPLC-MS/MS analysis. Briefly, 20 mL acetonitrile with 1 g disodium hydrogen citrate, 2 g sodium citrate, 4 g anhydrous MgSO₄, and 1 g sodium chloride were added to 10 g milk for target chemical extraction, followed by 50 mg anhydrous MgSO₄ for purification. Satisfactory recoveries were obtained using the modified QuEChERS method, with recoveries of the antibiotics ranging from 79.7 to 117.2%, with the exception of norfloxacin, which was at 53.4%, while those for anthelmintics were in the range of 73.1-105.1%. The optimized QuEChERS method presented good precision, with relative standard deviations ranging from 7.2 to 18.6% for both antibiotics and anthelmintics. The method was successfully applied to analyze the antibiotics and anthelmintics in 56 whole cow milk samples from China. Briefly, the detection frequencies and concentrations of most of the antibiotics and anthelmintics were low in the whole cow milk samples, with concentrations ranging from below LOD to 4296.8 ng/kg. Fenbendazole, febantel, enrofloxacin, levofloxacin, sulfadiazine, and sulfamethoxazole were the predominant drug residues in the whole cow milk samples. Spatial distribution was found for those antibiotics and anthelmintics with detection frequency higher than 50%, especially for the antibiotics, indicating regional differences in drug application. Based on the current study, exposure to antibiotics and anthelmintics through whole cow milk consumption are lower than the acceptable daily intake values suggested by the China Institute of Veterinary Drug Control. However, long-term exposure to low doses of antibiotics and anthelmintics still needs attention and merits further study.

Perspective on Schistosomiasis Drug Discovery: Highlights from a Schistosomiasis Drug Discovery Workshop at Wellcome Collection, London, September 2022

In September 2022, the Drug Discovery Unit at the University of Dundee, UK, organised an international meeting at the Wellcome Collection in London to explore the current clinical situation and challenges associated with treating schistosomiasis. The aim of this meeting was to discuss the need for new treatments in view of the clinical situation and to ascertain what the key requirements would be for any potential new anti-schistosomals. This information will be essential to inform ongoing drug discovery efforts for schistosomiasis. We also discussed the potential drug discovery pathway and associated criteria for progressing compounds to the clinic. To date, praziquantel (PZQ) is the only drug available to treat all species causing schistosomiasis, but it is often unable to completely clear parasites from an infected patient, partially due to its inactivity against juvenile worms. PZQ-mediated mass drug administration campaigns conducted in endemic areas (e.g., sub-Saharan Africa, where schistosomiasis is primarily prevalent) have contributed to reducing the burden of disease but will not eliminate the disease as a public health problem. The potential for Schistosoma to develop resistance towards PZQ, as the sole treatment available, could become a concern. Consequently, new anthelmintic medications are urgently needed, and this Perspective aims to capture some of the learnings from our discussions on the key criteria for new treatments.

Chemical modulation of Schistosoma mansoni lysine specific demethylase 1 (SmLSD1) induces wide-scale biological and epigenomic changes

Background: Schistosoma mansoni, a parasitic worm species responsible for the neglected tropical disease schistosomiasis, undergoes strict developmental regulation of gene expression that is carefully controlled by both genetic and epigenetic processes. As inhibition of S. mansoni epigenetic machinery components impairs key transitions throughout the parasite's digenetic lifecycle, a greater understanding of how epi-drugs affect molecular processes in schistosomes could lead to the development of new anthelmintics. Methods:   In vitro whole organism assays were used to assess the anti-schistosomal activity of 39 Homo sapiens Lysine Specific Demethylase 1 (HsLSD1) inhibitors on different parasite life cycle stages. Moreover, tissue-specific stains and genomic analysis shed light on the effect of these small molecules on the parasite biology. Results: Amongst this collection of small molecules, compound 33 was the most potent in reducing ex vivo viabilities of schistosomula, juveniles, miracidia and adults. At its sub-lethal concentration to adults (3.13 µM), compound 33 also significantly impacted oviposition, ovarian as well as vitellarian architecture and gonadal/neoblast stem cell proliferation. ATAC-seq analysis of adults demonstrated that compound 33 significantly affected chromatin structure (intragenic regions > intergenic regions), especially in genes differentially expressed in cell populations (e.g., germinal stem cells, hes2 + stem cell progeny, S1 cells and late female germinal cells) associated with these ex vivo phenotypes. KEGG analyses further highlighted that chromatin structure of genes associated with sugar metabolism as well as TGF-beta and Wnt signalling were also significantly perturbed by compound 33 treatment. Conclusions: This work confirms the importance of histone methylation in S. mansoni lifecycle transitions, suggesting that evaluation of LSD1 - targeting epi-drugs may facilitate the search for next-generation anti-schistosomal drugs. The ability of compound 33 to modulate chromatin structure as well as inhibit parasite survival, oviposition and stem cell proliferation warrants further investigations of this compound and its epigenetic target SmLSD1.

Roles of Essential Oils, Polyphenols, and Saponins of Medicinal Plants as Natural Additives and Anthelmintics in Ruminant Diets: A Systematic Review

Public awareness on health and safety issues in using antibiotics for livestock production has led many countries to ban the use of all growth-promoting antibiotics (GPA) for livestock feeding. The ban on the utilization of antibiotics in livestock, on the other hand, is an opportunity for researchers and livestock practitioners to develop alternative feed additives that are safe for both livestock and the consumers of animal derived foods. Many feed additives were developed from a number of plants that contain secondary metabolites, such as essential oils, polyphenols, and saponins. These secondary metabolites are extracted from various parts of many types of plants for their uses as feed additives and anthelmintics. Recent investigations on using essential oils, polyphenols, and saponins as dietary additives and anthelmintics demonstrate that they can increase not only the production and health of ruminants but also ensure the safety of the resulting foods. There are many publications on the advantageous impacts of dietary plant bioactive components on ruminants; however, a comprehensive review on individual bioactive constituents of each plant secondary metabolites along with their beneficial effects as feed additives and anthelmintics on ruminants is highly required. This current study reviewed the individual bioactive components of different plant secondary metabolites and their functions as additives and anthelmintics to improve ruminant production and health, with respect to safety, affordability and efficiency, using a systematic review procedure.

Pharmacological Profiling of a Brugia malayi Muscarinic Acetylcholine Receptor as a Putative Antiparasitic Target

The diversification of anthelmintic targets and mechanisms of action will help ensure the sustainable control of nematode infections in response to the growing threat of drug resistance. G protein-coupled receptors (GPCRs) are established drug targets in human medicine but remain unexploited as anthelmintic substrates despite their important roles in nematode neuromuscular and physiological processes. Bottlenecks in exploring the druggability of parasitic nematode GPCRs include a limited helminth genetic toolkit and difficulties establishing functional heterologous expression. In an effort to address some of these challenges, we profile the function and pharmacology of muscarinic acetylcholine receptors in the human parasite Brugia malayi, an etiological agent of human lymphatic filariasis. While acetylcholine-gated ion channels are intensely studied as targets of existing anthelmintics, comparatively little is known about metabotropic receptor contributions to parasite cholinergic signaling. Using multivariate phenotypic assays in microfilariae and adults, we show that nicotinic and muscarinic compounds disparately affect parasite fitness traits. We identify a putative G protein-linked acetylcholine receptor of B. malayi (Bma-GAR-3) that is highly expressed across intramammalian life stages and adapt spatial RNA in situ hybridization to map receptor transcripts to critical parasite tissues. Tissue-specific expression of Bma-gar-3 in Caenorhabditis elegans (body wall muscle, sensory neurons, and pharynx) enabled receptor deorphanization and pharmacological profiling in a nematode physiological context. Finally, we developed an image-based feeding assay as a reporter of pharyngeal activity to facilitate GPCR screening in parasitized strains. We expect that these receptor characterization approaches and improved knowledge of GARs as putative drug targets will further advance the study of GPCR biology across medically important nematodes.

