Coccidiosis: recent advancements in the immunobiology of Eimeria species, preventive measures, and the importance of vaccination as a control tool against these Apicomplexan parasites

Alternatives to antibiotics against coccidiosis for poultry production: the relationship between immunity and coccidiosis management – a comprehensive review

Avian coccidiosis is a protozoan infection caused by numerous Eimeria parasitic species and mainly affects the bird’s gastrointestinal tract and results in a reduction of the bird ‘ability to absorb nutrients, slower growth, with a higher mortality rate. According to recent research, immune-based treatments, such as dietary immunomodulating feed additives and recombinant vaccines, can help the hosts protect themselves from intracellular parasites and reduce inflammatory reactions caused by parasites. Coccidiosis control in the post-antiparasitic stage requires thoroughly investigation of the intricate relationships between the parasites, host defense system, enteroendocrine system, and gut microbiome contributing to coccidian infections. To produce a vaccine, it is crucial to explore the defense mechanism of the intestine’s immune machinery and to identify many effector molecules that act against intracellular parasites. Due to the massive usage of chemical anticoccidial drugs, coccidiosis developed resistant against most commonly used anticoccidials; therefore, numerous researches focused on the usage of safe natural anticoccidials such as probiotics, prebiotics, organic acids, and essential oils to counteract such resistance problem. This review describes how host immunity responds to coccidial infection in chickens and the use of some nonantiparasitic safe natural alternative controls to counter the disease. It would throw the light on the possibility of developing effective therapies against Eimeria to alleviate the detrimental effects of avian coccidiosis.

Efficacy of myrrh extract against Eimeria labbeana-like experimental infection in Columba livia domestica: in vivo study

BACKGROUND

The Protozoan pathogen Eimeria is a significant issue in poultry production. Scientists are concerned with finding alternative strategies due to the spread of resistance against the commonly employed coccidiostats. This study examined how well myrrh extract (MyE) protected domesticated pigeons from an experimental Eimeria labbeana-like infection.

METHODS

Female pigeons were divided into six groups (5 pigeons/group): Group1: control pigeon group, Group2: Non-infected and treated pigeon group with MyE (500 mg/kg). Group3: Infected and non-treated pigeon group, Group4: Infected and treated pigeon group with MyE (250 mg/kg), Group5: Infected and treated pigeon group with MyE (500 mg/kg), Group6: Infected and treated pigeon group with amprolium (1 g/L of H2O). Oral infection with 3 × 104 sporulated E. labbeana-like oocysts was used to inoculate groups (3-6). Three days after infection, groups (4-6) received daily treatment with MyE and amprolium for five days. Oocyst output was assessed on day 8 post-infection. After sacrificing the pigeons, the small intestine and blood were collected from each pigeon and processed for histological, biochemical, and oxidative damage examinations.

RESULTS

This study looked into the overall phenolic and flavonoid contents and MyE's antioxidant activity. According to the data, the best dose of MyE was 500 mg/kg, which significantly decreased the output of oocysts produced (2.090 × 105 ± 1.04 × 104 oocysts/g.feces). This result has been linked to a -2.51% decrease in the pigeon's body weight gain. The morphometric characteristics of freshly unsporulated and sporulated oocysts were obtained, and pigeons treated with MyE significantly decreased size. Furthermore, there was a significant decrease in both the number and size of the developmental stages of E. labbeana-like (i.e. meronts, gamonts, and developing oocysts) in the intestinal tissue among the MyE-treated group. MyE facilitates the disruption of intestinal homeostasis caused by E. labbeana-like infection, specifically concerning carbohydrates and proteins. Concurrent with the state of total antioxidant capacity (TAC), the antioxidant activity of MyE reduced the blood plasma levels of trace elements (Fe, Cu, Cr, Zn, and Ni).

CONCLUSION

Our findings suggest that MyE could be a useful antioxidant source and a replacement for coccidiostats in preventing and treating avian coccidiosis.

Investigation of the heat shock protein 70 activity in intestine cells of goats with coccidiosis

Coccidiosis is one of the most common infectious diseases in goat farming. The disease causes major economic loss in the world. In this study, we aimed to investigate the activity of heat shock protein 70 in intestine cells of goats with coccidiosis. We used total of twenty-seven goats for this purpose. Gross findings were diarrhoea, cachexia, and dehydration. In the microscopical examination, we observed proliferative enteritis with Eimeria. parasites. Immunohistochemical examinations revealed moderate to severe Hsp70 immunoreactivity in intestines. Considering Hsp70 is a stress protein with anti-apoptotic and immune regulatory features, Hsp70 immunoreactivity attributed to the stress caused by infection and anti-apoptotic activity of the protein along with immune regulatory effects of Hsp70.

