Ovicidal activity of diaryl dichalcogenides and ivermectin on Fasciola hepatica: A novel candidate for a blending-based therapeutic strategy.

Fasciolosis is a food and waterborne disease caused by Fasciola spp., representing a global health burden to various hosts, including humans and other animals. This study investigates the in vitro activity of tellurium- and selenium-containing diaryl dichalcogenides: diacetal ditelluride (LQ07), diacetal diselenide (LQ62), and diacetyl diselenide (LQ68) alone and in combination with ivermectin (IVM) against eggs of Fasciola hepatica. The eggs were exposed for 12 h with each organochalcogen (OC) (0.1 - 2 mmol l-1) and IVM (0.01 - 2 mmol l-1) following an incubation of 15 days, allowing embryonation. The inhibitory concentration of 50 % (IC50) of each OC or IVM was tested with the IC10, IC30, and IC50 of IVM or each OC, respectively. LQ07, LQ62, and LQ68, as well as IVM, demonstrated a concentration-dependent ovicidal activity. The peak ovicidal activity of 99.74 % was achieved when IVM was tested at 2.0 mmol l-1. LQ62 and LQ68 demonstrated greater ovicidal activity, having an IC50 < 0.32 mmol l-1 being 6.25-fold more toxic than IVM alone. The percentage of dead eggs was significantly higher in the IVM group (early mortality), as Se-containing OCs led to the (miracidia) embryonation of the eggs with no hatching (late mortality). Blending Se-containing OCs and IVM showed an additive effect of up to 27 % against F. hepatica eggs. The present data contribute to the potential use of blending-based therapeutic strategies to combat F. hepatica infections in eradication programs worldwide. The combinations may also act against multidrug-resistant strains, reinstating drug-based parasite control.

Histological changes of oocytes of the cattle tick Rhipicephalus microplus (Canestrini, 1888) treated with copper solutions.

Infections caused by the ectoparasite Rhipicephalus microplus can cause major health problems in cattle, including death. Tick control is regularly made using a range of acaricide products. As a consequence, tick populations have been heavily selected for drug resistance. The objective of this work was to determine the in vitro efficacy of copper chloride and sulfate (CuCl2 and CuSO4) solutions against R. microplus. The adult immersion test (AIT), which measures the egg-laying and egg-hatch effects, was used for the Cu-II solutions at 30, 60, 120, 240, 480, and 1000 mM, in triplicates. Distilled water and the combination of cypermethrin 20% and chlorpyrifos 50% were used as controls. Histological sections were performed from the ovaries of adult engorged female ticks treated with 240, 480, and 1000 mM of CuCl2 and CuSO4. We have established a histological index of the damage caused by the solutions to the tick oocytes. The overall efficacy (egg laying & egg hatch) for CuCl2 and CuSO4 was 81.3, 82.5, 89.8, 84.5, 100.0, and 100%, and 61.7, 43.4, 62.5, 93.1, 100.0, and 98.5% respectively. Smaller oocytes were found in the Cu-II groups compared to the negative control. The histological data showed a concentration-dependent degenerative lesion of oocytes, described as cytoplasmic vacuolation and nuclear disorganization. The combination of cypermethrin and chlorpyriphos showed 100% efficacy. Cu-II solutions showed in vitro efficacy against adult engorged ticks being particularly harmful to oocytes. Thus, bioactive metals could be a complementary biofriendly treatment to control R. microplus and these injuries could be responsible for preventing egg hatch, and reducing pasture contamination. Safety studies are underway demonstrating the Cu-II potential in naturally infected cattle and their persistence in the environment.

Reduction of egg reappearance period of cyathostomins in naturally infected horses after increasing doses of ivermectin in Brazil: a grim picture for sustainable parasite control.

