Coccidiostats and Poultry: A Comprehensive Review and Current Legislation

A step forward to revolutionize the eimeriosis controlling strategies in cattle by using traditional medication

More than 10 species of Eimeria is found in cattle but Eimeria zuernii is one of the most pathogenic protozoan parasites affecting the global livestock industry. At the herd level, E. zuernii can cause illness in 10-80% of animals and reduce gross margins by 8-9%, leading to estimated annual losses of $731 million. This review highlights the economic impact, prevalence, and current control methods for E. zuernii infections, as well as the challenges associated with treatment and the development of alternative control methods. In the past two decades, 22 studies have examined synthetic drugs for managing eimeriosis in cattle. Various anticoccidial drugs (AcDs; Amprolium, decoquinate, ionophores, monensin, lasalocid, toltrazuril etc) have been used, but the efficacy of these drugs is no more consistent. Because of this, E. zuernii develops resistance to some of these anticoccidials. This trend highlights the urgent need for alternative treatments. The medicinal plants being enriched with various phytochemicals like flavonoids, tannins, alkaloids, terpenes etc have been reported as potential anticoccidial, anthelmintic and antimicrobial efficacy against the different parasites including Eimeria species in chicken, pig and rabbits. However, this review suggests the research community to treat the E. zuernii with a plant based medication (oils and extracts). This review critically emphasizes the need to acknowledge the significant role of medicinal plants in controlling eimeriosis and also the large-scale trials or standardization of plant-based therapies is required. By incorporating plant-based remedies into integrated treatment strategies alongside synthetic drugs and improved sanitation practices, we can effectively minimize financial losses and safeguard livestock health.

Mechanisms of Mitochondria-Mediated Apoptosis During Eimeria tenella Infection

Coccidiosis in chickens is a parasitic disease caused by Eimeria species, resulting in significant economic losses to the poultry industry. Among these species, Eimeria tenella is considered the most virulent pathogen, with its infection strongly associated with the apoptotic response of host cells. Eimeria tenella modulates host cell apoptosis in a stage-specific manner, suppressing apoptosis in the early phase to promote its intracellular development and triggering apoptosis in later stages to facilitate parasite egress and disease progression. This study established an in vitro infection model using 60 fifteen-day-old chick embryo cecal epithelial cells and infecting the cells with Eimeria tenella sporozoites at a 1:1 ratio of host cells to sporozoites. The aim was to examine the relationship between parasitic infection and the apoptotic response of host cells in the chick embryo cecal epithelial cells infected with E. tenella. The roles of the mitochondrial permeability transition pore (MPTP) and cytochrome c in intrinsic apoptosis were examined through the application of cyclosporine A (CsA), N, N, N', N'-tetramethyl-1,4-phenylenediamine (TMPD), and ascorbate (Asc). TUNEL staining, ELISA, and flow cytometry were performed to evaluate apoptotic rates. CsA, TMPD, and Asc significantly (p < 0.01) decreased cytochrome c release, caspase-9 activation, and apoptotic rates from 24 to 120 h post-E. tenella infection. These findings highlight the significance of cytochrome c-mediated, mitochondria-dependent apoptotic pathways in parasitized chick embryo cecal epithelial cells.

Antibiotics/coccidiostat exposure induces gut-brain axis remodeling for Akt/mTOR activation and BDNF-mediated neuroprotection in APEC-infected turkeys

The poultry industry relies extensively on antibiotics and coccidiostats as essential tools for disease management and productivity enhancement. However, increasing concerns about antimicrobial resistance (AMR) and the toxicological safety of these substances have prompted a deeper examination of their broader impacts on animal and human health. This study investigates the toxicological effects of antibiotics and coccidiostats on the gut-brain axis and microbiota in turkeys, with a particular focus on molecular mechanisms that may influence neurochemical and inflammatory responses. Our findings reveal that enrofloxacin exposure leads to the upregulation of BDNF, suggesting a neuroprotective effect, while monensin treatment significantly increased eEF2 kinase expression, indicative enhanced neuronal activity. In turkeys infected with Avian Pathogenic Escherichia coli (APEC), early administration of doxycycline and monensin significantly upregulated the mTOR/BDNF and Akt/mTOR pathways, along with elevated histamine levels, underscoring their role in inflammatory responses modulation. However, treatments administered at 50 days post-hatch did not significantly alter protein levels, though both enrofloxacin and monensin increased serotonin and dopamine levels, suggesting potential neurotoxicological impacts on mood and cognitive functions. These results highlight the complex interactions between antibiotic use, gut microbiota alterations, and neurochemical pathways, with toxicological implications for environmental pollution and public health. This research provides critical insights into the potential toxic effects of prolonged antibiotic and coccidiostat exposure in poultry production, emphasizing the need for responsible use to mitigate risks to ecosystems and human health.

Benzoic Acid, Enterococcus faecium, and Essential Oil Complexes Improve Ovarian and Intestinal Health via Modulating Gut Microbiota in Laying Hens Challenged with Clostridium perfringens and Coccidia

Intestinal disease is becoming increasingly prevalent in poultry production; however, the effect of BEC in laying hens challenged with C. perfringens and coccidia is limited. This study aimed to investigate the effects of dietary supplementation with BEC on intestinal and ovarian health in laying hens challenged with C. perfringens and coccidia. A total of 80 Lohmann gray hens (35 weeks) were randomly assigned to two dietary groups supplemented with BEC (0 or 1000 mg/kg). Each group contained 40 replicates, with one bird each (one hen per cage). During the sixth week of the trial, half of the laying hens in each group (n = 20) were administered 40 mL C. perfringens (2.5 × 1010 CFU/mL) and 0.15 mL coccidia (55,000 sporangia/mL), while the other half (n = 20) were administered 40 mL phosphate-buffered saline (PBS). The results indicated that those challenged with C. perfringens and coccidia had severely damaged jejunal and ovarian histopathological morphology, increased oxidative damage, decreased cecal acetic acid and butyric acid content (p < 0.05), and resulted in lower gut microbial richness and diversity. The diet of 1000 mg/kg BEC reduced the jejunal and ovarian pathological damage and oxidative damage, increased short-chain fatty acids (SCFAs) content, and enhanced gut microbial richness and diversity (p < 0.05) in laying hens challenged with C. perfringens and coccidia. Furthermore, the positive effects of BEC on intestinal health were associated with changes in gut microbial composition and structure. In summary, dietary supplementation with BEC has the potential to reduce the severity of intestinal and ovarian damage caused by challenges posed by C. perfringens and coccidia through the modulation of gut microbiota.