Use of Metallic Nanoparticles Against Eimeria-the Coccidiosis-Causing Agents: A Comprehensive Review

Coccidiosis is a protozoan disease caused by Eimeria species and is a major threat to the poultry industry. Different anti-coccidial drugs (diclazuril, amprolium, halofuginone, ionophores, sulphaquinoxaline, clopidol, and ethopabate) and vaccines have been used for their control. Still, due to the development of resistance, their efficacy has been limited. It is continuously damaging the economy of the poultry industry because under its control, almost $14 billion is spent, globally. Recent research has been introducing better and more effective control of coccidiosis by using metallic and metallic oxide nanoparticles. Zinc, zinc oxide, copper, copper oxide, silver, iron, and iron oxide are commonly used because of their drug delivery mechanism. These nanoparticles combined with other drugs enhance the effect of these drugs and give their better results. Moreover, by using nanotechnology, the resistance issue is also solved because by using several mechanisms at a time, protozoa cannot evolve and thus resistance cannot develop. Green nanotechnology has been giving better results due to its less toxic effects. Utilization of metallic and metallic oxide nanoparticles may present a new, profitable, and economical method of controlling chicken coccidiosis, thus by changing established treatment approaches and improving the health and production of chickens. Thus, the objective of this review is to discuss about economic burden of avian coccidiosis, zinc, zinc oxide, iron, iron oxide, copper, copper oxide, silver nanoparticles use in the treatment of coccidiosis, their benefits, and toxicity.

The financial cost of coccidiosis in Algerian chicken production: a major challenge for the poultry sector

Coccidiosis, caused by parasites of the genus Eimeria, is a significant economic burden to the poultry industry. In this study, we conducted a comprehensive analysis to evaluate the financial losses associated with Eimeria infection in chickens in Algeria, relying on data provided by key stakeholders in the Algerian poultry industry to assess sub-clinical as well as clinical impact. We employed the updated 2020 version of a model established to estimate the cost of coccidiosis in chickens, taking into consideration specific cultural and technical aspects of poultry farming in Algeria. The findings predict economic losses due to coccidiosis in chickens of approximately £86.7 million in Algeria for the year 2022, representing £0.30 per chicken raised. The majority of the cost was attributed to morbidity (74.9%), emphasizing the substantial economic impact of reduced productivity including decreased bodyweight gain and increased feed conversion ratio. Costs associated with control measures made up 20.5% of the total calculated cost, with 4.6% of the cost related to mortality. These figures provide a clear indication of the scope and economic impact of Eimeria infection of chickens in Algeria, illustrating the impact of practices common across North Africa. They underscore the ongoing requirement for effective preventive and control measures to reduce these financial losses while improving productivity and welfare, ensuring the economic sustainability of the Algerian poultry industry.

Mycotoxins and coccidiosis in poultry - co-occurrence, interaction, and effects

Avian coccidiosis, a common disease caused by Eimeria species, results in significant losses in global poultry production. Mycotoxins are low-molecular-weight natural products (i.e., small molecules) produced as secondary metabolites by filamentous fungi and they have the potential to economically and significantly affect global poultry production. Little is known about the relationship between mycotoxins and avian coccidiosis, although they often co-occur in the field. This comprehensive review examines the intricate relationship between mycotoxins and avian coccidiosis, in particular how mycotoxins, including aflatoxins, ochratoxins, trichothecenes as well as Fusarium mycotoxins, compromise the health of the poultry flock and open the door to Eimeria parasites in the gut. In addition, this review sheds light on the immunosuppressive effects of mycotoxins, their disruption of cellular signaling pathways, and the consequent exacerbation of coccidiosis infections. The mechanisms of mycotoxin toxicity are also reviewed, emphasizing direct damage to intestinal epithelial cells, impaired nutrient absorption, inflammation, oxidative stress, and changes in the gut microbiota. Finally, the consequences for the prevention and treatment of coccidiosis when mycotoxins are present in the feed are discussed. This review emphasizes the need for effective management strategies to mitigate the combined risks of mycotoxins and coccidiosis and highlights the complexity of diagnosing and controlling these interrelated problems in poultry. The review advocates a holistic approach that includes strict feed management, disease prevention measures and regular monitoring to maintain the health and productivity of poultry against these significant challenges.

Development of a TaqMan polymerase chain reaction detection method for the precise identification and quantification of an attenuated Eimeria maxima vaccine strain in poultry

Avian coccidiosis, a parasitic disease prevalent in poultry, is caused by Eimeria species and leads to significant economic losses. The use of attenuated live oocyst vaccines has been adopted as an alternative to the use of anticoccidial drugs. However, the accurate detection and differentiation of vaccine strains from virulent ones remain challenging. Therefore, this study presents a novel TaqMan polymerase chain reaction (PCR) detection method that offers enhanced sensitivity, specificity, and reproducibility compared with traditional PCR techniques. Through whole-genome resequencing and bioinformatics analysis, we identified a molecular marker gene, Em_marker6, with a unique 21-base pair deletion specific to the Eimeria maxima attenuated vaccine strain. Optimized primers and probes targeting this marker enabled rapid quantification cycle value achievement and high fluorescence intensity. The standard curve's slope of -3.540 and correlation coefficient of 0.9971 confirmed precise quantification capabilities. The TaqMan PCR method detected as few as 30 plasmid DNA copies and 50 oocysts per reaction, outperforming traditional PCR techniques by an order of magnitude. No cross-reactivity was observed with other E. maxima wide-type strains or common intestinal pathogens, ensuring the exclusive detection of the E. maxima EMPY vaccine strain. Weekly testing over 3 weeks demonstrated minimal variability, indicating robust consistency in the method's application. Testing on 61 clinical samples revealed a 57.38% positivity rate for E. maxima species and 13.11% for the vaccine strain. The Em_marker6 gene exhibited genetic stability across multiple generations, confirming the detection method's robust stability for the attenuated E. maxima vaccine strain. This study significantly advances the field of avian coccidiosis research and control by providing a valuable tool for monitoring vaccine purity and preventing inadvertent infections in vaccinated flocks, aligning with global efforts to curb antibiotic use in animal feed.