Antiparasitic Tannin-Rich Plants from the South of Europe for Grazing Livestock: A Review

Internal parasites are one of the main causes of health threats in livestock production, especially in extensive livestock farming. Despite the environmental toxic effects (loss of dung beetles, biodiversity, and other issues) and resistance phenomenon derived from their prolonged use, anti-parasitic chemical pharmaceuticals are frequently used, even in organic farming. Such a situation within the context of climate change requires urgent exploration of alternative compounds to solve these problems and apparent conflicts between organic farming objectives regarding the environment, public health, and animal health. This review is focused on some plants (Artemisia spp., Cichorium intybus L., Ericaceae family, Hedysarum coronarium L., Lotus spp., Onobrychis viciifolia Scop.) that are well known for their antiparasitic effect, are voluntarily grazed and ingested, and can be spontaneously found or cultivated in southern Europe and other regions with a Mediterranean climate. The differences found between effectiveness, parasite species affected, in vitro/in vivo experiments, and active compounds are explored. A total of 87 papers where antiparasitic activity of those plants have been studied are included in this review; 75% studied the effect on ruminant parasites, where gastrointestinal nematodes were the parasite group most studied (70%), and these included natural (31%) and experimental (37%) infections.

Management of Rat Lungworm Disease (Neuroangiostrongyliasis) Using Anthelmintics: Recent Updates and Recommendations

While there have been legitimate concerns in the past regarding the use of anthelmintics for the management of neuroangiostrongyliasis (rat lungworm disease), recent studies demonstrate that they can be considered safe and efficacious, particularly albendazole, which is regarded as the choice anthelmintic for its management. However, physician hesitancy to prescribe, as well as problems of availability persist, at least in Hawaii, which is considered the epicenter of this disease in the US. As a result, many patients suffer a diminished quality of life or even death. Here, we discuss recent studies that provide insights into new treatments and preventative interventions, which can be more rigorously used for the management of neuroangiostrongyliasis. In summary, results from recent studies suggest that albendazole and avermectins are beneficial for post-exposure management, pyrantel pamoate is beneficial as a post-exposure prophylactic, and levamisole is deserving of further study for the treatment of neuroangiostrongyliasis.

Herbal anthelmintic agents: a narrative review

Helminths or Parasitic worms of humans may cause chronic and sometimes deadly diseases, considered as neglected tropical diseases (NTDs) that infect around two billion people worldwide. Plants have been used as anthelmintics from ancient times. This review is a compilation of plants as source of anthelmintic drug. All information presented in this review article regarding the anthelmintic activities of plants from 2005 and has been acquired by approaching various electronic databases, including Scopus, Google scholar, Web of science and PubMed. Literature was surveyed for anthelmintic activity of plants which showed that secondary metabolites of plants like terpenes, glycosides, saponins, flavonoids, tannins and alkaloids were having anthelmintic activity. Since this review is a compilation of anthelmintic activity of plants from the year 2005, it will definitely be a fruitful study for researchers working in this field.

Antiparasitic Drugs against SARS-CoV-2: A Comprehensive Literature Survey

More than two years have passed since the viral outbreak that led to the novel infectious respiratory disease COVID-19, caused by the SARS-CoV-2 coronavirus. Since then, the urgency for effective treatments resulted in unprecedented efforts to develop new vaccines and to accelerate the drug discovery pipeline, mainly through the repurposing of well-known compounds with broad antiviral effects. In particular, antiparasitic drugs historically used against human infections due to protozoa or helminth parasites have entered the main stage as a miracle cure in the fight against SARS-CoV-2. Despite having demonstrated promising anti-SARS-CoV-2 activities in vitro, conflicting results have made their translation into clinical practice more difficult than expected. Since many studies involving antiparasitic drugs are currently under investigation, the window of opportunity might be not closed yet. Here, we will review the (controversial) journey of these old antiparasitic drugs to combat the human infection caused by the novel coronavirus SARS-CoV-2.

Anthelmintic resistance of gastrointestinal nematodes in dairy calves within a pasture-based production system of south West Western Australia

The objective of this study was to determine the prevalence of gastrointestinal nematodes among post‐weaned calves aged between 4 and 12 months old within a pasture‐based system of south west Australia and quantify the level of anthelmintic resistance. Pre‐treatment FECs were monitored on 14 dairy farms. Anthelmintic resistance was assessed on 11 of the farms. Control FECs were compared with anthelmintic FECs at 14 days post‐treatment with doramectin (injectable), levamisole (oral), fenbendazole (oral) and a levamisole/abamectin combination (pour‐on). Results demonstrate a strong level of anthelmintic resistance, with at least one class of anthelmintic failing to achieve a 95% reduction in FEC in one or more gastrointestinal nematode species. Doramectin was fully effective against Ostertagia, but C. oncophora displayed resistance in 91% of the farms. Conversely, levamisole was fully effective against C. oncophora, but Ostertagia displayed resistance in 80% of the farms. Fenbendazole resistance was present in both C. onocphora and Ostertagia in 64% and 70% of the farms, respectively. Trichostrongylus showed low resistance, occurring in doramectin (14%) and levamisole/abamectin combination (14%). This study confirms that anthelmintic resistance is common. Regular FEC reduction testing is recommended to monitor and guide decision‐making for appropriate anthelmintic usage.

Benzimidazole-carbamate anthelmintics: Perspective candidates for the anticancer drug development

Cellular oncogenesis involves a complex interplay between the several synchronized, interdependent pathways that collectively determine the pathogenesis and pathophysiology of cancer. Limited therapeutic success with the existing anticancer drugs drew huge interest in the design and development of new pharmacophores with improved clinical efficacy, however despite huge investments in anticancer RD; the average number of Food and Drug Administration-approved anticancer drugs declined since the 1990s. The contemporary anticancer medications possess high attrition rates, bear substantial costs, and experience low efficacy owing to the drug resistance expressed by the aggressive tumors. Mainly, the translation of novel candidate anticancer drugs into clinical practice, their commercialization, and transformation from the bench to bedside require a long timeframe of 10-15 years and capital worth millions of dollars. The repurposing strategy substantially accelerated the anticancer drug development regime as the approved drugs with tested safety and efficacy ensure a minimal risk of failure, and nominal R&D expenses as anticipated for the newly identified candidate drugs yet to enter the clinical trials. In addition, the repurposed drugs ensure a rapid clinical translation due to a validated clinical profile and their ability to target the identified hallmarks and hitherto unknown vulnerabilities of cancer. The flagship project "Repurposing Drugs in Oncology" (ReDO) identified 268 "hard repurposing" noncancer medications as candidate drugs with a promising anticancer profile (https://www.anticancerfund.org/en/redo-db). However, the generic profile of 84% of repurposed drugs in ReDO data set discourages the commercial sponsors from funding the repurposing trials, especially the Phase III efficacy trials that require significant capital.