Astragalus polysaccharide mitigates Eimeria tenella-induced damage in laying chicks by modulating immunity, inflammation, and intestine barrier

Astragalus polysaccharides (APS), the main active component of the traditional Chinese medicine Astragalus, exhibit immunomodulatory and antioxidant properties. This study analyzed the preventive and therapeutic effects of APS on chicks infected with Eimeria tenellaE. tenella and its impact on intestinal health. A total of 120 1-d-old Hy-Line Brown chicks were assigned to four groups (2 × 2 factorial): 1) Control (0 mg/L APS + 0 sporulated oocysts/chick), 2) APS (1,000 mg/L APS + 0 sporulated oocysts/chick), 3) E. tenellaE. tenella (0 mg/L APS + 5 × 104 sporulated oocysts/chick), 4) E. tenella + APS (1,000 mg/L APS + 5 × 104 sporulated oocysts/chick). The results showed that the addition of APS to the drinking water increased the average daily gain and body weight (day 25) while reduced feed conversion ratio in E. tenella-infected chicks (P < 0.05). APS mitigated cecal lesions (P < 0.05), decreased oocyst shedding (P < 0.05), lowered spleen index (P < 0.05), and elevated bursa and thymus indices (P < 0.05). Serum total protein and alkaline phosphatase activity increased (P < 0.05). Cecal tissue mRNA expression of IL-2, IgG, IgM, Claudin1, Claudin2, ZO-1, and Occludin were increased (P < 0.05), whereas IL-1β, TNF-α, and NF-κB were decreased (P < 0.05). APS enriched cecal f_Lactobacillaceae, g_Lactobacillus, g_Tuzzerella, g_Oscillospira, and g_UBA1819 (P < 0.05). Furthermore, the anticoccidial index (142.10) indicated low-level efficacy. In conclusion, APS alleviated E. tenella damage by modulating immunity, inflammation, microbiota, and intestinal barriers. Although APS demonstrated limited direct anticoccidial activity, its multifaceted protective effects suggest potential in the prevention and treatment of coccidiosis.

The F204S mutation in adrenodoxin oxidoreductase drives salinomycin resistance in Eimeria tenella

Salinomycin is a polyether ionophore widely used for the treatment of coccidiosis in poultry. However, the emergence of coccidia strains resistant to salinomycin presents challenges for control efforts, and the mechanisms underlying this resistance in Eimeria remain inadequately understood. In this study, 78 stable salinomycin-resistant strains were generated through experimental evolution approaches. Whole-genome sequencing of salinomycin-resistant Eimeria tenella isolates revealed single nucleotide polymorphisms (SNPs), with 12 candidate genes harboring nonsynonymous mutations identified. To confirm the candidate gene responsible for conferring salinomycin resistance, we leveraged reverse genetic strategies and identified a key amino acid substitution (F204S) in adrenodoxin oxidoreductase (EtADR), which markedly reduced susceptibility to salinomycin. Our results elucidate the complex interactions among salinomycin resistance, parasite fitness, point mutations, and the structure of EtADR, laying the foundation for future studies on drug resistance in Eimeria and contributing to the development of targeted control strategies.

Surveillance of Drug Residue Profiles in Gallus gallus domesticus (Silkie Chickens) in Taiwan

Veterinary drugs are extensively utilized in poultry farming for purposes such as disease prevention, disease treatment, and feed efficiency enhancement. However, the application of these drugs can lead to unacceptable residues in edible products. This study aimed to investigate the residue profiles of veterinary drugs in silkie chickens. A total of 130 chicken samples were collected from two major retail markets in Taiwan between 2022 and 2024. The analysis of drug residues was conducted using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The overall detection rate of drug residues was 57.7%, and most of these residues were found to be below the maximum residue limits. Among the detected drugs, trimethoprim was the most prevalent, followed by nicarbazin, robenidine, decoquinate, diclazuril, and sulfamonomethoxine. Notably, there was a 31.4% chance that different samples from the same flock would yield varying results. Furthermore, a positive correlation was observed between drug residues and sample weight. In conclusion, this study provides valuable epidemiological data on drug residue profiles in silkie chickens in Taiwan. In the future, it is highly recommended that veterinary drug residues be continuously monitored, and food product sampling protocols be adjusted annually to ensure ongoing compliance with safety standards and protect consumer health.