Cyathostomins are the largest group of parasites in horses that can be controlled by ivermectin (IVM). This study aimed to run a four-dose titration trial of IVM in 28 naturally infected Thoroughbred yearlings. The local Strongyle population had been recorded to be resistant to IVM (200 µg/kg). The parasite fecal egg count (FEC) was performed to investigate the egg reappearance period (ERP) of two and five weeks (w2pt and w5pt) after IVM treatment. FEC was > 1000 on day zero for all groups. Although 100% FEC reduction was reported at w2pt for all concentrations, the FEC at w5pt revealed < 83% efficacy. This study reports the reduction of ERP using the label dose as well as 300, and 400 µg/kg (double dose) of IVM. The protocol allowed IVM to significantly suppress FEC w2pt although not eliminating adult worms, failing to guarantee an extension of its protection period over 8 weeks. Moreover, the FEC at w5pt possibly means the infection was not cleared, and worms reestablished egg laying. We raised the possibility of withdrawing IVM of control programs when the drug has less than 80% FEC reduction at w5pt.

Prevalence and risk factors of gastrointestinal helminths infection in Brazilian horses: A retrospective study of a 12-year (2008-2019) diagnostic data.

Understanding gastrointestinal parasite distribution is crucial for effective control programs in horses. This study reports the prevalence of helminth infections in horses and selected risk factors (i.e., breed, age, climate, season) by analyzing 19,276 fecal samples from the Laboratory of Veterinary Clinical Parasitology, in Curitiba, Southern Brazil. The analyses were carried out from 2008 to 2019, coming from 153 stud farms located in 60 municipalities of nine Brazilian states. The parasite prevalence was 73.3%, with 72.1% present in the adult population and 80.6% in young horses. Strongyles were present in 100% horse farms. Strongyles had a prevalence of 72.1% with a mean FEC of 453.53 (+/- 717.6). Parascaris spp. had a prevalence of 5.8% and a FEC of 17.11 (+/- 149.2). The tropical wet/monsoon climate (Am) showed the lowest FEC for strongyles and Parascaris spp. when compared to the other climates. In the logistic regression analysis, young horses exhibited 4.6 times higher odds ratio (OR) (3.9-5.5) of Parascaris spp. and 1.2 (1.1-1.4) times higher OR of strongyles egg shedding when compared to adults (P < 0.001). Summer presented a higher risk for Parascaris spp. and Strongyles eggs when compared to the other seasons (P < 0.001). Mangalarga Marchador, Criollo, and Crossbred breeds were identified with higher OR of Parascaris spp. egg shedding than Thoroughbred. The extensive prevalence of strongyles across ages, seasons, breeds, and climates alerts for the risk of clinical manifestations in equines raised on pastures designing optimal health management and parasite control strategies worldwide.

Identification of third stage larvae of strongyles and molecular diagnosis of Strongylus vulgaris in the feces of Thoroughbred horses kept in training centers in Rio de Janeiro, Brazil.

The aims of the present study were to identify strongyles in the feces of Thoroughbred horses based on larval morphology; to detect Strongylus vulgaris using molecular diagnosis and compare results to those of feces culture; and to determine the association between the presence of S. vulgaris with corresponding animal information (age range, gender, and anthelmintic use). Feces of horses kept in six Training Centers in Rio de Janeiro State, that showed the presence of ≥500 eggs per gram of feces (EPG) were subjected to strongyle identification. Of the 520 fecal samples collected, 35 had an EPG ≥ 500. After fecal culture for L3 larvae identification, DNA was extracted, subjected to PCR to amplify the ITS2 region DNA fragment of S. vulgaris, and sequenced. A total of 3500 larvae were analyzed. Most were classified as small strong (99.7%), with an emphasis on the type A subfamily of Cyathostominae. Forms of S. vulgaris only corresponded to 0.2%. In all, 25 samples showed amplified S. vulgaris DNA products and 11 showed nucleotide sequences with high sequence identity. Fecal culture and PCR results showed poor agreement (kappa = 0.105) for S. vulgaris diagnosis. Age, gender, anthelmintic use, and anthelmintic administration interval were not statistically significant. The present study showed the presence of S. vulgaris in the feces of horses kept in Rio de Janeiro Training Centers, mainly seen via PCR, which has emerged as the most effective tool for diagnosis. This study made it possible to identify strongyles that infect horses in the region, emphasizing upon the necessity for constant monitoring of the animals.

Geographic expansion of Fasciola hepatica (Linnaeus, 1758) due to changes in land use and cover in Brazil.

