Effect of subcutaneously administered diclazuril on the output of Eimeria species oocysts by experimentally infected rabbits

Changes of oxidant-antioxidant parameters in small intestines from rabbits infected with E. intestinalis and E. magna

Rabbit coccidiosis is a very serious disease caused by protozoan parasites of the genus Eimeria, which increases the production rate of free radicals, especially reactive oxygen species. When the generation of free radicals exceeds the scavenging capacity of the body’s antioxidant system, the oxidant-antioxidant balance is broken, resulting in oxidative stress. This study was designed to investigate the effect on the oxidant-antioxidant status of rabbits infected with E. intestinalis and E. magna. To this end, eighteen 30-d-old weaned rabbits were randomly allocated into three groups as follows: the E. intestinalis infection group with 3×103 sporulated oocysts of E. intestinalis, the E. magna infection group with 20×103 sporulated oocysts of E. magna, and the uninfected control group. We measured the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC) and the contents of malondialdehyde (MDA) in rabbits’ small intestinal tissues (duodenum, jejunum and ileum) of the three groupson day 8. The results showed that CAT activity and MDA levels significantly increased, while the activities of SOD, GSH-Px and T-AOC decreased after E. intestinalis and E. magna infection. Besides, the jejunum and ileum were particularly damaged in the rabbits. It is concluded that the pathological oxidative stress occurs during the E. intestinalis and E. magna infection process and the body’s oxidant-antioxidant balance is disrupted.

Pharmacokinetics of toltrazuril and its metabolites after oral and parenteral administration of novel oil-based suspension based on micro-environmental pH-modifying solid dispersion in rabbits

Toltrazuril (TOL) is a broad-spectrum anticoccidial drug which is widely used in poultry and livestock. A novel oral suspension based on soybean oil-based TOL micro-environmental pH-modifying solid dispersion (micro pHm SD) and a novel injectable suspension based on white oil-based TOL micro pHm SD were developed, showing high physicochemical stability and high drug release in vitro with good histocompatibility. The present study is to evaluate the pharmacokinetic profiles of TOL and its major metabolites, e.g. toltrazuril sulfoxide (TOLSO) and toltrazuril sulfone (TOLSO₂) in rabbits following oral or subcutaneous administration with these two TOL SD suspensions. The plasma concentrations of TOL, TOLSO and TOLSO₂ were determined by high performance liquid chromatography (HPLC). Plasma concentration-time data were analyzed by a non-compartmental model analysis. The soybean oil-based TOL suspension after single oral administration at 20 mg/kg body weight (bw) significantly increased the plasma concentrations of TOL, TOLSO and TOLSO₂ compared with Baycox® 5 % suspension. Following subcutaneous administration of the white oil-based TOL suspension (20 mg/kg bw), TOL was well absorbed and metabolized more slowly to TOLSO and TOLSO₂, compared with oral administration, resulting in the significantly prolonged residence time in rabbits. The two suspensions significantly improved the relative bioavailability of TOL and its two metabolites, showing their potential usage in the control of coccidian in poultry and livestock.

Deaths Due to Mixed Infections with Passalurus ambiguus, Eimeria spp. and Cyniclomyces guttulatus in an Industrial Rabbit Farm in Greece

Domestic rabbits are commercially farmed for their meat whilst gastrointestinal diseases can hinder their production. Passalurusambiguus and Eimeria spp. are two common rabbit intestinal parasites that can cause diarrhoea, among other symptoms, and in severe cases, death. C. guttulatus is a commensal yeast of the rabbits’ stomach that is considered apathogenic but can worsen symptoms in rabbits suffering from coccidiosis. In the present case report, we describe an outbreak of deaths in three different age groups (A: lactating does, B: 58 days old and C: 80 days old) in an industrial rabbit farm in Greece. Symptoms included depression, diarrhoea, inappetence, weight loss, dehydration and ruffled furs. Using a faecal flotation technique, sick rabbits were found to be moderately to heavily infected with P. ambiguus, Eimeria spp. and C. guttulatus. Treatment with fenbendazole and oregano oil combined with hygiene control measures successfully controlled the infections and resolved clinical symptoms. A faecal flotation method or other reliable diagnostic technique should be used regularly in industrial rabbit farms to screen for gastrointestinal parasitic infections. Early diagnosis and control will help to maintain production levels and, therefore, limit financial losses for the farmer while ensuring animal welfare.