A Systematic Review and Meta-Analysis of the Efficacy of Biosecurity in Disease Prevention and Control in Livestock Farms in Africa

In Africa, livestock production plays a crucial role for sustainable food security and economic growth. However, the development of this sector has been delayed by livestock diseases, one of the main constraints, which can cause important production and economic losses. To overcome these constraints, farmers extensively use antimicrobials, which in turn can lead to antimicrobial resistance (AMR), one of the main threats to global health and food security. Biosecurity has been identified as a key strategy to reduce livestock diseases. Therefore, the current systematic review and meta-analysis, conducted according to the Cochrane guideline, aimed at determining the efficacy of biosecurity in preventing and controlling infectious diseases in livestock farms in Africa. Of the 1408 records retrieved from five different databases, only 16 met the inclusion criteria. These studies were conducted in Egypt (31.2%), Nigeria (31.2%), Uganda (18.8%), Ethiopia (12.5%) and Tunisia (6.3%) and concerned poultry (62.4%), pigs (18.8%) and cattle (18.8%). Investigations focused mainly on avian influenza (AI) (15.0%) and coccidiosis (10.0%) in poultry and African swine fever (ASF) (10.0%) in pigs. In poultry farms, the results of the pairwise meta-analysis showed that biosecurity measures related to visitors and farmworkers could be effective at reducing the risk of introduction and spread of AI viruses (odds ratio [OR] = 0.48; 95% confidence interval [CI] 0.28-0.82). Moreover, inadequate biosecurity seemed to be a factor promoting coccidiosis (OR = 4.20; 95% CI 2.4-7.4) and AI (OR = 1.74; 95% CI 1.23-2.48). Prevention of ASF was significantly associated with the application of biosecurity measures related to animals' transport, removal of carcasses and manure (OR = 0.33; 95% CI 0.12-0.88). Despite their importance, these findings cannot be translated to the entire African continent, since no studies were available for more than 90% of its countries. More research should be carried out to fill in the gaps identified by this review.

Temporal Changes in Jejunal and Ileal Microbiota of Broiler Chickens with Clinical Coccidiosis (Eimeria maxima)

Coccidiosis in broiler chickens continues to be a major disease of the gastrointestinal tract, causing economic losses to the poultry industry worldwide. The goal of this study was to generate a symptomatic Eimeria maxima (1000 oocysts) infection to determine its effect on the luminal and mucosal microbiota populations (L and M) in the jejunum and ileum (J and IL). Samples were taken from day 0 to 14 post-infection, and sequencing of 16S rRNA was performed using Illumina technology. Infected birds had significantly (p < 0.0001) lower body weight gain (BWG), higher feed conversion ratio (FCR) (p = 0.0015), increased crypt depth, and decreased villus height (p < 0.05). The significant differences in alpha and beta diversity were observed primarily at height of infection (D7). Analysis of taxonomy indicated that J-L and M were dominated by Lactobacillus, and in IL-M, changeover from Candidatus Arthromitus to Lactobacillus as the major taxon was observed, which occurred quicky in infected animals. LEfSe analysis found that in the J-M of infected chickens, Lactobacillus was significantly more abundant in infected (IF) chickens. These findings show that E. maxima infection affects the microbiota of the small intestine in a time-dependent manner, with different effects on the luminal and mucosal populations.

Cassia alata's dual role in modulating MUC2 expression in Eimeria papillata-infected jejunum and assessing its anti-inflammatory effects

Coccidiosis poses significant hazards to animals, particularly in terms of compromised health, reduced productivity, and economic losses in livestock farming. The conventional treatments for coccidiosis often involve synthetic drugs, contributing to concerns about drug resistance and environmental impact. The pressing need for eco-friendly alternatives is highlighted in this study, emphasizing the importance of exploring medicinal plants like Cassia alata leaf extracts (CAE) against Eimeria papillata-induced infection in mice. The CAE exhibited significant phenolic (2.17 ± 0.03 g/100 g) and flavonoid (0.14 ± 0.01 g/100 g) content and demonstrated notable antioxidant activity. In infected mice, the CAE treatment led to a substantial reduction in oocyst output (~6 fold), ameliorating necrotic enteritis and inflammatory changes in the jejunum. Additionally, CAE treatment increased goblet cell numbers (9.3 ± 0.1 / villus) and decreased macrophage infiltration in the intestinal villi. Molecular analyses revealed CAE's positive modulation of MUC2 gene and notably reduced the levels of pro-inflammatory cytokines (specifically IL-1β, IL-10, and IFN-γ) when contrasted with the infected cohort. Furthermore, CAE treatment significantly reduced nitric oxide levels (44.03 ± 2.4 μmol/mg), showcasing its anti-inflammatory properties. The findings of this study not only contribute to the understanding of CAE's therapeutic potential but also underscore the importance of seeking eco-friendly alternatives in the face of coccidiosis challenges, addressing both the well-being of animals and the sustainability of agricultural practices. RESEARCH HIGHLIGHTS: Cassia alata extract (CAE) exhibited significant phenolic and flavonoid content, displaying notable antioxidant activity. In infected mice, CAE treatment led to a substantial reduction in oocyst output, ameliorating necrotic enteritis and inflammatory changes in the jejunum. CAE treatment increased goblet cell numbers and decreased macrophage infiltration in the intestinal villi, while molecular analyses revealed its positive modulation of the MUC2 gene and notable reduction in pro-inflammatory cytokine levels. Additionally, CAE treatment significantly reduced nitric oxide levels, showcasing its anti-inflammatory properties.

Prevalence and determination of species distribution of Eimeria in poultry from the Swabi district, Pakistan

Background and Aim

Coccidiosis, caused by protozoan parasites of the genus Eimeria, is a significant concern in poultry farming, leading to substantial economic losses worldwide. In Pakistan, poultry is a major component of the agricultural sector, with both broiler and egg-laying chickens playing crucial roles in meeting the country's protein needs. Despite the importance of the poultry industry, there is limited data on prevalence and species distribution of Eimeria in different types of chickens in District Swabi, Khyber Pakhtunkhwa, Pakistan. This study aims to estimate the prevalence and determine the distribution of Eimeria species in broiler and egg-laying chickens in this region.

Materials and Methods

Nine hundred fecal samples were collected from broiler (380) and egg-laying domestic chickens (520) in District Swabi, Pakistan. Microscopic analysis was used to identify Eimeria parasites in all samples. After microscopic examination for positive identification, Eimeria species were determined using polymerase chain reaction (PCR) assays.