Fasciolosis is caused by parasites of the genus Fasciola, affecting animals and humans worldwide. In South America, the disease is a result of infection with Fasciola hepatica and although animal infections are more frequently reported, the full extent of the impact on human health due to underdiagnosis remains uncertain. This study analyzed changes in land use and the distribution of F. hepatica in bovine livers in Brazil over 18 years. Data on land use and land cover were collected from the Mapbiomas Project. Data on 414,481,963 slaughtered cattle and condemned livers due to F. hepatica infection were obtained from 4,433 municipalities. Joinpoint analysis was used to study the time series, and the Susceptible-Infected-Recovered (SIR) model was utilized to explore the behavior of F. hepatica infection. In the North, pasture areas significantly increased (P = 0.000001), while forested areas decreased (P = 0.000001). The midwestern and northern regions concentrated the highest number (>290 million) of cattle slaughtered in Brazil. More than 2 million bovine livers were infected by F. hepatica. The infected cattle originated from 194 municipalities in 2002, increasing to 747 in 2020. We consider that the changes in land use and intense cattle transportation may have caused the expansion of F. hepatica. The SIR model analyzed the spread of the disease looking at all six biomes: Caatinga, Amazon Forest, Cerrado, Pantanal, Atlantic Forest, and Pampa. Moreover, this infection not only threatens the health of animals but is also a major concern to biodiversity and vulnerable human communities in South America. Emblematic biomes such as the Amazon basin already face challenges with logging, desertification, and loss of biodiversity. Therefore, strategies for mitigating infection should include controlling illegal pasture areas, establishing health inspections of animal transport, quarantine of newly arrived animals, and livestock zoning, as well as clear One Health policies.

First microscopic and molecular parasitological survey of Strongylus vulgaris in Brazilian ponies.

The frequency of gastrointestinal parasites with an emphasis on Strongylus vulgaris was investigated among the Brazilian Pony breed kept on farms in the municipality of Teresópolis, state of Rio de Janeiro. Fecal samples were collected in three stud farms: A (n= 22 animals), B (n= 3), and C (n= 2). Fecal samples were subjected to the quantitative Mini-FLOTAC technique, using three different solutions, and to qualitative techniques. The parasite prevalence was found to be 81.4%. Eggs from strongylids were identified in 74% of the ponies. Eggs of Parascaris spp. were detected in 22.7% of the animals, which were all females of farm A. At this locality, mares were kept with their foals in fenced paddocks all the time. The NaCl solution of d = 1.200 g/ml was generally the one that presented the highest frequency of diagnosis of nematode eggs and the highest mean of fecal eggs per gram. The fecal samples were also subjected to the polymerase chain reaction for amplification of DNA from the ITS2 region for Strongylus vulgaris. Twelve samples presented nucleotide sequences for S. vulgaris. In the end, this study revealed the high frequency (96.3%) of S. vulgaris among ponies on farms in Teresópolis, Rio de Janeiro, Brazil.

A systematic review of honey bee (Apis mellifera, Linnaeus, 1758) infections and available treatment options.

BACKGROUND: Honey bees and honeycomb bees are very valuable for wild flowering plants and economically important crops due to their role as pollinators. However, these insects confront many disease threats (viruses, parasites, bacteria and fungi) and large pesticide concentrations in the environment. Varroa destructor is the most prevalent disease that has had the most negative effects on the fitness and survival of different honey bees (Apis mellifera and A. cerana). Moreover, honey bees are social insects and this ectoparasite can be easily transmitted within and across bee colonies. OBJECTIVE: This review aims to provide a survey of the diversity and distribution of important bee infections and possible management and treatment options, so that honey bee colony health can be maintained. METHODS: We used PRISMA guidelines throughout article selection, published between January 1960 and December 2020. PubMed, Google Scholar, Scopus, Cochrane Library, Web of Science and Ovid databases were searched. RESULTS: We have collected 132 articles and retained 106 articles for this study. The data obtained revealed that V. destructor and Nosema spp. were found to be the major pathogens of honey bees worldwide. The impact of these infections can result in the incapacity of forager bees to fly, disorientation, paralysis, and death of many individuals in the colony. We find that both hygienic and chemical pest management strategies must be implemented to prevent, reduce the parasite loads and transmission of pathogens. The use of an effective miticide (fluvalinate-tau, coumaphos and amitraz) now seems to be an essential and common practice required to minimise the impact of Varroa mites and other pathogens on bee colonies. New, alternative biofriendly control methods, are on the rise, and could be critical for maintaining honey bee hive health and improving honey productivity. CONCLUSIONS: We suggest that critical health control methods be adopted globally and that an international monitoring system be implemented to determine honey bee colony safety, regularly identify parasite prevalence, as well as potential risk factors, so that the impact of pathogens on bee health can be recognised and quantified on a global scale.