Eukaryotic Infections in Dairy Calves: Impacts, Diagnosis, and Strategies for Prevention and Control

Eukaryotic infections are common among dairy calves and can have significant impacts on their health and growth rates. Fungal infections caused by Aspergillus fumigatus, Trichophyton verrucosum, and Candida albicans can cause respiratory diseases, dermatophytosis, and diarrhea, respectively. Protozoan parasites, including Cryptosporidium parvum, Giardia duodenalis, and Eimeria spp., are also common in dairy calves. C. parvum is highly contagious and can cause severe diarrhea and dehydration, while Giardia duodenalis can lead to poor growth and is transmissible to humans through contaminated food or water. Eimeria spp. can cause coccidiosis and lead to reduced growth rates, poor feed conversion, and death. The common helminthic infections in dairy calves include Ostertagia ostertagi, Cooperia spp., Fasciola hepatica, and Strongyloides papillosus. These parasitic infections significantly impact calf health, growth, and dairy industry productivity. Diagnosis of these infections can be made through fecal samples using microscopy or molecular methods. However, diagnosis of the infections can be challenging and requires a combination of clinical signs and laboratory tests such as culture and PCR. Preventing and controlling eukaryotic infections in dairy calves requires several measures. Good hygiene and sanitation practices, proper management strategies, and timely treatment of affected animals are important. It is also necessary to avoid overcrowding and consider vaccination against ringworm. Further research is needed to better understand the epidemiology and characterization of eukaryotic infections in dairy calves, which will help in the development of more effective prevention and control strategies. In general, good hygiene practices, appropriate management strategies, and timely treatment of affected animals are crucial in preventing and controlling the infections, ensuring the health and well-being of dairy calves.

Attenuation of pathogenesis of Eimeria stiedae sporulated oocysts using Egyptian alginate propolis nanoparticles

BACKGROUND

Coccidiosis is a costly and widespread infectious disease that affects mammals and causes huge losses for the global rabbit meat industry. This study evaluated the potency of Egyptian alginate propolis nanoparticles (NPs) in attenuating the infectivity of Eimeria stiedae sporulated oocysts. The gelification method was used to prepare alginate propolis NPs, which were then characterized using a transmission electron microscope and zeta potential analysis.

RESULTS

The results revealed that the zeta potential of the prepared alginate propolis NPs increased from - 60.60 ± 9.10 mV to -72.26 ± 6.04 mV. The sporulated oocysts were treated with 50 mg/mL of the alginate propolis NPs. Thereafter, the treated oocysts were tested for their ability to infect rabbits. The rabbits were divided into three groups: the healthy control (G1) group, the infected control (G2) group, and the treated oocyst-infected (G3) group. The rabbits were sacrificed 43 days post-infection (dpi). The infectivity of the oocysts was assessed. The treated oocyst-infected rabbits exhibited slight abdominal distension and dullness symptoms. The G3 group had no oocyst output, with a 100% reduction from 41 dpi until the end of the experiment. Immunologically, the IgG level of the G2 group gradually increased (p ≤ 0.05) much more than that of the G3 group. The IL-12 level in the G3 group significantly increased from 16 dpi until the end of the experiment, nearly reaching the level in healthy animals. Decreased CD4+ and CD8+ immunolabelling was observed in the liver sections of the group infected with the alginate propolis NP-treated oocysts, and there was a remarkable improvement in the histopathological parameters.

CONCLUSIONS

These data indicate that Alg propolis NPs are sufficient to reduce the infectivity of E. stiedae oocysts.

Overexpression of Eimeria tenella Rhoptry Kinase 2 Induces Early Production of Schizonts

Eimeria tenella is an obligate intracellular parasite responsible for avian coccidiosis. Like other apicomplexan parasites, such as Toxoplasma gondii, cell invasion and intracellular development rely on apical organelle content discharge, named micronemes and rhoptries. Some rhoptry (ROP) kinases (ROPK) are key virulence factors in T. gondii. To date, among the 28 ropk genes carried by E. tenella, only two to four were confirmed by proteomic analysis or immunostaining to be expressed at the sporozoite stage. We have previously shown that EtROP1 is implicated in the inhibition of host cell apoptosis by interacting with the cellular p53. This work functionally described the second ROP kinase expressed at the sporozoite stage in E. tenella. EtROP2 is an active kinase that phosphorylates cell substrates of approximately 50 kDa. Its overexpression leads to the shortening of the prepatent period and to the early development of first-generation schizonts. Conduction of RNA sequencing analysis and reverse transcriptase quantitative PCR (RT-qPCR) on the host cell allowed us to identify the mitogen-activated protein kinase (MAPK) pathway and the transcription factor cFos to be upregulated by EtROP2. We also showed by immunofluorescence assay that the active kinase EtROP2 is implicated in the p38 MAPK pathway activation. We established here that EtROP2 activates the p38 MAPK pathway through a direct or indirect phosphorylation, leading to the overexpression of the master transcription factor cFos known to be implicated in E. tenella development. IMPORTANCE Rhoptries are specialized secretory organelles found in zoite stages of apicomplexan parasites. In addition to well-conserved rhoptry neck proteins, their protein consists mostly of kinase proteins, highly divergent from eukaryotic kinases. Some of those kinases are described as major virulence factors in Toxoplasma gondii, secreted into the host cell to hijack signaling pathways. Most of those kinases remain to be characterized in Eimeria tenella. Deciphering their cellular function is a prerequisite to supporting their relevance as a druggable target in development of new means of Eimeria tenella control. Secreted divergent kinases that interact with host cell partners to modulate pathways are good candidates, as they coevolve with their host targets to ensure their function within the host and are less prone to mutations that would lead to drug resistance. The absence of any orthologous kinase in host cells makes these parasite kinases a promising drug target candidate.