A validated high-throughput method for assaying rat lungworm (Angiostrongylus cantonensis) motility when challenged with potentially anthelmintic natural products from Hawaiian fungi

Parasitic nematodes devastate human and animal health. The limited number of anthelmintics available is concerning, especially because of increasing drug resistance. Anthelmintics are commonly derived from natural products, e.g. fungi and plants. This investigation aimed to develop a high-throughput whole organism screening method based on a motility assay using the wMicroTracker system. Anthelmintic activity of extracts from Hawaiian fungi was screened against third-stage larvae of the parasitic nematode Angiostrongylus cantonensis , categorized according to the degree of motility reduction. Of the 108 crude samples and fractionated products, 48 showed some level of activity, with 13 reducing motility to 0–25% of the maximum exhibited, including two pure compounds, emethacin B and epicoccin E, neither previously known to exhibit anthelmintic properties. The process of bioassay-guided fractionation is illustrated in detail based on analysis of one of the crude extracts, which led to isolation of lamellicolic anhydride, a compound with moderate activity. This study validates the wMicroTracker system as an economical and high-throughput option for testing large suites of natural products against A. cantonensis , adds to the short list of diverse parasites for which it has been validated and highlights the value of A. cantonensis and Hawaiian fungi for discovery of new anthelmintics.

Categorisation of Antimicrobial Use in Fijian Livestock Production Systems

Antimicrobial resistance (AMR) is a major global threat to human and animal health. The use of antimicrobials in the livestock sector is considered to contribute to AMR. Therefore, a reduction in and prudent use of antimicrobials in livestock production systems have been advocated. This cross-sectional survey aimed to investigate the extent of imprudent antimicrobial use (AMU) and to determine whether the AMU practice was affected by either the farming system or species of farmed livestock in the largest island (Viti Levu) of Fiji. A total of 276 livestock enterprises were surveyed and antimicrobials were used on 309 occasions over 90 days. Overall, in 298 of 309 (96%) incidents, antimicrobials were used imprudently, comprising antibiotics, 160 of 170 (94%) and anthelmintics, 138 of 139 (99%). Prudent use of antibiotics was associated with commercial farming systems (X2 = 13, p = 0.001), but no association was observed with anthelmintic use (p > 0.05). Imprudent antibiotic use was associated with dairy (OR = 7.6, CI = 1.41, 41.57, p = 0.018) followed by layer and beef (p > 0.05) compared to broiler enterprises. Imprudent AMU was more common in the backyard and semi-commercial enterprises compared to commercial broiler enterprises. Policies promoting the prudent use of antimicrobials in Fiji should focus on smaller livestock production systems and enterprises.

A High-Throughput Phenotypic Screen of the 'Pandemic Response Box' Identifies a Quinoline Derivative with Significant Anthelmintic Activity

Parasitic nematodes cause diseases in livestock animals and major economic losses to the agricultural industry worldwide. Nematodes of the order Strongylida, including Haemonchus contortus, are particularly important. The excessive use of anthelmintic compounds to treat infections and disease has led to widespread resistance to these compounds in nematodes, such that there is a need for new anthelmintics with distinctive mechanisms of action. With a focus on discovering new anthelmintic entities, we screened 400 chemically diverse compounds within the 'Pandemic Response Box' (from Medicines for Malaria Venture, MMV) for activity against H. contortus and its free-living relative, Caenorhabditis elegans-a model organism. Using established phenotypic assays, test compounds were evaluated in vitro for their ability to inhibit the motility and/or development of H. contortus and C. elegans. Dose-response evaluations identified a compound, MMV1581032, that significantly the motility of H. contortus larvae (IC₅₀ = 3.4 ± 1.1 μM) and young adults of C. elegans (IC₅₀ = 7.1 ± 4.6 μM), and the development of H. contortus larvae (IC₅₀ = 2.2 ± 0.7 μM). The favourable characteristics of MMV1581032, such as suitable physicochemical properties and an efficient, cost-effective pathway to analogue synthesis, indicates a promising candidate for further evaluation as a nematocide. Future work will focus on a structure-activity relationship investigation of this chemical scaffold, a toxicity assessment of potent analogues and a mechanism/mode of action investigation.

The ATP bioluminescence assay: a new application and optimization for viability testing in the parasitic nematode Haemonchus contortus

The parasitic gastrointestinal nematode Haemonchus contortus causes serious economic losses to agriculture due to infection and disease in small ruminant livestock. The development of new therapies requires appropriate viability testing, with methods nowadays relying on larval motility or development using procedures that involve microscopy. None of the existing biochemical methods, however, are performed in adults, the target stage of the anthelmintic compounds. Here we present a new test for the viability of H. contortus adults and exsheathed third-stage larvae which is based on a bioluminescent assay of ATP content normalized to total protein concentration measured using bicinchoninic acid. All the procedure steps were optimized to achieve maximal sensitivity and robustness. This novel method can be used as a complementary assay for the phenotypic screening of new compounds with potential antinematode activity in exsheathed third-stage larvae and in adult males. Additionally, it might be used for the detection of drug-resistant isolates.

Chromosome-scale assembly and whole-genome sequencing of 266 giant panda roundworms provide insights into their evolution, adaptation and potential drug targets

Helminth diseases have long been a threat to the health of humans and animals. Roundworms are important organisms for studying parasitic mechanisms, disease transmission and prevention. The study of parasites in the giant panda is of importance for understanding how roundworms adapt to the host. Here, we report a high‐quality chromosome‐scale genome of Baylisascaris schroederi with a genome size of 253.60 Mb and 19,262 predicted protein‐coding genes. We found that gene families related to epidermal chitin synthesis and environmental information processes in the roundworm genome have expanded significantly. Furthermore, we demonstrated unique genes involved in essential amino acid metabolism in the B. schroederi genome, inferred to be essential for the adaptation to the giant panda‐specific diet. In addition, under different deworming pressures, we found that four resistance‐related genes (glc‐1, nrf‐6, bre‐4 and ced‐7) were under strong positive selection in a captive population. Finally, 23 known drug targets and 47 potential drug target proteins were identified. The genome provides a unique reference for inferring the early evolution of roundworms and their adaptation to the host. Population genetic analysis and drug sensitivity prediction provide insights revealing the impact of deworming history on population genetic structure of importance for disease prevention.

Computational repurposing of benzimidazole anthelmintic drugs as potential colchicine binding site inhibitors

Background: Although some benzimidazole-based anthelmintic drugs are found to possess anticancer activity, their modes of binding interactions have not been reported. Methodology: In this study, we aimed to investigate the binding interactions and electronic configurations of nine benzimidazole-based anthelmintics against one of the well-known cancer targets (tubulin protein). Results: Binding affinities of docked benzimidazole drugs into colchicine-binding site were calculated where flubendazole > oxfendazole > nocodazole > mebendazole. Flubendazole was found to bind more efficiently with tubulin protein than other drugs. Quantum mechanics studies revealed that the electron density of HOMO of flubendazole and mebendazole together with their molecular electrostatic potential map are closely similar to that of nocodazole. Conclusion: Our study has ramifications for considering repurposing of flubendazole as a promising anticancer candidate.