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 200­500 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.

l-carvone decreases breast cancer cells adhesion, migration, and invasion by suppressing FAK activation.

Breast cancer is one of the most common types of cancer in the world and current therapeutic strategies present severe drawbacks. l-carvone (CRV), a monoterpene found in Mentha spicata (spearmint), has been reported to have potent anti-inflammatory activity. Here, we examined the role of CRV in breast cancer cell adhesion, migration and invasion in vitro and how this component could suppress the growth of Ehrlich carcinoma-bearing mice. In vivo, treatment with CRV significantly decreased tumor growth, increased tumor necrosis area, and reduced the expression of VEGF and HIF-1α in Ehrlich carcinoma-bearing mice. Furthermore, the anticancer efficacy of CRV was similar to currently used chemotherapy (Methotrexate), and the combination of CRV with MTX potentiated the chemotherapy effects. Further mechanistic investigation in vitro revealed that CRV modulates the interaction of breast cancer cells with the extracellular matrix (ECM) by disrupting focal adhesion, which was shown by scanning electron microscopy (SEM) and immunofluorescence. Moreover, CRV caused a decrease in ß1-integrin expression and inhibited focal adhesion kinase (FAK) activation. FAK is one of the most important downstream activators of several metastatic processes, including MMP-2 mediated invasion and HIF-1α/VEGF angiogenesis stimulus, both of which were found to be reduced in MDA-MB-231 cells exposed to CRV. Our results provide new insight about targeting ß1-integrin/FAK signaling pathway with CRV, which could be a new potential agent in the treatment of breast cancer.

A Systematic Review of Apicomplexa Looking into Epigenetic Pathways and the Opportunity for Novel Therapies.

Interest in host epigenetic changes during apicomplexan infections increased in the last decade, mainly due to the emergence of new therapies directed to these alterations. This review aims to carry out a bibliometric analysis of the publications related to host epigenetic changes during apicomplexan infections and to summarize the main studied pathways in this context, pointing out those that represent putative drug targets. We used four databases for the article search. After screening, 116 studies were included. The bibliometric analysis revealed that the USA and China had the highest number of relevant publications. The evaluation of the selected studies revealed that Toxoplasma gondii was considered in most of the studies, non-coding RNA was the most frequently reported epigenetic event, and host defense was the most explored pathway. These findings were reinforced by an analysis of the co-occurrence of keywords. Even though we present putative targets for repurposing epidrugs and ncRNA-based drugs in apicomplexan infections, we understand that more detailed knowledge of the hosts' epigenetic pathways is still needed before establishing a definitive drug target.

Genome-wide association study in thoroughbred horses naturally infected with cyathostomins.

Cyathostomins are considered one of the most important parasites of horses. A group of horses within a herd can be responsible for eliminating the majority of parasite eggs. This phenotype might be explained by genetic factors. This study aimed to identify genomic regions associated with fecal egg count (FEC) and hematological parameters by performing a genomic-wide association study (GWAS) in Thoroughbred horses naturally infected with cyathostomins. Packed cell volume (PCV), differential leukocyte, and FEC were determined from 90 horses. All animals were genotyped using the Illumina Equine 70 K BeadChip panel containing 65,157 SNP markers. The five genomic windows that have explained the highest percentage of the additive genetic variance of a specific trait (top 5) were further explored to identify candidate genes. A total of 33, 21, 30, 21, and 19 genes were identified for FEC, PCV, eosinophils, neutrophils, and lymphocyte count, respectively. The top 5 marker regions explained 2.86, 2.56, 2.73, 2.33, and 2.37% of the additive genetic variation of FEC, PCV, eosinophils, neutrophils, and lymphocytes count, respectively. This is the first study correlating phenotypic horse health traits to GWAS analysis, which may be used for animal breeding activities, reducing losses due to parasite infections.