Results

Microscopic examination identified Eimeria oocysts in 44.4% (400/900) of the samples. Eimeria parasite infection significantly varied based on chicken type, age, and gender (p < 0.05). The study found that broiler chickens (52.63%, 235/450), young chickens (4-6 weeks) (55.5%, 285/500), and females (52.2%, 200/380) were more infected with Eimeria spp. than egg-laying domestic chickens (38.5%, 200/520), adults (above 6 weeks) (28.8%), and males (36.7%, 165/450). PCR indicated a distribution rate of 42.5% (170/400) Eimeria tenella, 26.25% (105/400) Eimeria acervulina, 20% (80/400) Eimeria maxima, and 11.25% (45/400) Eimeria mitis. None of Eimeria necatrix, Eimeria brunetti, or Eimeria praecox was found in the study.

Conclusion

This study underlines the essential requirement for targeted interventions due to the prevalence and predominance of E. tenella among identified Eimeria species. Future research should focus on refined sampling strategies and investigate the clinical significance of these parasites for effective disease management in the local poultry industry.

Electrochemical biosensor for rapid and sensitive monitoring of sulfadimethoxine based on nanoporous carbon and aptamer system

In this study, a straightforward electrochemical aptasensor was developed to detect sulfadimethoxine (SDM). It included a glassy carbon electrode decorated by boron nitride quantum dots (BNQDs) and aptamer-functionalized nanoporous carbon (APT/CZ). CZ was first synthesized by calcinating a zeolitic imidazolate framework (ZIF-8). Then, the electroactive dye methylene blue (MB) was entrapped inside its pores. By attaching aptamer to the CZ surface, APT/CZ acted as a bioguard, which prevented the MB release. Therefore, the electrochemical signal of the entrapped MB was high in the absence of SDM. Introducing SDM caused the conformation of aptamers to change, and a large number of MB was released, which was removed by washing. Therefore, the detection strategy was done based on the change in the electrochemical signal intensity of MB. The aptasensor was applied to detect SDM at a concentration range of 10-17 to 10-7 M with a detection limit of 3.6 × 10-18 M.

Assessing the efficacy of the ovicidal fungus Mucor circinelloides in reducing coccidia parasitism in peacocks

The biological control of gastrointestinal (GI) parasites using predatory fungi has been recently proposed as an accurate and sustainable approach in birds. The current study aimed to assess for the first time the efficacy of using the native ovicidal fungus Mucor circinelloides (FMV-FR1) in reducing coccidia parasitism in peacocks. For this purpose, an in vivo trial was designed in the resident peacock collection (n = 58 birds) of the São Jorge Castle, at Lisbon, Portugal. These animals presented an initial severe infection by coccidia of the genus Eimeria (20106 ± 8034 oocysts per gram of feces, OPG), and thus received commercial feed enriched with a M. circinelloides suspension (1.01 × 108 spores/kg feed), thrice-weekly. Fresh feces were collected every 15 days to calculate the coccidia shedding, using the Mini-FLOTAC technique. The same bird flock served simultaneously as control (t0 days) and test groups (t15-t90 days). The average Eimeria sp. shedding in peacocks decreased up to 92% following fungal administrations, with significant reduction efficacies of 78% (p = 0.004) and 92% (p = 0.012) after 45 and 60 days, respectively. Results from this study suggest that the administration of M. circinelloides spores to birds is an accurate solution to reduce their coccidia parasitism.

Coccidiosis in Egg-Laying Hens and Potential Nutritional Strategies to Modulate Performance, Gut Health, and Immune Response

Avian coccidiosis, despite advancements in management, nutrition, genetics, and immunology, still remains the most impactful disease, imposing substantial economic losses to the poultry industry. Coccidiosis may strike any avian species, and it may be mild to severe, depending on the pathogenicity of Eimeria spp. and the number of oocysts ingested by the bird. Unlike broilers, low emphasis has been given to laying hens. Coccidiosis in laying hens damages the gastrointestinal tract and causes physiological changes, including oxidative stress, immunosuppression, and inflammatory changes, leading to reduced feed intake and a drastic drop in egg production. Several countries around the world have large numbers of hens raised in cage-free/free-range facilities, and coccidiosis has already become one of the many problems that producers have to face in the future. However, limited research has been conducted on egg-laying hens, and our understanding of the physiological changes following coccidiosis in hens relies heavily on studies conducted on broilers. The aim of this review is to summarize the effect of coccidiosis in laying hens to an extent and correlate it with the physiological changes that occur in broilers following coccidiosis. Additionally, this review tries to explore the nutritional strategies successfully used in broilers to mitigate the negative effects of coccidiosis in improving the gut health and performance of broilers and if they can be used in laying hens.

First insights on the susceptibility of native coccidicidal fungi Mucor circinelloides and Mucor lusitanicus to different avian antiparasitic drugs

BACKGROUND

The combined application of predatory fungi and antiparasitic drugs is a sustainable approach for the integrated control of animal gastrointestinal (GI) parasites. However, literature addressing the possible interference of antiparasitic drugs on the performance of these fungi is still scarce. This research aimed to assess the in vitro susceptibility of six native coccidicidal fungi isolates of the species Mucor circinelloides and one Mucor lusitanicus isolate to several antiparasitic drugs commonly used to treat GI parasites' infections in birds, namely anthelminthics such as Albendazole, Fenbendazole, Levamisole and Ivermectin, and anticoccidials such as Lasalocid, Amprolium and Toltrazuril (drug concentrations of 0.0078-4 µg/mL), using 96-well microplates filled with RPMI 1640 medium, and also on Sabouraud Agar (SA).