Survey of anthelmintic use in South American camelids in the UK

BACKGROUND

Gastrointestinal helminths are common in South American camelids in the UK. However, there are no anthelmintics currently licenced for camelids, leading to a limited evidence base for treatment. The aim of this study was to assess the usage of anthelmintics among UK camelid farmers.

METHODS

An online questionnaire focusing on the use of anthelmintics in camelids was distributed to UK camelid owners in Spring 2019.

RESULTS

Forty-nine of the 51 respondents treated their camelids with anthelmintics, while 21 (42.0%) reported a previous gastrointestinal helminth diagnosis on their farms. A wide variety of anthelmintics were employed and there was striking variation in treatment frequency, dosage and source of information used to select anthelmintic dosing regimen.

CONCLUSION

This work highlights the need for quality efficacy studies of anthelmintics in camelids to provide an appropriate evidence base for treatment, as well as the need for better education for camelid owners on anthelmintics and anthelmintic resistance.

Clinical Efficacy and Safety of Albendazole and Other Benzimidazole Anthelmintics for Rat Lungworm Disease (Neuroangiostrongyliasis): A Systematic Analysis of Clinical Reports and Animal Studies

The safety and efficacy of benzimidazole anthelmintics for the treatment of rat lungworm disease (neuroangiostrongyliasis) have been questioned regardless of numerous experimental animal studies and clinical reports. In this review, 40 of these experimental animal studies and 104 clinical reports are compiled with a focus on albendazole. Among the 144 articles involving an estimated 1034 patients and 2561 animals, 4.1% were inconclusive or vague regarding the use of benzimidazoles. Of the remaining 138 articles, 90.5% found benzimidazoles to be safe and effective (885 patients, 2530 animals), 4.3% as safe but ineffective (73 patients, 3 animals), and 5.0% caused adverse reactions (7 patients, 28 animals). Among those clinical reports that described a confirmed diagnosis of neuroangiostrongyliasis in which albendazole monotherapy was used, 100% reported high efficacy (743 patients, 479 animals). In those where albendazole-corticosteroid co-therapy was used, 97.87% reported it to be effective (323 patients, 130 animals).

Soybean (Glycine max) Is Able to Absorb, Metabolize and Accumulate Fenbendazole in All Organs Including Beans

Although manure is an important source of minerals and organic compounds it represents a certain risk of spreading the veterinary drugs in the farmland and their permeation to human food. We tested the uptake of the anthelmintic drug fenbendazole (FBZ) by soybean, a common crop plant, from the soil and its biotransformation and accumulation in different soybean organs, including beans. Soybeans were cultivated in vitro or grown in a greenhouse in pots. FBZ was extensively metabolized in roots of in vitro seedlings, where sixteen metabolites were identified, and less in leaves, where only two metabolites were found. The soybeans in greenhouse absorbed FBZ by roots and translocated it to the leaves, pods, and beans. In roots, leaves, and pods two metabolites were identified. In beans, FBZ and one metabolite was found. FBZ exposure did not affect the plant fitness or yield, but reduced activities of some antioxidant enzymes and isoflavonoids content in the beans. In conclusion, manure or biosolids containing FBZ and its metabolites represent a significant risk of these pharmaceuticals entering food consumed by humans or animal feed. In addition, the presence of these drugs in plants can affect plant metabolism, including the production of isoflavonoids.

Cell Death and Transcriptional Responses Induced in Larvae of the Nematode Haemonchus contortus by Toxins/Toxicants with Broad Phylogenetic Efficacy

Establishing methods to investigate treatments that induce cell death in parasitic nematodes will promote experimental approaches to elucidate mechanisms and to identify prospective anthelmintics capable of inducing this outcome. Here, we extended recent progress on a method to monitor cell death and to identify small molecule inhibitors in Ascaris suum to Haemonchus contortus, a phylogenetically distant parasitic nematode of significance for both human and agricultural animal health. We utilized a diverse group of small molecule inhibitors referred to as nematode intestinal toxins/toxicants (NITs) coupled with motility, cytological and cell death assays to resolve gross effects on motility and individual cells and organ systems of two H. contortus larval stages in culture. Early transcriptional response evaluation identified NIT-responsive genes and pathways. The scope of death among cells in larvae varied among NITs but shared patterns with A. suum, despite the approach having some limitations due to characteristics of H. contortus larvae. Gene response patterns varied among NITs tested and provided information on the cell targets and pathways affected. Experimental NIT assays provide tools capable of inducing cell death in larval stages of parasitic nematodes, and can resolve many individual cells and organ systems in which cell death can be induced.

Current Status for Controlling the Overlooked Caprine Fasciolosis

Simple Summary

Retaining sustainable agricultural systems is essential to feed the expanding population. Helminth parasite infections impact livestock production values and yields, including infections in goats, which are often overlooked. There is a requirement to collate caprine-specific knowledge surrounding fasciolosis, caused by Fasciola hepatica and Fasciola gigantica (liver flukes). Current liver fluke control methods include drug application and pasture management. This review aims to outline goat-specific fasciolosis vaccine development and the potential for alternative control methods.

Abstract

The disease fasciolosis is caused by the liver flukes Fasciola hepatica and F. gigantica, which infect a wide range of mammals and production livestock, including goats. These flatworm parasites are globally distributed and predicted to cost the livestock industry a now conservative USD 3 billion per year in treatment and lowered on-farm productivity. Infection poses a risk to animal welfare and results in lowered fertility rates and reduced production yields of meat, milk and wool. This zoonotic disease is estimated to infect over 600 million animals and up to 2.4 million humans. Current and future control is threatened with the global emergence of flukes resistant to anthelmintics. Drug resistance calls for immediate on-farm parasite management to ensure treatments are effective and re-infection rates are kept low, while a sustainable long-term control method, such as a vaccine, is being developed. Despite the recent expansion of the goat industry, particularly in developing countries, there are limited studies on goat-focused vaccine control studies and the effectiveness of drug treatments. There is a requirement to collate caprine-specific fasciolosis knowledge. This review will present the current status of liver fluke caprine infections and potential control methods for application in goat farming.

Neurocysticercosis: Current Perspectives on Diagnosis and Management

Porcine cysticercosis, human taeniasis, and (neuro)cysticercosis are endemic in many low- and middle-income countries (LMIC) where they present a significant health burden to affected communities. Neurocysticercosis (NCC) is one of the leading causes of human epilepsy in many hyperendemic regions in Latin America, Asia, and sub-Saharan Africa. The World Health Organization (WHO) reports an estimated 2.5-8.3 million cases of NCC annually with a disability-adjusted life year (DALY) burden of 2.8 million, but as for all neglected tropical diseases (NTDs), these values are likely to be underestimated. Diagnosis of NCC is complex and most accurately diagnosed using clinical neuroimaging that is unavailable in most hyperendemic regions in LMIC. On January 28, 2021, WHO will launch its road map for the NTDs' "Ending the neglect to attain the Sustainable Development Goals: a road map for neglected tropical diseases 2021-2030." Taeniasis/cysticercosis is targeted for control success considered as steady increase in the number of countries with intensified control in hyperendemic areas [increasing from 2 (3%) in 2020 to 4 (6%) in 2023, to 9 (14%) by 2025, and to 17 (27%) by 2030]. Cross-cutting targets that include 100% access to at least basic water supply, sanitation, and hygiene in areas endemic for NTDs and 75% integrated treatment coverage for preventative chemotherapy will additionally impact on the taeniasis/cysticercosis/NCC complex. With no vaccine available for humans, prevention of infection depends on communication to the public of the life cycle of a complex zoonosis to promote behavior change, underpinned by practical control measures including treatment of human taeniasis and (neuro)cysticercosis with albendazole and praziquantel [widely used as part of the mass drug administration (MDA) deworming programs], surgery where appropriate, and effective vaccination and deworming for pigs supported by meat inspection. Here, we review recent advances in tools and implementation for Taenia solium taeniasis/(neuro)cysticercosis (TSTC) control and milestones on the onward path to elimination.