Irradiated oocysts in combination with inulin adjuvant-induced potent immune responses against Eimeria tenella infection in broiler chickens

Coccidiosis is the leading parasitic disease in poultry. One of the most critical Eimeria species, Eimeria tenella, lives inside the cecal epithelial cells and induces bloody coccidiosis. The present study evaluated the effect of radiation-attenuated E. tenella oocytes mixed with inulin adjuvant on broiler chicken. Initially, the effect of irradiation on oocyst attenuation was confirmed. Then, one-day-old broilers (n = 90) were divided into nine groups on seven days of age as follow: Group 1 (400 attenuated oocysts + 1.00 mg of adjuvant), group 2 (400 attenuated oocysts + 0.50 mg adjuvant), group 3 (200 attenuated oocysts + 1.00 mg of adjuvant), group 4 (200 attenuated oocysts + 0.50 mg adjuvant), group 5 (1.00 mg adjuvant), group 6 (400 attenuated oocysts), group 7 (commercial vaccine), group 8 (negative control) and group 9 (blank). On day 21, we performed a challenge with E. tenella oocytes and investigated oocyst output and average weekly weight throughout the study. At the end of the study, we evaluated macroscopic lesion, histology, cytokine level and leukogram status. The results showed a statistically significant difference among groups. Furthermore, the optimal dose was 400 irradiated oocysts and 1.00 mg of inulin. Moreover, an X-ray could reduce the virulence of E. tenella oocytes. Inulin alone or combined with attenuated oocysts showed an acceptable effect on evaluated parameters.

Impact of Eimeria meleagrimitis and intermittent amprolium treatment on performance and the gut microbiome composition of Turkey poults

Introduction

Drug-sensitive live coccidiosis vaccines have been used to control coccidiosis and renew drug sensitivity in commercial chicken operations. However, only limited species coverage vaccines have been available for commercial turkey producers. This study aimed to assess the effect of an E. meleagrimitis vaccine candidate, with and without amprolium intervention, on performance and oocyst shedding. Additionally, the effect of vaccination, amprolium treatment, and E. meleagrimitis challenge on intestinal integrity and microbiome composition was evaluated.

Methods

Experimental groups included: (1) NC (non-vaccinated, non-challenged control); (2) PC (non-vaccinated, challenged control); (3) VX + Amprol (E. meleagrimitis candidate vaccine + amprolium); and 4) VX (E. meleagrimitis candidate vaccine). For VX groups, 50% of the direct poults were orally vaccinated at DOH with 50 sporulated E. meleagrimitis oocysts and were comingled with contact or non-vaccinated poults for the duration of the study. From d10-14, VX + Amprol group received amprolium (0.024%) in the drinking water. All groups except NC were orally challenged with 95K E. meleagrimitis sporulated oocysts/mL/poult at d23. At d29, ileal and cecal contents were collected for 16S rRNA gene-based microbiome analysis.

Results and Discussion

VX did not affect performance during the pre-challenge period. At d23-29 (post-challenge), VX groups had significantly (P < 0.05) higher BWG than the PC group. Contacts and directs of VX groups in LS had significantly reduced compared to PC. As anticipated, amprolium treatment markedly reduced fecal and litter OPG for the VX + Amprol group compared to the VX group which did not receive amprolium. The ileal and cecal content results showed that the PC group had different bacterial diversity and structure, including alpha and beta diversity, compared to NC. Linear discriminant analysis Effect Size (LEfSe) identified that Lactobacillus salivarius (ASV2) was enriched in PC's ileal and cecal content. Compared to NC and PC, the vaccinated groups showed no distinct clusters, but there were similarities in the ileal and cecal communities based on Bray-Curtis and Jaccard distances. In conclusion, these results indicate that vaccination with this strain of E. meleagrimitis, with or without amprolium intervention, caused a very mild infection that induced protective immunity and challenge markedly affected both the ileal and cecal microbiome.

Comparative Effect of Allicin and Alcoholic Garlic Extract on the Morphology and Infectivity of Eimeria tenella Oocysts in Chickens

Avian coccidiosis remains one of the major parasitic diseases that threaten the global poultry industry. Since prevention is superior to treatment, this study focuses on eliminating the infection outside the host. To determine their effect on the viability of Eimeria tenella oocysts in vitro, allicin and alcoholic garlic extract, which are natural, less toxic, and inexpensive products, were compared to KOH 5% (chemical disinfectant) using an in vitro culture system. Three concentrations of allicin (45, 90, and 180 mg/mL) and alcoholic garlic extract (90, 180, and 360 mg/mL, were used. Subsequently, destructive and sporulation-inhibiting effects on Eimeria oocysts were detected using light and electron microscopy. Young chickens were infected with treated sporulated oocysts to determine their effect on infectivity. After 7 days pi, the percentage of excreted oocysts (oocyst shedding) was determined, and the chickens were slaughtered for histopathological examination of the cecal tissues. Under an electron microscope, allicin at a concentration of 180 mg/mL and alcoholic garlic extract at a concentration of 360 mg/mL demonstrate a high oocysticidal activity with severe destruction of the oocyst wall and the appearance of pores. In addition, both concentrations directly affected the infectivity of sporulated oocysts by reducing the shedding of oocysts and the pathological lesions of infected young chickens. We concluded that the ability of Allicin and alcoholic garlic extract to eliminate Eimeria oocysts makes them superior to chemical disinfectants as a disinfectant.