Allium sativum extract against free-living larvae of Rhipicephalus microplus: a potential environmental biocontrol.

The infestation of Rhipicephalus microplus (Acari: Ixodidae) (Canestrini, 1887) represents a significant health problem for cattle. Up until today, no consistent control has been recommended for the free-living larval stage of R. microplus. The objective of the present study was to determine the larvicidal effect of an Allium sativum (garlic) aqueous extract against R. microplus using the larval package test, LPT. Tick larvae were obtained from adult female ticks from naturally infected animals, and 200 larvae were exposed to each A. sativum extract concentration (5, 7, 10, 16, 25, and 50%). All garlic groups received the extract in three different volumes (2, 5, and 7 ml) to determine the levels of humidity that would affect the free-living stage. Larvae from the control group were treated with distilled water and the positive control used cypermethrin in a 5-ml volume. Live and dead larvae were determined after 24 h of exposure. There was a significant statistical difference (P = 0.041) at 5% between 2 and 5 ml and between 7 and 10% of the extract using 2 ml (P = 0.034). There was a significant larvicidal activity of 100% mortality for the 16, 25, and 50% concentrations for all volumes. We observed a clear concentration-dependent effect for the extracts with a correlation coefficient of R2 > 0.92. The lethal concentration of 50% (LC50) was 13.6, 9.8, and 7.6% for the 2, 5, and 7 ml. The present A. sativum solutions may be considered a viable biofriendly alternative to reduce the number of the free-living larval stage of R. microplus on pasture and the consequent reduction of cattle infestation due to its high larval mortality.

Comparative study of antioxidant properties of the extracts of Polygonum acre H.B.K

SUMMARY Aims: This study aimed to characterize and compare the antioxidative potential of extracts obtained by infusion, decoction, tincture, aqueous extraction, and hydro-ethanolic maceration from the aerial parts of Polygonum acre H.B.K., which has been traditionally used in herbal preparations, for different purposes. The therapeutic benefits are attributed to phenolic compounds and their antioxidant properties. Methods: All extracts were characterized considering their quantitative content of the total phenolics, flavonoids, condensed and, hydrolysable tannins, by colori-metric methods. EHW-PA was selected for HPLC analysis as it showed a higher yield (10.58 % w/m) and a phenolic content > 200 mg GAE/g dry extract. The phenolic profile showed a chromatogram with 20 peaks, and the presence of gallic acid, rutin, and quercetin was verified by comparison with the retention times of standard compounds. The antioxidant activities were determined by ABTS capture test, ferric reducing antioxidant power test (FRAP), and the superoxide anion scavenging test. Results: Tinctures showed a higher average content of phenolic compounds, present mainly as flavonoid content. A significant correlation coefficient was observed between the total phenolic content and its antioxidant activity, determining by ABTS and FRAP assays. Differently, a low to moderate correlation between the flavonoid content and antioxidant activity was verified. Conclusion: This study reinforces the ethnopharmacological relevance of the Polygonum genus and could contribute to the scientific basis for the use of P. acre preparations.

Objetivos: Este estudio tuvo como objetivo caracterizar y comparar el potencial antioxidante de extractos obtenidos por infusión, decocción, tintura, extracción acuosa e hidroetanólica de las partes aéreas de Polygonum acre H.B.K., que se ha utilizado tradicionalmente en preparaciones a base de hierbas, para diferentes fines. Los beneficios terapéuticos se atribuyen a los compuestos fenólicos y sus propiedades antioxidantes. Métodos: Todos los extractos se caracterizaron considerando su contenido cuantitativo de fenólicos totales, flavonoides, taninos condensados e hidrolizables, por métodos colorimétricos. Se seleccionó EHW-PA para el análisis de HPLC ya que mostró un rendimiento más alto (10,58% m/m) y un contenido fenólico > 200 mg GAE/g de extracto seco. El perfil fenólico mostró un cromatograma con 20 picos y se verificó la presencia de ácido gálico, rutina y quercetina por comparación con los tiempos de retención de los compuestos estándar. Las actividades antioxidantes se determinaron mediante la prueba de captura ABTS, la prueba del poder antioxidante reductor férrico (FRAP) y la prueba de eliminación del anión superóxido. Resultados: Las tinturas mostraron un mayor contenido promedio de compuestos fenólicos, presentes principalmente como contenido de flavonoides. Se observó un coeficiente de correlación significativo entre el contenido fenólico total y su actividad antioxidante, determinado por ensayos ABTS y FRAP. De manera diferente, se verificó una correlación de baja a moderada entre el contenido de flavonoides y la actividad antioxidante. Conclusión: Este estudio refuerza la relevancia etnofarma-cológica del género Polygonum y podría contribuir a la base científica para el uso de preparaciones de P. acre.