RESULTS

This research revealed that the exposition of all Mucor isolates to the tested anthelminthic and anticoccidial drug concentrations did not inhibit their growth. Fungal growth was recorded in RPMI medium, after 48 h of drug exposure, as well as on SA medium after exposure to the maximum drug concentration.

CONCLUSIONS

Preliminary findings from this research suggest the potential compatibility of these Mucor isolates with antiparasitic drugs for the integrated control of avian intestinal parasites. However, further in vitro and in vivo studies are needed to confirm this hypothesis.

Polyether ionophore resistance in a one health perspective

Antimicrobial resistance is a major threat to human health and must be approached from a One Health perspective. Use of antimicrobials in animal husbandry can lead to dissemination and persistence of resistance in human pathogens. Polyether ionophores (PIs) have antimicrobial activities and are among the most extensively used feed additives for major production animals. Recent discoveries of genetically encoded PI resistance mechanisms and co-localization of resistance mechanisms against PIs and antimicrobials used in human medicine on transferrable plasmids, have raised concerns that use of PIs as feed additives bear potential risks for human health. This review summarizes the current knowledge on PI resistance and discusses the potential consequences of PI-usage as feed additives in a One Health perspective.

LC-MS/MS analysis of coccidiostats in meat supply chain safety

The presence of coccidiostats in meat products represents an important topic because of the animal administration of these substances, authorized as feed additives for targeted species, in order to prevent and inhibit coccidiosis. Coccidiostats include both ionophores and synthetic molecules characterized by different chemical-physical properties such as polarity. Meat is a matrix characterized by many interfering compound groups, such as proteins, phospholipids, and fats. High-performance liquid chromatography (HPLC) coupled to mass spectrometry (MS) analysis allows the required selectivity and sensitivity for discriminating analytes and matrix interferences. For these reasons, an LC-MS/MS method for the analysis of coccidiostats in meat products was developed without SPE purification steps. The correct analyte quantification is allowed by matrix-matched calibration. The method validation was performed by the replicated analysis of spiked meat samples at two different concentration levels (limit of quantification-LOQ-and a 10 times LOQ) in order to evaluate method recovery and repeatability, plus spiked samples at higher concentrations up to 10,000 μg/kg. Moreover, the metrological approach was used for the calculation of method uncertainty. The application of the developed method to real samples evidenced the presence of some non-ionophores coccidiostats in the meat and liver of chicken and rabbit species. Although, the determined concentration was below the established MRLs, the monitoring of coccidiostats in the meat supply chain is confirmed as a good strategy in order to safeguard consumer health.

Management and control of coccidiosis in poultry - A review

Poultry coccidiosis is an intestinal infection caused by an intracellular parasitic protozoan of the genus Eimeria. Coccidia-induced gastrointestinal inflammation results in large economic losses, hence finding methods to decrease its prevalence is critical for industry participants and academic researchers. It has been demonstrated that coccidiosis can be effectively controlled and managed by employing anticoccidial chemical compounds. However, as a result of their extensive use, anticoccidial drug resistance in Eimeria species has raised concerns. Phytochemical/herbal medicines (Artemisia annua, Bidens pilosa, and garlic) seem to be a promising strategy for preventing coccidiosis, in accordance with the "anticoccidial chemical-free" standards. The impact of herbal supplements on poultry coccidiosis is based on the reduction of oocyst output by preventing the proliferation and growth of Eimeria species in chicken gastrointestinal tissues and lowering intestinal permeability via increased epithelial turnover. This review provides a thorough up-to-date assessment of the state of the art and technologies in the prevention and treatment of coccidiosis in chickens, including the most used phytochemical medications, their mode of action, and the applicable legal framework in the European Union.

Quantitative Analysis of Decoquinate Residues in Hen Eggs through Derivatization-Gas Chromatography Tandem Mass Spectrometry

A novel precolumn derivatization-gas chromatography tandem mass spectrometry (GC-MS/MS) method was developed to detect and confirm the presence of decoquinate residues in eggs (whole egg, albumen and yolk). Liquid-liquid extraction (LLE) and solid phase extraction (SPE) were used to extract and purify samples. The derivatization reagents were pyridine and acetic anhydride, and the derivatives were subjected to GC-MS/MS detection. After the experimental conditions were optimized, satisfactory sensitivity was obtained. The limits of detection (LODs) and limits of quantification (LOQs) for the decoquinate in eggs (whole egg, albumen and yolk) were 1.4-2.4 μg/kg and 2.1-4.9 μg/kg, respectively. At four spiked concentration levels, the average recoveries were 74.3-89.8%, the intraday RSDs ranged from 1.22% to 4.78%, and the inter-day RSDs ranged from 1.61% to 7.54%. The feasibility and practicality of the method were confirmed by testing egg samples from a local supermarket.

Effect of an Alliaceae Encapsulated Extract on Growth Performance, Gut Health, and Intestinal Microbiota in Broiler Chickens Challenged with Eimeria spp

This study analyzed the effects of an Alliaceae encapsulated extract (AE-e) on daily gain (ADG), feed intake (ADFI), feed conversion ratio (FCR), oocysts per gram of feces (OPG), intestinal lesion (LS), and microbiota composition in broilers challenged with Eimeria spp. A total of 4800 one day Cobb-500 were allotted into 10 treatment groups with 12 replicates of 40 birds in a 2 × 4 + 2 factorial arrangement. The first factor was non-challenged (NC) or challenged (C), the second was four levels of AE-e added in the basal diet, 0 (AE0), 250 (AE250), 500 (AE500), and 750 mg·kg-1 (AE750), plus two ionophore controls, non-challenged (NC-Ion) and challenged (C-Ion). No interactions were observed between factors (NC0, NC250, NC500, NC750, C0, C250, C500, and C750), while C-Ion improved FCR at 21 d. The challenge affected negatively ADG and FCR and promoted enteropathogens in cecum. AE750 improved FCR in the finisher and cumulative phases, while C-Ion had fewer total OPG than C0 and C250. Likewise, at 21d, C250, C500, and C-Ion had fewer LS than C0, while at 28 d, C750 showed lower than C-Ion. In the cecum microbiota, C500 had more Ruminococcus, Firmicutes b, and Intestinimonas than C-Ion. In summary, AE-e showed beneficial results in broilers infected with Eimeria spp.