Three Small Molecule Entities (MPK18, MPK334 and YAK308) with Activity against Haemonchus contortus In Vitro

Due to widespread multi-drug resistance in parasitic nematodes of livestock animals, there is an urgent need to discover new anthelmintics with distinct mechanisms of action. Extending previous work, here we screened a panel of 245 chemically-diverse small molecules for anti-parasitic activity against Haemonchus contortus—an economically important parasitic nematode of livestock. This panel was screened in vitro against exsheathed third-stage larvae (xL3) of H. contortus using an established phenotypic assay, and the potency of select compounds to inhibit larval motility and development assessed in dose-response assays. Of the 245 compounds screened, three—designated MPK18, MPK334 and YAK308—induced non-wildtype larval phenotypes and repeatedly inhibited xL3-motility, with IC₅₀ values of 45.2 µM, 17.1 µM and 52.7 µM, respectively; two also inhibited larval development, with IC₅₀ values of 12.3 µM (MPK334) and 6.5 µM (YAK308), and none of the three was toxic to human liver cells (HepG2). These findings suggest that these compounds deserve further evaluation as nematocidal candidates. Future work should focus on structure–activity relationship (SAR) studies of these chemical scaffolds, and assess the in vitro and in vivo efficacies and safety of optimised compounds against adults of H. contortus.

Behavioral fingerprints predict insecticide and anthelmintic mode of action

Novel invertebrate-killing compounds are required in agriculture and medicine to overcome resistance to existing treatments. Because insecticides and anthelmintics are discovered in phenotypic screens, a crucial step in the discovery process is determining the mode of action of hits. Visible whole-organism symptoms are combined with molecular and physiological data to determine mode of action. However, manual symptomology is laborious and requires symptoms that are strong enough to see by eye. Here, we use high-throughput imaging and quantitative phenotyping to measure Caenorhabditis elegans behavioral responses to compounds and train a classifier that predicts mode of action with an accuracy of 88% for a set of ten common modes of action. We also classify compounds within each mode of action to discover substructure that is not captured in broad mode-of-action labels. High-throughput imaging and automated phenotyping could therefore accelerate mode-of-action discovery in invertebrate-targeting compound development and help to refine mode-of-action categories.

Determination of Anthelmintic and Antiprotozoal Drug Residues in Fish Using Liquid Chromatography-Tandem Mass Spectrometry

The objective of this study is to develop a comprehensive and simple method for the simultaneous determination of anthelmintic and antiprotozoal drug residues in fish. For sample preparation, we used the "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) method with a simple modification. The sample was extracted with water and 1% formic acid in acetonitrile/methanol (MeCN/MeOH) (95:5, v/v), followed by phase separation (salting out) with MgSO4 and NaCl (4:1, w/w). After centrifugation, an aliquot of the extract was purified by dispersive solid-phase extraction (d-SPE) prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The method was validated at three concentration levels for all matrices, in accordance with the Codex guidelines (CAC/GL-71). Quantitative analysis was performed using the method of matrix-matched calibration. The recoveries were between 60.6% and 119.9%, with coefficients of variation (CV) <30% for all matrices. The limit of quantitation (LOQ) of the method ranged from 0.02 μg kg-1 to 4.8 μg kg-1 for all matrices. This comprehensive method can be used for the investigation of both anthelmintic and antiprotozoal drugs belonging to different chemical families in fishery products.

A review of the maternal iron and folic acid supplementation programme in Nepal: Achievements and challenges

In the late 1990s, an estimated 75% of pregnant women in Nepal were anaemic. Although iron and folic acid (IFA) supplements were available free of charge, coverage among pregnant women was very low. In response, the Government of Nepal launched the Iron Intensification Programme (IIP) in 2003 to improve the coverage of IFA supplementation and anthelminthic treatment during pregnancy, as well as promote the utilization of antenatal care. This review examined how the IIP programme contributed to Nepal's success in increasing the consumption of IFA supplements during pregnancy. Nepal's cadre of Female Community Health Volunteers were engaged in the IIP to support the community‐based distribution of IFA supplements to pregnant women and complement IFA distribution through health facilities and outreach services. As a result, the country achieved a fourfold increase in the proportion of women who took IFA supplements during pregnancy between 2001 and 2016 (from 23% to 91%) and a 12‐fold increase in the proportion who took IFA supplements for at least 90 days during pregnancy (from 6% to 71%). The increase in coverage of IFA supplements accompanied an increase in the coverage of antenatal care during the same period. By 2016, the prevalence of anaemia in pregnant women decreased to 46%, highlighting the need to tackle other causes of anaemia and improve haemoglobin concentration before pregnancy, while maintaining the successful efforts to reach pregnant women with IFA supplements at the community level.

An Integrated Approach to Identify New Anti-Filarial Leads to Treat River Blindness, a Neglected Tropical Disease

Filarial worms cause multiple debilitating diseases in millions of people worldwide, including river blindness. Currently available drugs reduce transmission by killing larvae (microfilariae), but there are no effective cures targeting the adult parasites (macrofilaricides) which survive and reproduce in the host for very long periods. To identify effective macrofilaricides, we carried out phenotypic screening of a library of 2121 approved drugs for clinical use against adult Brugia pahangi and prioritized the hits for further studies by integrating those results with a computational prioritization of drugs and associated targets. This resulted in the identification of 18 hits with anti-macrofilaricidal activity, of which two classes, azoles and aspartic protease inhibitors, were further expanded upon. Follow up screening against Onchocerca spp. (adult Onchocerca ochengi and pre-adult O. volvulus) confirmed activity for 13 drugs (the majority having IC₅₀ < 10 μM), and a counter screen of a subset against L. loa microfilariae showed the potential to identify selective drugs that prevent adverse events when co-infected individuals are treated. Stage specific activity was also observed. Many of these drugs are amenable to structural optimization, and also have known canonical targets, making them promising candidates for further optimization that can lead to identifying and characterizing novel anti-macrofilarial drugs.