Objetivos: O presente estudo teve como objetivo caracterizar e comparar o potencial antioxidante de extratos obtidos por infusão, decocção, tintura, extração aquosa e maceração hidroetanólica da parte aérea de Polygonum acre H.B.K., tradicional- mente utilizado em preparações fitoterápicas, para diversos fins. Os benefícios terapêuticos são atribuídos aos compostos fenólicos e suas propriedades antioxidantes. Métodos: Todos os extratos foram caracterizados quanto ao teor quantitativo de fenólicos totais, flavonoides, taninos condensados e hidrolisáveis, por métodos colorimétricos. O EHW-PA foi selecionado para análise por HPLC por apresentar maior rendimento (10,58% m/v) e conteúdo fenólico > 200 mg GAE/g de extrato seco. O perfil fenólico apresentou cromatograma com 20 picos, e a presença de ácido gálico, rutina e quercetina foi verificada pela comparação com os tempos de retenção dos compostos padrão. As atividades antioxidantes foram determinadas pelo teste de captura do radical ABTS, ensaio do potencial antioxidante por redução férrica (FRAP) e teste de desativação do ânion superóxido. Resultados: As tinturas apresentaram maior teor médio de compostos fenólicos, presentes, principalmente, na forma de flavonoides. Foi observado um coeficiente de correlação significativo entre o conteúdo fenólico total e sua atividade antioxidante, determinado pelos ensaios de ABTS e FRAP. Diferentemente, verificou-se uma correlação baixa a moderada entre o conteúdo de flavonoides e a atividade antioxidante. Conclusão: Este estudo reforça a relevância etnofarmacológica do gênero Polygonum e pode contribuir para a fundamentação científica do uso de preparações de P. acre.

Acaricidal effect of major compounds to control Rhipicephalus microplus (Canestrini, 1887) in dairy cows and possible alternatives for reversing multidrug resistance.

Tick control represent a great challenge to animal health. The objective of this study was to evaluate the efficacy of acaricidal compounds against Rhipicephalus microplus from dairy cattle systems in Paraná State, Brazil. Six farms (PR1-PR6) were selected, where anti-tick products were applied at fixed intervals. Two other farms that adopted alternative protocols; target selective treatment (PRS), and individual-based agroecological protocol (PRA) were also included in the trial. Fully engorged R. microplus were collected for the in vitro adult immersion test (AIT), and the egg hatch test (EHT) in all eight populations. The larval packet test (LPT) was used on PR6 and PRA tick populations. The treatment groups were composed of G1: dichlorvos 45% plus cypermethrin 5%, G2: deltamethrin 2.5%, G3: cypermethrin 15%, chlorpyriphos 25%, plus citronellal 1%, and G4: amitraz 12.5%. The efficacy at PR1 to PR6 revealed that G3 and G4 achieved moderate to high efficacy, from 75.0 to 100.0% and 73 to 98%, respectively. In the LPT, the efficacy at PR6 was 76.0, 67.0, 93.0 and 30.6%, while PRA presented 100.0, 100.0, 100.0, and 54.0%, for G1, G2, G3 and G4, respectively. Sustainable parasite control strategies are discussed.

Macrocyclic lactone resistance in nematodes of cattle in Brazil: Blame it to the ticks!