A rhoptry protein, localizing in the bulb region of rhoptries, could induce protective immunity against Eimeria tenella infection

Background

Rhoptry organelle proteins (ROPs) secreted by apicomplexan parasites play important roles during parasites invasion and survival in host cells, and are potential vaccine candidates against apicomplexan diseases. Eimeria tenella (E. tenella) is one of the most noteworthy apicomplexan species, which causes hemorrhagic pathologies. Although dozens of putative E. tenella ROP sequences are annotated, most ROP proteins are not well studied.

Methods

In this study, an E. tenella ROP21 gene was identified and the recombinant EtROP21 protein (rEtROP21) was expressed in Escherichia coli. The developmental expression levels, localization, and protective efficacy against E. tenella infection in chickens were studied.

Results

An EtROP21 gene fragment with an open reading frame (ORF) of 981 bp was obtained from the Beijing strain of E. tenella. The rEtROP21 has a molecular weight of approximately 50 kDa and was recognized by rEtROP21-immunized mouse serum. Two specific protein bands, about 43 KDa and 95 KDa in size, were detected in the whole sporozoite proteins using the rEtROP21-immunized chicken serum. RT-qPCR analysis of the E. tenella ROP21 gene (EtROP21) revealed that its mRNA levels were higher in merozoites and sporozoites than in sporulated and unsporulated oocysts. Immunofluorescence and immunoelectron analyses showed that the EtROP21 protein predominantly localizes in the bulb region of rhoptries distributed at anterior, posterior, and perinuclear regions of E. tenella sporozoites. Immunization and challenge experiments revealed that immunizing chickens with rEtROP21 significantly increased their average body weight gain while decreasing mean lesion score and oocyst output (P <0.05). When compared with the challenged control group, the rEtROP21-immunized group was associated with a significantly higher relative weight gain (90.2%) and a greater reduction in oocyst output (67%) (P <0.05). The anticoccidial index of the rEtROP21-immunized group was 163.2. Chicken serum ELISA revealed that the levels of the specific anti- rEtROP21 antibody, IFN-γ, and IL-4 were significantly higher in the rEtROP21-immunized group than in the challenged control group (P <0.05).

Conclusion

These results indicate that rEtROP21 can induce a high level of specific immune response and it is a potential candidate for the development of vaccines against E. tenella infection in chickens.

Live attenuated anticoccidial vaccines for chickens

Chicken coccidiosis, caused by infection with single or multiple Eimeria species, results in significant economic losses to the global poultry industry. Over the past decades, considerable efforts have been made to generate attenuated Eimeria strains, and the use of live attenuated anticoccidial vaccines for disease prevention has achieved tremendous success. In this review, we evaluate the advantages and limitations of the methods of attenuation as well as attenuated Eimeria strains in a historical perspective. Also, we summarize the recent exciting research advances in transient/stable transfection systems and clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editing developed for Eimeria parasites, and discuss trends and challenges of developing live attenuated anticoccidial vaccines based on transgenesis and genome editing.

Assessing the effects of a mixed Eimeria spp. challenge on performance, intestinal integrity, and the gut microbiome of broiler chickens

A mixed Eimeria spp. challenge model was designed to assess the effects of challenge on broiler chicken performance, intestinal integrity, and the gut microbiome for future use to evaluate alternative strategies for controlling coccidiosis in broiler chickens. The experimental design involved broiler chickens divided into two groups: a control group (uninfected) and a positive control group, infected with Eimeria acervulina (EA), Eimeria maxima (EM), and Eimeria tenella (ET). At day-of-hatch, 240 off-sex male broiler chicks were randomized and allocated to one of two treatment groups. The treatment groups included: (1) Non-challenged (NC, n = 5 replicate pens); and (2) challenged control (PC, n = 7 replicate pens) with 20 chickens/pen. Pen weights were recorded at d0, d16, d31, d42, and d52 to determine average body weight (BW) and (BWG). Feed intake was measured at d16, d31, d42, and d52 to calculate feed conversion ratio (FCR). Four diet phases included a starter d0-16, grower d16-31, finisher d31-42, and withdrawal d42-52 diet. At d18, chickens were orally challenged with 200 EA, 3,000 EM, and 500 ET sporulated oocysts/chicken. At d24 (6-day post-challenge) and d37 (19-day post-challenge), intestinal lesion scores were recorded. Additionally, at d24, FITC-d was used as a biomarker to evaluate intestinal permeability and ileal tissue sections were collected for histopathology and gene expression of tight junction proteins. Ileal and cecal contents were also collected to assess the impact of challenge on the microbiome. BWG and FCR from d16-31 was significantly (p < 0.05) reduced in PC compared to NC. At d24, intestinal lesion scores were markedly higher in the PC compared to the NC. Intestinal permeability was significantly increased in the PC group based on serum FITC-d levels. Cadherin 1 (CDH1), calprotectin (CALPR), and connexin 45 (Cx45) expression was also upregulated in the ileum of the PC group at d24 (6-day post-challenge) while villin 1 (VIL1) was downregulated in the ileum of the PC group. Additionally, Clostridium perfringens (ASV1) was enriched in the cecal content of the PC group. This model could be used to assess the effect of alternative coccidiosis control methods during the post-challenge with EA, EM, and ET.