Extracellular Vesicles in Veterinary Medicine

Extracellular vesicles (EVs) are cell-derived membrane-bound vesicles involved in many physiological and pathological processes not only in humans but also in all the organisms of the eukaryotic and prokaryotic kingdoms. EV shedding constitutes a fundamental universal mechanism of intra-kingdom and inter-kingdom intercellular communication. A tremendous increase of interest in EVs has therefore grown in the last decades, mainly in humans, but progressively also in animals, parasites, and bacteria. With the present review, we aim to summarize the current status of the EV research on domestic and wild animals, analyzing the content of scientific literature, including approximately 220 papers published between 1984 and 2021. Critical aspects evidenced through the veterinarian EV literature are discussed. Then, specific subsections describe details regarding EVs in physiology and pathophysiology, as biomarkers, and in therapy and vaccines. Further, the wide area of research related to animal milk-derived EVs is also presented in brief. The numerous studies on EVs related to parasites and parasitic diseases are excluded, deserving further specific attention. The literature shows that EVs are becoming increasingly addressed in veterinary studies and standardization in protocols and procedures is mandatory, as in human research, to maximize the knowledge and the possibility to exploit these naturally produced nanoparticles.

Toltrazuril and diclazuril: comparative evaluation of anti-coccidial drugs using a murine model

Intestinal coccidiosis caused by Eimeria protozoan species is an economically important disease, especially in poultry and cattle. Anti-coccidial drugs commonly used for controlling coccidiosis are toltrazuril (TTZ) and diclazuril (DCZ). In this study, the efficacies of TTZ and DCZ were compared using a murine model, and the effect of these treatments on the induction of acquired resistance was evaluated. Male C57BL/6J mice were inoculated with 1,000 sporulated E. vermiformis oocytes and treated with TTZ or DCZ. The recommended TTZ dose for cattle (15 mg/kg) completely prevented oocyte excretion. But, mice required 5 mg/kg of DCZ, which is five times the recommended dose for cattle, to reduce oocyte excretion. In E. vermiformis re-infection, TTZ (15 mg/kg) and DCZ (5 mg/kg) treatments did not interfere with the development of acquired resistance. Bodyweight gain was significantly higher in the TTZ-treated group than in the control (untreated/infected) group and the DCZ-treated group, and no significant difference in bodyweight gain was observed between the TTZ-treated group and the healthy (uninfected/untreated) group. Analysis of T lymphocyte subsets in the spleen and mesenteric lymph nodes indicated that the relative populations of CD4+ and CD8+ T cells were reduced in the DCZ-treated and control (untreated/infected) groups, suggesting there was immunosuppression during the infection. However, no reductions in T cell populations were observed in the TTZ-treated group. The results indicated that an optimal anti-coccidial drug is one that can completely break the parasite life cycle in the host animal.

Coccidiostats and Poultry: A Comprehensive Review and Current Legislation

Coccidiosis remains one of the major problems of the poultry industry. Caused by Eimeria species, Coccidiosis is a contagious parasitic disease affecting poultry with great economic significance. Currently, in order to prevent health problems caused by this disease, broiler farmers make extensive use of coccidiostats in poultry feed, maintaining animal health and, in some cases, enhancing feed conversion. The presence of unauthorized substances, residues of veterinary products and chemical contaminants in the food industry is of concern, since they may pose a risk to public health. As the use of coccidiostats has been increasing without any requirements for veterinary prescription, research and surveillance of coccidiostat residues in poultry meat is becoming imperative. This review presents an up-to-date comprehensive discussion of the state of the art regarding coccidiosis, the most used anticoccidials in poultry production, their mode of action, their prophylactic use, occurrence and the European Union (EU) applicable legislation.

Chemical and Pharmacological Properties of Decoquinate: A Review of Its Pharmaceutical Potential and Future Perspectives

Decoquinate (DQ) is an antimicrobial agent commonly used as a feed additive for birds for human consumption. Its use as an additive is well established, but DQ has the potential for therapy as an antimicrobial drug for veterinary treatment and its optimized derivatives and/or formulations, mainly nanoformulations, have antimicrobial activity against pathogens that infect humans. However, DQ has a high partition coefficient and low solubility in aqueous fluids, and these biopharmaceutical properties have limited its use in humans. In this review, we highlight the antimicrobial activity and pharmacokinetic properties of DQ and highlight the solutions currently under investigation to overcome these drawbacks. A literature search was conducted focusing on the use of decoquinate against various infectious diseases in humans and animals. The search was conducted in several databases, including scientific and patent databases. Pharmaceutical nanotechnology and medicinal chemistry are the tools of choice to achieve human applications, and most of these applications have been able to improve the biopharmaceutical properties and pharmacokinetic profile of DQ. Based on the results presented here, DQ prototypes could be tested in clinical trials for human application in the coming years.