Strategic helminth control in adult cattle would hardly impose sufficient selection pressure to parasite populations but reports of resistance against macrocyclic lactone (ML) based-products have been confirmed worldwide. The objective of this study was to evaluate the scientific literature of ML resistance (< 90.0% efficiency) in helminths of cattle from 2001 (the first report) to 2020 in Brazil. Additional to the data, we studied the correlation of parasite control practices based on a questionnaire given to 32 farmers. The search returned 246 reports and 21 full articles were selected. From these, a Wordcloud and a Keyword Co-occurrence Network graph were created. The published data revealed that most of the studies (19/21) reported multi-species (Cooperia spp., Haemonchus sp., Oesophagostomum radiatum, Trichostrongylus sp.) resistance to ML. None of the reports described the treatment frequency in the tested farms. As for the questionnaire, the majority of farmers (> 70.0%) responded that they rotate products after treatment, animals are treated monthly or biweekly (58.0%), treatments are based on visual evaluation (coat condition, ectoparasite infestation), and that in 94.0% of the times farmers treat all animals. Moreover, farmers use ML in association with potent acaricides (cypermethrin, chlorpyriphos, fluazuron) in more than 90.0% of the times (15/16). It was observed that this regimen was used to prevent and control the cattle-tick Rhipicephalus microplus (90.0%) and the horn-fly, Haematobia irritans (30.0%) infestations. We conclude that the most important factor for nematode resistance was the high level of ML exposure of up to 16 times/year, in combination with acaricides to control ticks and to a lesser extent to control horn-flies. Therefore, selection of helminth populations in cattle in Brazil can be considered secondary to ectoparasite control. The present analysis is critical, as one the most widespread recommendations to avoid drug resistance is to reduce the use of long-acting compounds, due to their extended persistent periods, increasing parasite selection. Moreover, a more serious attitude must be taken regarding parasite control strategies for livestock, reinforcing that health protocols should be based on single acaricidal products whenever possible. Complementary, selective evaluations based on transient threshold population abundance must be enforced to reduce treatment frequency, reducing parasite selection and animal distress.

Suppressive treatment with monepantel and the fast selection for phenotypically resistant trichostrongylids of sheep.

Gastrointestinal parasite control has been a major challenge to livestock due to the failure of anthelmintic treatments. Monepantel (MNT) was introduced in 2009 as an alternative treatment option showing a new mechanism of action against nematode parasites. To study the response of MNT in a suppressive regime, 45-Suffolk and White Dorper naturally infected sheep were divided into one of three groups, G1: control ­ with no treatment, G2: MNT at 2.5 mg kg−1 live weight (LW) PO every 30 days, and G3: MNT at 4.0 mg kgLW−1 PO every 30 days for 6 months. Every 15 days, the animals were individually weighed (body weight, BW) and checked for Famacha (FMC) and body condition score (BCS). The efficacy of MNT was evaluated weekly by fecal egg count (FEC) every month. FEC showed >97% efficacy at the start of the experiment, revealing a significant reduction for G2 (28%) and G3 (39%) in the following months. There was no treatment, BW or BCS effect between treatments; however, there was a period (P < 0.0001) and a treatment vs period interaction (P < 0.0001) for BW. The data revealed that MNT at a therapeutic and suppressive dose had a non-linear polynomial efficacy regression (R2) of 0.988 and 0.992, respectively. This original experiment demonstrates how short-interval and suppressive MNT treatments would rapidly select Haemonchus contortus, showing a fast susceptible-resistance phenotypic population replacement. Therefore, it is suggested that MNT might be carefully used in parasite control programmes alongside other management strategies (i.e. FMC, BCS) to reduce treatment frequency and the selection process for resistance.

In vitro anthelmintic activity of an aqueous extract of Glycyrrhiza glabra and of glycyrrhetinic acid against gastrointestinal nematodes of small ruminants.