Molecular characterization and protective efficacy of vacuolar protein sorting 29 from Eimeria tenella

Introduction

Vacuolar protein sorting 29 (VPS29) is a core component of the retromer-retriever complex and is essential for recycling numerous cell-surface cargoes from endosomes. However, there are no reports yet on VPS29 of Eimeria spp.

Methods

Here, we cloned and prokaryotically expressed a partial sequence of Eimeria tenella VPS29 (EtVPS29) with RT-PCR and engineered strain of Escherichia coli respectively. The localization of the VPS29 protein in E. tenella sporozoites was investigated with immunofluorescence (IFA) and overexpression assays. And its protective efficacy against E. tenella infection was investigated in chickens with the animal protection test.

Results

An EtVPS29 gene fragment with an ORF reading frame of 549 bp was cloned. The band size of the expressed recombinant protein, rEtVPS29, was approximately 39 kDa and was recognized by the chicken anti-E. tenella positive serum. EtVPS29 protein was observed widely distributing in the cytoplasm of E. tenella sporozoites in the IFA and overexpression assays. rEtVPS29 significantly increased average body weight gain and decreased mean lesion score and oocyst output in chickens. The relative weight gain rate in the rEtVPS29-immunized group was 62.9%, which was significantly higher than that in the unimmunized and challenged group (P < 0.05). The percentage of reduced oocyst output in the rEtVPS29 immunized group was 32.2%. The anticoccidial index of the rEtVPS29-immunized group was 144.2. Serum ELISA also showed that rEtVPS29 immunization induced high levels of specific antibodies in chickens.

Discussion

These results suggest that rEtVPS29 can induce a specific immune response and is a potential candidate for the development of novel vaccines against E. tenella infections in chickens.

Botanicals: A promising approach for controlling cecal coccidiosis in poultry

Avian species have long struggled with the problem of coccidiosis, a disease that affects various parts of the intestine, including the anterior gut, midgut, and hindgut. Among different types of coccidiosis, cecal coccidiosis is particularly dangerous to avian species. Chickens and turkeys are commercial flocks; thus, their parasites have remained critical due to their economic importance. High rates of mortality and morbidity are observed in both chickens and turkeys due to cecal coccidiosis. Coccidiostats and coccidiocidal chemicals have traditionally been added to feed and water to control coccidiosis. However, after the EU banned their use because of issues of resistance and public health, alternative methods are being explored. Vaccines are also being used, but their efficacy and cost-effectiveness remain as challenges. Researchers are attempting to find alternatives, and among the alternatives, botanicals are a promising choice. Botanicals contain multiple active compounds such as phenolics, saponins, terpenes, sulfur compounds, etc., which can kill sporozoites and oocysts and stop the replication of Eimeria. These botanicals are primarily used as anticoccidials due to their antioxidant and immunomodulatory activities. Because of the medicinal properties of botanicals, some commercial products have also been developed. However, further research is needed to confirm their pharmacological effects, mechanisms of action, and methods of concentrated preparation. In this review, an attempt has been made to summarize the plants that have the potential to act as anticoccidials and to explain the mode of action of different compounds found within them.

In Vitro: The Effects of the Anticoccidial Activities of Calotropis procera Leaf Extracts on Eimeria stiedae Oocysts Isolated from Rabbits

Hepatic coccidiosis is an infectious and mortal disease that causes global economic losses in rabbits. The research aimed to assess the efficacy of Calotropis procure leaf extracts on the inhibition of Eimeria stiedae oocysts and to determine the optimal dosage for suppressing the parasite's infective phase. In this experiment, oocyst samples per milliliter were tested, and 6-well plates (2 mL) of 2.5% potassium dichromate solution containing 10² non-sporulated oocysts on Calotropis procera leaf extracts were exposed after 24, 48, 72, and 96 h, and the treatments were as follows: a nontreated control, 25%, 50%, 100%, and 150% of C. procera for oocyst activities. In addition, amprolium was utilized as a reference drug. The Calotropis procera was analyzed by GC-Mass, and results showed that the botanical extract contained 9 chemical components that were able to inhibit the oocysts of E. stiedae at 100% and 150% concentrations by about 78% and 93%, respectively. In general, an increase in the incubation period and a greater dose resulted in a decrease in the inhibition rate. The results showed that C. procera has an effective ability, inhibitory potential, and protective effect on the coccidian oocyst sporulation of E. stiedae. It can be used in the disinfection and sterilization of poultry and rabbit houses to get rid of Eimeria oocysts.

Development and Validation of a Confirmatory Method for the Determination of 12 Coccidiostat Residues in Eggs and Muscle by Means of Liquid Chromatography Coupled to Hybrid High Resolution Mass Spectrometry

A confirmatory, highly selective multi-residue method based on liquid chromatography coupled to hybrid high resolution mass spectrometry (LC-Q-Orbitrap) was developed and validated for the determination of 12 regulated coccidiostats in eggs and muscle. Particularly, ionophore antibiotics (lasalocid, maduramicin, monensin, narasin, salinomycin and semduramicin) and synthetic coccidiostats (diclazuril, halofuginone, nicarbazin as 4,4′-dinitrocarbanilide fraction, robenidine and toltrazuril as toltrazuril-sulphone) were included in the method. The sample preparation consisted in the extraction of the analytes from the matrix with acetonitrile, followed by a clean-up step with Oasis® PRiME HLB SPE and a defatting procedure with n-hexane. Validation was successfully performed according to Commission Implementing Regulation (EU) 2021/808, starting from 1 µg kg−1. The procedure was verified through the analysis of a certified reference material (CRM) and the occurrence of the residues was assessed in the context of the Italian National Residue Control Plan (NRCP).