Coccidiosis: Recent Progress in Host Immunity and Alternatives to Antibiotic Strategies

Coccidiosis is an avian intestinal disease caused by several distinct species of Eimeria parasites that damage the host’s intestinal system, resulting in poor nutrition absorption, reduced growth, and often death. Increasing evidence from recent studies indicates that immune-based strategies such as the use of recombinant vaccines and various dietary immunomodulating feed additives can improve host defense against intracellular parasitism and reduce intestinal damage due to inflammatory responses induced by parasites. Therefore, a comprehensive understanding of the complex interactions between the host immune system, gut microbiota, enteroendocrine system, and parasites that contribute to the outcome of coccidiosis is necessary to develop logical strategies to control coccidiosis in the post-antibiotic era. Most important for vaccine development is the need to understand the protective role of the local intestinal immune response and the identification of various effector molecules which mediate anti-coccidial activity against intracellular parasites. This review summarizes the current understanding of the host immune response to coccidiosis in poultry and discusses various non-antibiotic strategies which are being developed for coccidiosis control. A better understanding of the basic immunobiology of pertinent host–parasite interactions in avian coccidiosis will facilitate the development of effective anti-Eimeria strategies to mitigate the negative effects of coccidiosis.

Chicken Coccidiosis: From the Parasite Lifecycle to Control of the Disease

The poultry industry is one of the main providers of protein for the world's population, but it faces great challenges including coccidiosis, one of the diseases with the most impact on productive performance. Coccidiosis is caused by protozoan parasites of the genus Eimeria, which are a group of monoxenous obligate intracellular parasites. Seven species of this genus can affect chickens (Gallus gallus), each with different pathogenic characteristics and targeting a specific intestinal location. Eimeria alters the function of the intestinal tract, generating deficiencies in the absorption of nutrients and lowering productive performance, leading to economic losses. The objective of this manuscript is to review basic concepts of coccidiosis, the different Eimeria species that infect chickens, their life cycle, and the most sustainable and holistic methods available to control the disease.

Genotype-environment interaction in layer chickens in the growing stage: comparison of three genotypes at two different feeding levels with or without red mite (Dermanyssus gallinae) infestation

This study investigated how early growth was affected in various chicken genotypes, which were fed ad libitum or restricted and with or without poultry red mite (PRM) infestation. Atak-S (AS), New Hampshire Red (NHR), and Light Sussex (LS) genotypes were used in the study. In total, 120 chicks were used from each genotype. Four groups were formed: feed-restricted (FR) and infested with parasite (P + ), FR only, fed ad libitum and P + , and fed ad libitum only. Feed restriction was applied as 20 % of the feed consumption of the group fed ad libitum the day before for each genotype. The study was conducted between 2 to 12 weeks of age. Weekly live weights and feed consumption were recorded, and the feed conversion ratio was calculated. Traps were placed in cages to count parasites. Regarding the live weight, NHR tolerated the PRM infestation in the ad libitum feed conditions better than other genotypes. While the infested NHR and AS birds had lower live weights than the non-infested ones under FR conditions, there was no difference between infested and non-infested birds of NHR and AS genotypes when they fed ad libitum. The feed consumption of infested AS and NHR birds was higher than that of non-infested counterparts when fed ad libitum. By contrast, the LS chicks consumed less food in the infested environment. In conclusion, the genotypes responded differently to PRM infestation in different feeding environments.

Prevalence of Eimeria sp. in Broiler Poultry Houses with Positive and Negative Pressure Ventilation Systems in Southern Brazil

Coccidiosis is an enteric disease caused by protozoa of the Eimeria genus and is of great economic relevance in industrial aviculture. The objective of this work was to determine the prevalence of Eimeria sp. in broiler poultry houses with positive (System 1) and negative (System 2) pressure ventilation and assess the associated factors. A transversal study was conducted using 8 random broiler chickens from 64 houses (n = 512) and macroscopic and histologic evaluation of the intestines, as well as PCR for Eimeria sp. The prevalence of Eimeria sp. was 90.6% (95% confidence interval [CI]: 97.8-83.5), with 93.8% (95% CI: 100-85.4) in System 1 and 87.5% (95% CI: 99.0-76.0) in System 2. The most prevalent species was Eimeria acervulina, and the most common combination was Eimeria acervulina, Eimeria maxima, and Eimeria tenella. System 2 and the negative Eimeria subgroup showed the best results for feed conversion and daily weight gain. By evaluating litter treatment, we found that quicklime reduced the risk of presence of Eimeria maxima and Eimeria tenella. In conclusion, Eimeria sp. had a high prevalence in both systems, with a predominance of mixed infections. System 2 and negative flocks showed the best zootechnical results.

Exogenous Enzymes Influenced Eimeria-Induced Changes in Cecal Fermentation Profile and Gene Expression of Nutrient Transporters in Broiler Chickens

Two 21-day experiments were conducted to investigate the effects of exogenous enzymes on growth performance, tight junctions, and nutrient transporters, jejunal oligosaccharides and cecal short-chain fatty acids (SCFA) of broiler chickens challenged with mixed Eimeria. Two different basal diets: high fiber-adequate protein (HFAP; Expt. 1) or low fiber-low protein (LFLP; Expt. 2) were used in the two experiments. In each experiment, birds were allocated to four treatments in a 2 × 2 factorial arrangement (with or without protease and xylanase combination; with or without Eimeria challenge). In Expt. 1, with HFAP diets, Eimeria upregulated (p < 0.05) the expression of claudin-1, but downregulated (p < 0.05) glucose transporters GLUT2/GLUT5. On the contrary, enzymes downregulated (p < 0.05) claudin-1 and alleviated the Eimeria-depressed GLUT2/GLUT5 expression. In both experiments, Eimeria decreased (p < 0.05) cecal saccharolytic SCFA and increased (p < 0.05) cecal branched-chain fatty acids. The challenge × enzyme interaction (p < 0.05) showed that enzymes reversed the Eimeria effects on fermentation pattern shift. In conclusion, Eimeria altered tight junctions and nutrient transporters expression promoted cecal proteolytic fermentation and inhibited saccharolytic fermentation. Exogenous enzymes showed the potential of alleviating the Eimeria-induced intestinal gene expression changes and reversing the unfavorable cecal fermentation pattern.