UDP-Glycosyltransferases and Albendazole Metabolism in the Juvenile Stages of Haemonchus contortus

The nematode Haemonchus contortus, a gastrointestinal parasite of ruminants, can severely burden livestock production. Although anthelmintics are the mainstay in the treatment of haemonchosis, their efficacy diminishes due to drug-resistance development in H. contortus. An increased anthelmintics inactivation via biotransformation belongs to a significant drug-resistance mechanism in H. contortus. UDP-glycosyltransferases (UGTs) participate in the metabolic inactivation of anthelmintics and other xenobiotic substrates through their conjugation with activated sugar, which drives the elimination of the xenobiotics due to enhanced solubility. The UGTs family, in terms of the biotransformation of commonly used anthelmintics, has been well described in adults as a target stage. In contrast, the free-living juvenile stages of H. contortus have attracted less attention. The expression of UGTs considerably varies throughout the life cycle of the juvenile nematodes, suggesting their different roles. Furthermore, the constitutive expression in a susceptible strain with two resistant strains shows several resistance-related changes in UGTs expression, and the exposure of juvenile stages of H. contortus to albendazole (ABZ) and ABZ-sulfoxide (ABZSO; in sublethal concentrations) leads to the increased expression of several UGTs. The anthelmintic drug ABZ and its primary metabolite ABZSO biotransformation, tested in the juvenile stages, shows significant differences between susceptible and resistant strain. Moreover, higher amounts of glycosidated metabolites of ABZ are formed in the resistant strain. Our results show similarly, as in adults, the UGTs and glycosidations significant for resistance-related differences in ABZ biotransformation and warrant further investigation in their individual functions.

Complementary Approaches with Free-living and Parasitic Nematodes to Understanding Anthelmintic Resistance

Anthelmintic drugs are the major line of defense against parasitic nematode infections, but the arsenal is limited and resistance threatens sustained efficacy of the available drugs. Discoveries of the modes of action of these drugs and mechanisms of resistance have predominantly come from studies of a related nonparasitic nematode species, Caenorhabditis elegans, and the parasitic nematode Haemonchus contortus. Here, we discuss how our understanding of anthelmintic resistance and modes of action came from the interplay of results from each of these species. We argue that this 'cycle of discovery', where results from one species inform the design of experiments in the other, can use the complementary strengths of both to understand anthelmintic modes of action and mechanisms of resistance.

Detection, occurrence, and fate of emerging contaminants in agricultural environments (2020)

A review of 79 papers published in 2019 is presented. The topics ranged from detailed descriptions of analytical methods, to fate and occurrence studies, to ecological effects and sampling techniques for a wide variety of emerging contaminants likely to occur in agricultural environments. New methods and studies on veterinary pharmaceuticals, antibiotics, anthelmintics, and engineered nanomaterials in agricultural environments continue to expand our knowledge base on the occurrence and potential impacts of these compounds. This review is divided into the following sections: Introduction, Analytical Methods, Antibiotics in Agroecosystems, Pharmaceutical Fate and Occurrence, Anthelmintics and Engineered Nanomaterials. PRACTITIONER POINTS: New research describes innovative new techniques for emerging contaminant detection in agricultural settings Newer classes of contaminants include human and veterinary pharmaceuticals Research in nanomaterials show that these also occur in agricultural environments and will likely be topics of future work.

The Identification of Metabolites and Effects of Albendazole in Alfalfa (Medicago sativa)

Albendazole (ABZ), a widely used anthelmintic drug, enters the environment mainly via livestock excrements. To evaluate the environmental impact of ABZ, the knowledge of its uptake, effects and metabolism in all non-target organisms, including plants, is essential. The present study was designed to identify the metabolic pathway of ABZ and to test potential ABZ phytotoxicity in fodder plant alfalfa, with seeds and in vitro regenerants used for these purposes. Alfalfa was chosen, as it may meet manure from ABZ-treated animals in pastures and fields. Alfalfa is often used as a feed of livestock, which might already be infected with helminths. The obtained results showed that ABZ did not inhibit alfalfa seed germination and germ growth, but evoked stress and a toxic effect in alfalfa regenerants. Alfalfa regenerants were able to uptake ABZ and transform it into 21 metabolites. UHPLC-MS/MS analysis revealed three new ABZ metabolites that have not been described yet. The discovery of the parent compound ABZ together with the anthelmintically active and instable metabolites in alfalfa leaves shows that the contact of fodder plants with ABZ-containing manure might represent not only a danger for herbivorous invertebrates, but also may cause the development of ABZ resistance in helminths.

The Uptake of Ivermectin and Its Effects in Roots, Leaves and Seeds of Soybean (Glycine max)

In recent years interest has grown in the occurrence and the effects of pharmaceuticals in the environment. The aim of this work is to evaluate the risk of fertilizing crops with manure from livestock treated with anthelmintics. The present study was designed to follow the fate of the commonly used anthelmintic drug, ivermectin (IVM) and its metabolites in soybeans (Glycine max (L.) Merr.), a plant that is grown and consumed world-wide for its high content of nutritional and health-beneficial substances. In vitro plantlets and soybean plants, cultivated in a greenhouse, were used for this purpose. Our results showed the uptake of IVM and its translocation to the leaves, but not in the pods and the beans. Four IVM metabolites were detected in the roots, and one in the leaves. IVM exposure decreased slightly the number and weight of the beans and induced changes in the activities of antioxidant enzymes. In addition, the presence of IVM affected the proportion of individual isoflavones and reduced the content of isoflavones aglycones, which might decrease the therapeutic value of soybeans. Fertilization of soybean fields with manure from IVM-treated animals appears to be safe for humans, due to the absence of IVM in beans, the food part of plants. On the other hand, it could negatively affect soybean plants and herbivorous invertebrates.

Evaluation of anthelmintic drugs against egg development of rumen flukes recovered from cattle raised in the humid tropics of Mexico

Paramphistomosis is a parasitic disease endemic in ruminants nearly worldwide. In the present study, an in vitro screening of the main anthelmintics used in Mexico was carried out to determine the mean lethal dose for rumen fluke eggs from cattle in a humid, warm region. Rumen flukes were obtained from cattle slaughtered in the states of Tabasco and Chiapas in Mexico. Eggs were collected using a 37-μm sieve and quantified. Then, an in vitro incubation study was performed: 100 eggs were placed into the wells of polystyrene microtiter plates. Anthelmintic products were tested on the eggs at concentrations ranging from 0.0015 to 3.0 mg/ml for rafoxanide, 0.0025 to 10.20 mg/ml for nitroxinil and 0.0015 to 3 mg/ml for closantel to determine the median lethal dose (LD50) and maximum lethal dose (LD99). A control group (water) was included in each plate. Three different species of rumen flukes (Calicophoron brothriophoron, Calicophoron clavula and Paramphistomum cervi) belonging to five isolates were identified. Nitroxinil had the highest efficacy against rumen fluke eggs, with an LD50 of 0.11 to 65 μg/ml, whereas rafoxanide showed the lowest efficacy with an LD50 ranging from 500 to 1713 μg/ml. Closantel showed high variability in the LD50 among the different analysed isolates (17 to 122 μg/ml). The evaluated flukicidal drugs presented differential efficacy against the development of rumen fluke eggs. The efficacy of the drugs will vary depending on the geographical area of origin of the animals.