Risk Assessment of Nine Coccidiostats in Commercial and Home-Raised Eggs

The poultry industry, in order to prevent and control coccidiosis caused by Eimeria spp., widely uses coccidiostats as feed additives. The main objective of this study was to evaluate the presence of nine coccidiostats in 62 egg samples by UHPLC-MS/MS. Overall, detection frequency and average concentration were 90.3% (56/62) and 106.3 μg kg−1, respectively. Only diclazuril and nicarbazin were detected. Diclazuril, only found in home-raised eggs, showed an overall detection frequency of 8.1% (5/62), with average and maximum concentrations of 0.46 ± 1.90 μg kg−1 and 13.6 μg kg−1, respectively. Nicarbazin presented an overall higher frequency, 88.7% (55/62), with levels up to 744.8 μg kg−1. Additionally, four samples (6.5%) presented both nicarbazin and diclazuril. Home-raised egg samples (n = 28) showed a detection frequency of 89.3%, with nicarbazin found in more samples (85.7% vs. 17.9%) and at higher levels (266.3 ± 169.4 μg kg−1 vs. 0.91 ± 2.78 μg kg−1) when compared to diclazuril. In supermarket samples (n = 34), only nicarbazin was detected in 31 samples (91.1%), with an average of 167.6 ± 62.2 μg kg−1. Considering the average contamination scenario, consumers’ health should not be adversely affected by egg consumption. In every scenario considered, children were the most vulnerable population group.

A century of "anticoccidial drugs": bibliometric analysis

Publications are an important measure of scientific and technological progress. The quantitative examination of the number of publications in a certain research topic is known as bibliometrics. Bibliographic studies are widely used to analyse the condition of research, future potential, and current growth patterns in a certain topic. It can serve as a basis for making decisions and implementing strategies to achieve long-term development goals. To our knowledge, no research has been conducted in these domains; so, this work aims to employ bibliometric analysis to provide comprehensive data on publications related to anticoccidial drugs. As a result, the current study uses bibliometric analysis to track the evolution of anticoccidial drugs and its consequences in the academic and public worlds via a survey of relevant scientific and popular publications. The Dimensions database was used to retrieve the bibliographical statistics, which were then cleaned and analyzed. The data was also loaded into the VOS viewer, which generated a network visualization of the authors with the most joint articles. The investigation discovered three stages of publications and citations since the first article on anticoccidial drugs in 1949. The first stage, which ran from 1920 to 1968, was characterized by a scarcity of research articles on anticoccidial drugs. From 1969 to 2000, the second stage was marked by a stable and marginally increased number of articles. The scientific field was characterized by an increasing trend in the number of publications and their citations from 2002 to 2021. The study gave a complete list of the top anticoccidial drugs funding agents, countries, research institutes, most cited publications, and important co-authorship and partnerships. The outcomes of the study will help veterinary practitioners and researchers understand the trends and best sources of knowledge in the field of anticoccidial medications.

Potency of Origanum vulgare and Andrographis paniculata extracts on growth performance in poultry

The objective of this study was to investigate the effect of phytobiotics combination of Origanum vulgare and Andrographis paniculata water extracts (FOA) mixed into the feed of broiler and specific-pathogen-free chickens as an alternative to Antibiotics Growth Promoter (AGP). Performance, intestinal bacteria characteristic, and oocysts of Eimeria spp. in feces were measured and compared with the AGP-added group. The first experiment in broiler chickens compared FOA, Zinc Bacitracin (ZB, as an AGP group), and negative control. On day 28, FOA group and ZB group showed significantly higher body weight than the control group (P < 0.05). The FCR of ZB group was better than FOA group. However, FOA group displayed better microbiota profile than ZB group and negative control, with more Lactobacillus spp. and Bacillus spp., and less Escherichia coli and Salmonella spp. isolated from intestines. The second experiment in specific-pathogen-free chickens showed the anticoccidial effect of FOA addition to reduce the number of oocysts per gram (OPG) from live coccidia vaccine. FOA group and Amprolium group showed OPG reduction (82.53% and 92.02%, respectively) after 7 days of treatment. In conclusion, the combination of Origanum vulgare and Andrographis paniculata extract can function as an AGP replacement in feed.

Nicarbazin Residue in Tissues from Broilers Reared on Reused Litter Conditions

Nicarbazin (NCZ) is a worldwide used anticoccidial in poultry farming to avoid coccidiosis disease when chickens are reared on conventional poultry litter. If proper dosage and withdrawal time are not followed, the component dinitrocarbanilide (DNC) of NCZ may be present in chicken tissues, therefore posing a risk to consumers if the residues are above 200 µg/kg. Litter reuse is a common and important practice in commercial chicken production. Literature is lacking about the influence of litter reuse on DNC deposition in chicken tissues and its impact on food safety. We aimed to evaluate DNC residues in breast and liver by LC-MS/MS from broilers from an experiment with 10 consecutive flocks during 2 years. The experiment included three treatments containing NCZ in the diet (T1 = 125 mg/kg, 1−21 d; T2 = 125 mg/kg, 1−32 d; T3 = 40 mg/kg, 1−32 d). DNC residues in chicken breast at 21 d in T1 ranged from 648.8−926 µg/kg, at 32 d in T2 and T3 varied, respectively, from 232−667 µg/kg and 52−189 µg/kg. Regarding liver, DNC residues at 21 days in T1 ranged from 11,754−15,281 µg/kg, at 32 days in T2 and T3 varied, respectively, from 10,168−15,021 µg/kg and 2899−4573 µg/kg. When NCZ was withdrawn from feed, DNC residues dropped to <LOQ at 42 d in all treatments. Therefore, the reuse of poultry litter does not compromise food safety regarding DNC residues in chicken tissues, as shown herein up to 10 flocks.