Curcumin reduces enteric isoprostane 8-iso-PGF2α and prostaglandin GF2α in specific pathogen-free Leghorn chickens challenged with Eimeria maxima

The purpose of this pilot study was to evaluate and determine the concentration of prostaglandin GF2α (PGF2α) and isoprostane 8‐iso‐PGF2α in plasma and intestine of specific pathogen-free (SPF) Leghorn chickens challenged with Eimeria maxima, with or without dietary supplementation of curcumin using solid‐phase microextraction and ultra‐performance liquid chromatography/tandem mass spectrometry. Eighty 1-day-old male SPF chickens were randomly allocated to one of four groups with four replicates (n = 5 chickens/replicate). Groups consisted of: (1) Control (no challenge), (2) Curcumin (no challenge), (3) Eimeria maxima (challenge), and (4) Eimeria maxima (challenge) + curcumin. At day 28 of age, all chickens in the challenge groups were orally gavaged with 40,000 sporulated E. maxima oocysts. No significant differences (P > 0.05) were observed in the groups regardless of the treatment or challenge with E. maxima. Enteric levels of both isoprostane 8‐iso‐PGF2α and PGF2α at 7 days and 9 days post-challenge were significantly increased (P < 0.01) compared to the non-challenge control chickens. Interestingly, the enteric levels of both isoprostane 8‐iso‐PGF2α and PGF2α at 7 days post-challenge were significantly reduced in chickens fed curcumin, compared to control chickens challenge with E. maxima. At 9 days post-challenge, only levels of isoprostane 8‐iso‐PGF2α in the enteric samples were significantly reduced in chickens challenged with E. maxima supplemented with curcumin, compared with E. maxima challenge chickens. No differences of isoprostane 8‐iso‐PGF2α or PGF2α were observed in plasma at both days of evaluation. Similarly, no significant differences were observed between the challenge control or chickens challenge with E. maxima and supplemented with curcumin at both times of evaluation. The results of this pilot study suggests that the antioxidant anti-inflammatory properties of curcumin reduced the oxidative damage and subsequent intestinal mucosal over-production of lipid oxidation products. Further studies to confirm and extend these results in broiler chickens are required.

Actin-depolymerizing factor from Eimeria tenella promotes immunogenic function of chicken dendritic cells

Dendritic cells play a crucial role in inducing antigen-specific immunity to pathogens. During host-parasite interaction, host immune response to the parasite molecules is considered essential for recognizing novel antigens for control strategies. Therefore, in the present study, chicken dendritic cells (DCs) (ChDCs), derived from spleens were used to evaluate their capacity to proliferate and differentiate autologous T lymphocytes in response to actin-depolymerizing factor from Eimeria tenella (EtADF). Immunoblot analysis showed that recombinant EtADF protein (rEtADF) was able to interact with rat anti-rEtADF antibodies. The immunofluorescence test confirmed rEtADF binding on ChDCs surface. Flow cytometric analysis revealed that phenotypes for MHCII, CD1.1, CD11c, CD80, and CD86 were increased in ChDCs after rEtADF treatment. qRT-PCR results indicated that ChDCs triggered TLR signaling in response to rEtADF, and suppressed Wnt signaling. Transcript levels of CD83, CCL5, and CCR7 in ChDCs were improved following rEtADF treatment. In addition, rEtADF promoted DC-directed T cell proliferation and differentiation of naïve T cells into CD3⁺/CD4⁺ T cells in DC/T cell co-incubation system. Cytokine analysis of rEtADF-pulsed ChDCs showed increased levels of IL-12 and IFN-γ, while IL-10 and TGF-β remained unchanged. Moreover, rEtADF-treated ChDCs enhanced production of IFN-γ when incubated with T cells, and IL-4 secretion remained unchanged. Our findings indicted that rEtADF could facilitate the polarization of Th1 immune cells by triggering both host DCs and T cells. Our findings provide useful insights into future work aimed at anticoccidial vaccine strategies.