This study evaluated the in vitro anthelmintic activity of a liquorice (Glycyrrhiza glabra) root aqueous extract and of glycyrrhetinic acid at 30, 10, 5, 1, and 0.5 mg/mL against sheep gastrointestinal nematodes (GINs), using the egg hatch test (EHT), the larval development test (LDT), and the larval migration inhibition test (LMIT). The compounds were applied on a mixture of GIN eggs and larvae, mainly Trichostrongylus spp. and Teladorsagia/Ostertagia spp. Cytotoxicity assays were also performed. In the EHT, both candidates showed significant concentration-dependent efficacy and were significantly more effective (p < 0.001) at the highest concentrations (30 and 10 mg/mL) than the lowest ones. In the LDT, only G. glabra showed a concentration-dependent effect (R2 = 0.924), but glycyrrhetinic acid (R2 = 0.910) had significantly higher efficacy than G. glabra root extract. Moreover, the efficacy of glycyrrhetinic acid at 30, 10, and 5 mg/mL was significantly higher (p < 0.001) than at lower concentrations. In the LMIT, G. glabra showed concentration-dependent efficacy (R2 = 0.971), while considerably reduced efficacy was observed for glycyrrhetinic acid (R2 = 0.855) at the lowest concentrations. These data suggest that the two compounds may have different mechanisms of action. In the LMIT, the 50% lethal concentration (LC50) of glycyrrhetinic acid (~5.12 mg/mL) was > 2.0-fold lower when compared to G. glabra (12.25 mg/mL). Analysis and previous findings indicated low toxicity for both compounds. The results obtained encourage in vivo studies aimed at evaluating the potential use of the tested compounds as natural de-wormers in ruminants.

TITLE: Activité anthelminthique in vitro d'un extrait aqueux de Glycyrrhiza glabra et de l'acide glycyrrhétinique contre les nématodes gastro-intestinaux des petits ruminants. ABSTRACT: Cette étude a évalué l'activité anthelminthique in vitro d'un extrait aqueux de racine de réglisse (Glycyrrhiza glabra) et de l'acide glycyrrhétinique à 30, 10, 5, 1 et 0,5 mg/mL contre les nématodes gastro-intestinaux (NGI) du mouton, en utilisant le test d'éclosion des œufs (TEO), le test de développement larvaire (TDL) et le test d'inhibition de la migration larvaire (TIML). Les composés ont été appliqués sur un mélange d'œufs et de larves de NGI, principalement Trichostrongylus spp. et Teladorsagia/Ostertagia spp. Des tests de cytotoxicité ont également été effectués. Dans le TEO, les deux candidats ont montré une efficacité concentration-dépendante significative et ont été significativement plus efficaces (p < 0,001) aux concentrations les plus élevées (30 et 10 mg/mL) qu'aux plus faibles. Dans le TDL, seul G. glabra a montré un effet concentration-dépendant (R2 = 0,924), mais l'acide glycyrrhétinique (R2 = 0,910) avait une efficacité significativement plus élevée que l'extrait de racine de G. glabra. De plus, l'efficacité de l'acide glycyrrhétinique à 30, 10 et 5 mg/mL était significativement plus élevée (P < 0,001) qu'à des concentrations plus faibles. Dans le TIML, G. glabra a montré une efficacité concentration-dépendante (R2 = 0,971), tandis qu'une forte réduction d'efficacité a été observée pour l'acide glycyrrhétinique (R2 = 0,855) aux concentrations les plus faibles. Ces données peuvent suggérer que les deux composés peuvent avoir des mécanismes d'action différents. Dans le TIML, la concentration létale à 50% (CL50) de l'acide glycyrrhétinique (~ 5,12 mg/mL) était > 2,0 fois inférieure à celle de G. glabra (12,25 mg/mL). L'analyse et les résultats précédents ont indiqué une faible toxicité pour les deux composés. Les résultats obtenus encouragent les études in vivo visant à évaluer l'utilisation potentielle des composés testés ici comme anthelminthique naturels chez les ruminants.

Cyathostomin fecal egg count and milk quality in dairy donkeys.

This study was performed to assess the possible relationship between gastrointestinal strongylid infections and milk quantity and quality in donkeys used for milk production. Individual fecal and milk samples were collected from 16 multiparous lactating jennies of Amiatina breed at their 6th month of lactation. Statistical analysis was carried out between strongylid eggs per gram of faeces (EPG) and milk parameters. All animals were found to shed cyathostomin eggs, with EPG ranging from 150 to 1900. A higher milk production was observed in animals showing an EPG< 250, but this result was statistically not significant. Conversely, significant higher concentrations of milk urea and pH values, and lower concentrations of milk lactose, were observed in jennies with an EPG >1000. In conclusion, results from this study suggest that cyathostomin EPG values > 1000 may affect milk quality in dairy donkeys. Considering the novelty of these findings, more data needs to be collected to determine EPG thresholds to be used as a good marker for parasite infections influencing milk performance and quality in donkeys.