Pharmacokinetic comparison of six anthelmintics in sheep, goats, and cattle

This study was initiated to determine whether a comparative pharmacokinetic (PK) approach could be used to expand the pool of approved anthelmintics for minor ruminant species. Accordingly, the PK profiles of six anthelmintics (levamisole, albendazole, fenbendazole, moxidectin, doramectin, and ivermectin) in sheep, goats, and cattle were determined. The PK values determined for each anthelmintic included T_max , T_last , C_max , AUC, AUC/dose, and C_max /dose. The results of this study demonstrate that a comparative PK approach does not show commonality in the way these six anthelmintics are individually processed by these three ruminants. While some drugs demonstrated identical PK profiles between sheep and goats, none of these drugs demonstrated PK profiles in sheep and goats comparable to the PK profiles found in cattle. The results from this study suggest drug approval across these three ruminants is not a viable concept. However, the resulting PK profiles for each combination of drug and ruminant species represents a new dataset that can be used to support the US FDA Center for Veterinary Medicine's Minor Use/Minor Species indexing process for drug approvals in minor species such as sheep and goats.

Sub-lethal doses of albendazole induce drug metabolizing enzymes and increase albendazole deactivation in Haemonchus contortus adults

The efficacy of anthelmintic therapy of farm animals rapidly decreases due to drug resistance development in helminths. In resistant isolates, the increased expression and activity of drug-metabolizing enzymes (DMEs), e.g. cytochromes P450 (CYPs), UDP-glycosyltransferases (UGTs) and P-glycoprotein transporters (P-gps), in comparison to sensitive isolates have been described. However, the mechanisms and circumstances of DMEs induction are not well known. Therefore, the present study was designed to find the changes in expression of CYPs, UGTs and P-gps in adult parasitic nematodes Haemonchus contortus exposed to sub-lethal doses of the benzimidazole anthelmintic drug albendazole (ABZ) and its active metabolite ABZ-sulfoxide (ABZSO). In addition, the effect of ABZ at sub-lethal doses on the ability to deactivate ABZ during consequent treatment was studied. The results showed that contact of H. contortus adults with sub-lethal doses of ABZ and ABZSO led to a significant induction of several DMEs, particularly cyp-2, cyp-3, cyp-6, cyp-7, cyp-8, UGT10B1, UGT24C1, UGT26A2, UGT365A1, UGT366C1, UGT368B2, UGT367A1, UGT371A1, UGT372A1 and pgp-3, pgp-9.1, pgp-9.2, pgp-10. This induction led to increased formation of ABZ metabolites (especially glycosides) and their increased export from the helminths' body into the medium. The present study demonstrates for the first time that contact of H. contortus with sub-lethal doses of ABZ (e.g. during underdose treatment) improves the ability of H. contortus adults to deactivate ABZ in consequent therapy.

Anthelmintic drugs for treating ascariasis

BACKGROUND

Ascaris lumbricoides is a common infection, and mainly affects children living in low-income areas. Water and sanitation improvement, health education, and drug treatment may help break the cycle of transmission, and effective drugs will reduce morbidity.

OBJECTIVES

To compare the efficacy and safety of anthelmintic drugs (albendazole, mebendazole, ivermectin) for treating people with Ascaris infection.

SEARCH METHODS

We searched the Cochrane Infectious Disease Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, three other databases, and reference lists of included studies, without language restrictions, up to 4 July 2019.

SELECTION CRITERIA

Randomized controlled trials (RCT) that compared albendazole, mebendazole, and ivermectin in children and adults with confirmed Ascaris infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, assessed risk of bias, and extracted data from the included trials. A third review author checked the quality of data extraction. We used the Cochrane 'Risk of bias' assessment tool to determine the risk of bias in included trials. We used risk ratios (RRs) with 95% confidence intervals (CIs) to compare dichotomous outcomes in treatment and control groups. We used the fixed-effect model for studies with low heterogeneity and the random-effects model for studies with moderate to high heterogeneity. We assessed the certainty of the evidence using the GRADE approach. We used the control rate average to provide illustrative cure rates in the comparison groups.

MAIN RESULTS

We included 30 parallel-group RCTs, which enrolled 6442 participants from 17 countries across Africa, Asia, Central America and the Caribbean, and South America. Participants were from 28 days to 82 years of age, recruited from school, communities, and health facilities. Twenty studies were funded or co-funded by manufacturers, while 10 studies were independent of manufacturer funding. Twenty-two trials had a high risk of bias for one or two domains (blinding, incomplete outcome data, selective reporting). Single dose of albendazole (four trials), mebendazole (three trials) or ivermectin (one trial) was compared to placebo. Parasitological cure at 14 to 60 days was high in all the studies (illustrative cure of 93.0% in the anthelmintic group and 16.1% in the placebo group; RR 6.29, 95% CI 3.91 to 10.12; 8 trials, 1578 participants; moderate-certainty evidence). Single dose of albendazole is as effective as multiple doses of albendazole (illustrative cure of 93.2% with single dose, 94.3% with multiple doses; RR 0.98, 95% CI 0.92 to 1.05; 3 trials, 307 participants; high-certainty evidence); or as single dose of mebendazole (illustrative cure of 98.0% with albendazole, 96.9% with mebendazole; RR 1.01, 95% CI 1.00 to 1.02; 6 trials, 2131 participants; high-certainty evidence). Studies did not detect a difference between a single dose of albendazole and a single dose of ivermectin (cure rates of 87.8% with albendazole, 90.2% with ivermectin; RR 0.99, 95% CI 0.91 to 1.08; 3 trials, 519 participants; moderate-certainty evidence). Across all the studies, failure after single dose of albendazole ranged from 0.0% to 30.3%, mebendazole from 0.0% to 22.2%, and ivermectin from 0.0% to 21.6%. The egg reduction rate (ERR) measured up to 60 days after the treatment was high in all treated groups, regardless of the anthelmintic used (range 96% to 100%). It was not possible to evaluate parasitological cure by classes of infection intensity. No included trials reported complication or serious adverse events. Other adverse events were apparently similar among the compared anthelmintic groups (moderate- to low-certainty evidence). The most commonly reported other adverse events were nausea, vomiting, abdominal pain, diarrhoea, headache, and fever.

AUTHORS' CONCLUSIONS

Single-dose of albendazole, mebendazole, and ivermectin all appeared effective against Ascaris lumbricoides infection, yielding high parasitological cure and large reductions in eggs excreted, with no differences detected between them. The drugs appear to be safe to treat children and adults with confirmed Ascaris infection. There is little to choose between drugs and regimens in terms of cure or adverse events.

Detection, occurrence, and fate of emerging contaminants in agricultural environments (2019)

A review of 82 papers published in 2018 is presented. The topics ranged from detailed descriptions of analytical methods, to fate and occurrence studies, to ecological effects and sampling techniques for a wide variety of emerging contaminants likely to occur in agricultural environments. New methods and studies on veterinary pharmaceuticals, microplastics, and engineered nanomaterials in agricultural environments continue to expand our knowledge base on the occurrence and potential impacts of these compounds. This review is divided into the following sections: Introduction, Analytical Methods, Fate and Occurrence, Pharmaceutical Metabolites, Anthelmintics, Microplastics, and Engineered Nanomaterials. PRACTITIONER POINTS: New research describes innovative new techniques for emerging contaminant detection in agricultural settings. Newer classes of contaminants include human and veterinary pharmaceuticals. Research in microplastics and nanomaterials shows that these also occur in agricultural environments and will likely be topics of future work.