Concurrent use of saponins and live coccidiosis vaccines: the influence of a quillaja and yucca combination on anticoccidial effects and performance results of coccidia-vaccinated broilers

A series of studies was conducted to determine the effects of a quillaja and yucca (saponin) combination (QY) product on postvaccination oocyst production, development of coccidial immunity, and final bird performance of broilers administered live coccidiosis vaccines. In all, 3 groups of tests were carried out. Study 1 evaluated the effects of QY (0 and 250 ppm) on oocyst per gram of feces (OPG) following vaccination at day-of-age; OPG were measured from 5 to 12 d postvaccination. Study 2 determined the effects of QY (250 ppm) in the presence of 3 commercial coccidiosis vaccines in floor pens. OPG were measured weekly for birds receiving each vaccine and for each corresponding vaccine group fed QY. To determine whether QY influenced the development of coccidial immunity induced by the 3 vaccines, 5 birds were removed from each pen at 28 d and challenged with pathogenic levels of Eimeria spp. At 6 d post challenge, lesion scores were used to evaluate the effects of QY on immune protection provided by each vaccine. In addition, comparisons of final bird performance were made between birds given each vaccine and their corresponding vaccinates fed QY. Study 3 comprised a meta-analysis of 15 floor pen trials in which 21- and 42-d body weight, feed conversions, and total mortality were compared between coccidiosis-vaccinated broilers and similarly vaccinated broilers fed QY (250 ppm). Results of these experiments indicated that feeding QY to vaccinated broilers did not significantly affect OPG from days 5 through 12 postvaccination (P > 0.05). For each vaccine tested in study 2, OPG values were the highest at 14 and 21 d postvaccination. QY significantly reduced OPG at 14 d postvaccination for 2 of the vaccines tested, and produced a similar effect in 1 vaccine at 21 d postvaccination. The remaining vaccine was not affected by QY in the postvaccination OPG results. Despite these changes in OPG, significant differences in lesion scores following the Eimeria challenge were not observed for any vaccinated groups receiving QY. Irrespective of the vaccine, both interim and final feed conversion values were significantly improved when QY was fed (P < 0.01). Similarly, results of a 15-trial meta-analysis indicated that QY-fed vaccinated broilers had higher body weights, improved feed conversions, and lower mortality than their vaccinated controls. Results show that while QY may induce changes in OPG following vaccination, coccidia-vaccinated broilers fed QY develop immunity equivalent to that of controls and show significant improvements in performance and mortality.

Evaluation of nitro compounds as feed additives in diets of Eimeria-challenged broilers in vitro and in vivo

Coccidiosis is a disease caused by Eimeria spp., resulting in approximately 3 billion US dollar loss in the poultry industry annually. The present study evaluated the effects of potential feed additives, 2-Nitro-1-propanol (NP) and nitroethanol (NE), on control of coccidiosis. An in vitro experiment indicated that both NP and NE inhibited the development of sporozoites in Madin-Darby bovine kidney cells (MDBK). The in vivo study was further conducted to evaluate the effects of NP and NE on growth performance, nitrogen-corrected apparent metabolizable energy (AMEn), and intestinal lesion scores of broilers challenged with Eimeria spps. Six treatments were tested in the study, including the nonchallenged control, challenged control, 100 ppm NP, 200 ppm NP, 100 ppm NE, and 200 ppm NE. Broilers were fed the treatment diets from day 12 until the end of the trial. All birds except the unchallenged control were challenged with Eimeria maxima, Eimeria tenella, and Eimeria acervulina on day 14. The growth performance was calculated, and the intestinal lesion was scored on day 20. The results showed that Eimeria challenge significantly reduced growth performance, increased intestinal lesion scores, and decreased AMEn compared with the nonchallenged control group. Birds fed with 200 ppm of NP had reduced growth performance compared with the nonchallenged control and challenged control. However, the supplementation of NP significantly improved AMEn and reduced cecal damage. Overall, NP and NE reduced sporozoites numbers in the MDBK cells. NP improved dietary digestibility of energy and reduces lesion scores in the ceca but could not maintain growth performance in broiler chickens infected with Eimeria spp.

Utility of Feed Enzymes and Yeast Derivatives in Ameliorating Deleterious Effects of Coccidiosis on Intestinal Health and Function in Broiler Chickens

Coccidiosis induced necrotic lesions impair digestive capacity and barrier function in concurrence with increased risks for secondary bacterial infections. The industry has been successful in controlling coccidiosis with anticoccidials and vaccination. However, concerns over Eimeria species resistant to anticoccidials, gaps in vaccination and restriction on antibiotics is stimulating research and application of alternative and/or complimentary strategies for coccidiosis control. The aim of this paper is to appraise literature on the utility of feed enzymes and yeast derivatives in modulating coccidiosis. Feed enzymes can complement endogenous enzymes (protease, amylase, and lipase) that may become insufficient in coccidiosis afflicted birds. Coccidiosis in the upper small intestine creates conditions that enhances efficacy of phytase and there are reports indicating supplemental phytase can mitigate the negative impact of coccidiosis on bone quality. Increase in intestinal short chain fatty acids due supplemental fiber degrading enzymes has been linked with reduced survivability of Eimeria. There is evidence whole yeast (live or dead) and derivatives can modulate coccidiosis. Immunomudulation properties of the yeast derivatives have been shown to enhance cellular and humoral immunity in Eimeria challenge models which is critical for effectiveness of coccidial vaccination. Moreover, yeast nucleotides have been shown to be beneficial in stimulating healing of intestinal mucosal surface. Other novel work has shown that certain yeast cells can produce derivatives with anticoccidial compounds effective in attenuating oocysts shedding. Yeast cell surface has also been shown to be an effective oral Eimeria vaccine delivery vehicle. Overall, while further refinement research is warranted to address inconsistencies in responses and commercial application, there is evidence feed enzymes and yeast derivatives could complement strategies for maintaining intestinal function to bolster growth performance in broilers compromised with coccidiosis. However, broilers receive diets containing several feed additives with distinct mode of actions and yet there is dearth of empirical data on the expected responses.Future evaluations should consider combinations of additives to document animal responses and potential synergies.