Efficacy of herbal extracts and closantel against fenbendazole-resistant Haemonchus contortus

This study assessed the efficacy of closantel vis-à-vis herbal extracts with known anti-parasitic properties, against fenbendazole-resistant nematodes in goats maintained under a semi-intensive system of management at the University goat farm, Jabalpur. Fifty goats were randomly assigned to five groups, each comprising 10 animals, irrespective of their breed, age and sex. Each animal in Group I, II and III was orally administered with aqueous leaf extracts of neem (Azadirachta indica) at 1 g/kg body weight, sitaphal (Annona squamosa) at 1.5 g/kg body weight and tobacco (Nicotiana tabacum) at 1 g/kg body weight, respectively, whereas Group IV was an untreated control group. Each animal in Group V was orally treated with closantel at 10 mg/kg body weight. During the course of the study, all animals were maintained under an identical semi-intensive system of management. Compared to the untreated control group (Group IV), there was no conspicuous reduction in post-treatment (day 10) faecal egg counts (FEC) in animals administered with the herbal extracts (Groups I, II and III), which is suggestive of poor anti-parasitic activity. However, using the faecal egg count reduction test (FECRT), the overall efficacy of closantel was recorded as 95.64%. This supports the rotational use of closantel as a preferred choice over the benzimidazole group of anthelmintics and/or herbal extracts to meet the acute challenge of in situ development of drug-resistant gastrointestinal nematodes, especially Haemonchus contortus.

Helminths and microbes within the vertebrate gut - not all studies are created equal

The multifaceted interactions occurring between gastrointestinal (GI) parasitic helminths and the host gut microbiota are emerging as a key area of study within the broader research domain of host-pathogen relationships. Over the past few years, a wealth of investigations has demonstrated that GI helminths interact with the host gut flora, and that such interactions result in modifications of the host immune and metabolic statuses. Nevertheless, whilst selected changes in gut microbial composition are consistently observed in response to GI helminth infections across several host-parasite systems, research in this area to date is largely characterised by inconsistent findings. These discrepancies are particularly evident when data from studies of GI helminth-microbiota interactions conducted in humans from parasite-endemic regions are compared. In this review, we provide an overview of the main sources of variance that affect investigations on helminth-gut microbiota interactions in humans, and propose a series of methodological approaches that, whilst accounting for the inevitable constraints of fieldwork, are aimed at minimising confounding factors and draw biologically meaningful interpretations from highly variable datasets.

Impact of a single treatment of injectable doramectin on weight gain post weaning in beef heifers and steers in central Queensland, Australia

OBJECTIVES

To demonstrate the impact of a single drench with a label dose of injectable doramectin subsequent to weaning on the growth and performance of heifers and steers in central Queensland beef herds.

METHODS

Three studies were undertaken on recently-weaned Bos indicus-cross beef calves with ≥ 75% B. indicus content on two farms in central Queensland, just north of the Tropic of Capricorn. Farm 1 was located 50 km north and Farm 2 75 km north-west of Rockhampton. In each study, half of a group of recently-weaned beef calves were treated by random allocation with 0.2 mg/kg of injectable doramectin, and the remainder acting as untreated controls. Study 1 (Farm 1) enrolled 250 heifers, while studies 2 and 3 (Farm 2) both enrolled 200 steers and 200 heifers. The farms involved did not historically use macrocyclic lactone-based drenches on their cattle. There were varying periods of follow-up, with treated and control cattle pastured as one group throughout the study period. Worm burdens were monitored using standard faecal egg counts and larval differentiation procedures. In all studies, the worm genera present were a mix of Cooperia spp., Haemonchus spp. and Oesophagostomum spp.

RESULTS

In study 1, conducted on Farm 1 beginning 9 July 2012, doramectin-treated cattle gained an average of 0.27 kg/day while control cattle gained 0.19 kg/day over a monitoring period of 121 days (P < 0.0001). In study 2, conducted on Farm 2 beginning 28 July 2015, doramectin-treated cattle gained an average of 0.15 kg/day versus 0.145 kg/day in the control group (P = 0.44) over a 231-day study period. In study 3, conducted on Farm 2 beginning 4 August 2016, doramectin-treated steers and heifers gained an average of 0.431 and 0.402 kg/day versus 0.342 and 0.311 kg/day in the control group, respectively, over the first 91 days of the study (P < 0.0001 in both cases). The differences in average daily gain (ADG) in subsequent time periods were not statistically significant for steers or heifers. However, overall differences in ADG from day 0 remained statistically significant out to day 258, when the study ended for the heifers. By day 594, when the study ended for the steers, the difference in ADG was no longer significant.

CONCLUSION

Treatment with injectable doramectin soon after weaning resulted in improved weight gain in the 3 months after weaning in two of the three studies.

Development and Optimisation of a Multiresidue Method for the Determination of 40 Anthelmintic Compounds in Environmental Water Samples by Solid Phase Extraction (SPE) with LC-MS/MS Detection

A comprehensive multiresidue method was developed and validated for the determination of 40 anthelmintic compounds, including 13 transformation products, in surface and groundwater samples at sub nanogram per litre (ng L-1) levels. Anthelmintic residues were extracted from unfiltered water samples using polymeric divinylbenzene solid phase extraction (SPE) cartridges, and eluted with methanol: acetone (50:50, v/v). Purified extracts were concentrated, filtered and injected for UHPLC-MS/MS determination. The method recovery (at a concentration representative of realistic expected environmental water levels based on literature review) ranged from 83-113%. The method was validated, at three concentration levels, in accordance to Commission Decision 2002/657/EC and SANTE/11813/2017 guidelines. Trueness and precision, under within-laboratory reproducibility conditions, ranged from 88-114% and 1.1-19.4%, respectively. The applicability of the method was assessed in a pilot study whereby 72 different surface and groundwater samples were collected and analysed for the determination of these 40 compounds for the first time in Ireland. This is the most comprehensive method available for the investigation of the occurrence of both anthelmintic parent compounds and their transformation products in raw, unfiltered environmental waters.

Effect of cooking on the stability of veterinary drug residues in chicken eggs

The available information on drug residue stability in chicken egg is scarce. The objective of this study was to evaluate the stability of drug residues in egg under different traditional cooking procedures. Fresh eggs were spiked with different drug concentrations of albendazole (ABZ) and its albendazole sulphoxide (ABZSO) and albendazole sulphone (ABZSO₂) metabolites; flubendazole (FLBZ) and its reduced flubendazole (R-FLBZ) and hydrolyzed flubendazole (H-FLBZ) metabolites; amoxicillin (AMX); and enrofloxacin (EFX) and its ciprofloxacin (CFX) metabolite. The egg samples were cooked in different ways, namely, boiling, microwaving, and omelette making. Drug residue concentrations in egg were quantified by HPLC with UV or fluorescence detectors. ABZ and ABZSO concentrations in egg were not affected by boiling and microwaving, while the omelette processing significantly reduced these molecules. Residues of ABZSO₂ in egg were stable or increased after all cooking procedures. In contrast, FLBZ and its metabolites FLBZ-H and FLBZ-R residues in egg decreased after all treatments. The residue concentration quantified for EFX and CFX did not show significant changes after any cooking method. AMX residues were unstable, with extremely significant drug reduction after all cooking processes. Conventional methods of egg cooking cannot be considered a tool to eliminate all veterinary drug residues.