Efficacy of Sulphachloropyrazine, Amprolium Hydrochloride, Trimethoprim-Sulphamethoxazole, and Diclazuril against Experimental and Natural Rabbit Coccidiosis

There are no anticoccidial drugs labelled for rabbits in Kenya and those available are used as extra labels from poultry. The drugs are used in rabbits with limited knowledge of their efficacy and safety. The aim of this study was to determine the efficacy of sulphachloropyrazine, amprolium hydrochloride, and trimethoprim-sulphamethoxazole relative to diclazuril when used curatively against experimental and natural rabbit coccidiosis. In a controlled laboratory trial, sixty (60) rabbits were randomly allocated to six treatment groups, namely, 1A, 2B, 3C, 4D, 5E, and 6F, each with 10 rabbits. Groups 2B, 3C, 4D, 5E, and 6F were experimentally infected with mixed Eimeria species while group 1A served as uninfected-untreated (negative) control group. Four of the infected groups were treated with sulphachloropyrazine (5E), amprolium hydrochloride (2B), trimethoprim-sulphamethoxazole (6F), and diclazuril (4D) using dosages recommended by manufacturers. Group 3C served as infected-untreated (positive) control. A field efficacy trial in naturally infected rabbits was then undertaken. The results revealed that sulphachloropyrazine and diclazuril were effective against rabbit clinical coccidiosis by significantly reducing oocyst counts from 149.00±110.39 x 10⁴ to 3.31±0.86 x 10⁴ Eimeria spp. oocysts per gram of feces (opg) and 59.70±12.35 x 10⁴ to 0.0±0.0 x 10⁴ opg, respectively, in the laboratory trial. Similarly, sulphachloropyrazine and diclazuril recorded reduced oocyst counts in the field trial from 280.33±44.67 x 10³ to 0.44±0.14 x 10³ opg and 473.44±176.01 x 10³ to 0.0±0.0 x 10³ opg, respectively. Still, sulphachloropyrazine and diclazuril showed superior efficacy by registering lesion scores and fecal scores close to those of uninfected untreated control group. Trimethoprim-sulphamethoxazole recorded a satisfactory efficacy in the field trial by recording reduced oocyst counts from 266.78±37.03 x 10³ to 0.75±0.11 x 10³ opg but was not efficacious in the laboratory trial. Amprolium hydrochloride was not efficacious against clinical coccidiosis in both the experimental and field trials.

The hydroxypropyl-β-cyclodextrin complexation of toltrazuril for enhancing bioavailability

Introduction

Toltrazuril (Tol) is used to prevent and combat coccidiosis. However, its low aqueous solubility and poor oral bioavailability limit clinical application.

Methods

To overcome the shortcomings, toltrazuril–hydroxypropyl–β-cyclodextrin inclusion complex (Tol-HP-β-CD) was prepared and characterized. The comparative plasma disposition kinetics of Tol was analyzed after a single orally administered dose of 10 mg/kg Tol or Tol-HP-β-CD in rabbits. Solution-stirring method was selected to prepare the inclusion complex. Complex formation was characterized by thin-layer chromatography, Fourier transform infrared spectrophotometry, and ¹H nuclear magnetic resonance spectroscopy. In plasma profile, plasma samples were collected between 1 and 10 days following administration. Plasma Tol concentrations were determined by high-performance liquid chromatography.

Results

In rabbit plasma, the time to peak concentration (T_max) of Tol-HP-β-CD was shorter than that of Tol (12 h vs 24 h). C_max (19.92±1.02 μg/mL) and area under the concentration–time curve (AUC0-∞, 1,176.86±70.26 mg/L h) of the Tol-HP-β-CD group significantly increased (p,0.01) than those of the Tol group (C_max, 8.02±1.04 μg/mL; AUC0-∞, 514.03±66.65 mg/L h).

Conclusion

It can be concluded that the Tol-HP-β-CD increased the aqueous solubility and enhanced the oral bioavailability in rabbits. Complexation with HP-β-CD is a feasible way to prepare a rapidly absorbed and more bioavailable Tol oral product.

Survey of coccidial infection of rabbits in Sichuan Province, Southwest China

Coccidiosis is a challenging disease of wild and domestic rabbits both, caused by Eimeria and thereby leads enormous economic losses at rabbit farms. The present study carried out to survey the prevalence and intensity of coccidial infection among the rabbits in Sichuan Province, southwest China. A total of 110 faecal samples were collected from 11 farms situated in eight main rabbits rearing administrative regions. Oocysts in faecal samples were purified, sporulated and identified according to morphological features. The overall prevalence of infection was 56.4 % (62/110), with prevalence of 64 % (47/75) for local meat breeds of rabbit and 51.4 % (18/35) for Rex Rabbits (local fur rabbits). Weanling rabbits had the highest prevalence (74 %, 37/50), followed by young rabbits (45 %, 13/29) and the adult rabbits showed the lowest prevalence (42 %, 13/31). Concurrent infection with two to seven Eimeria species was found. In total, 9 species of Eimeria were identified from oocyst-positive samples. E. perforans was the most prevalent specie (42.73 %), followed in order by Eimiera media, E. irresidua, E. magna, and E. intestinalis with prevalences of 35.45, 34.55, 31.82, and 23.64 %, respectively. Results of the present investigation indicated that the prevalence of coccidial infection is high among the rabbit population in southwest China. This study also elucidate about the coccidial infection and emphasis to adopt control strategies in commercial rabbitories.

Receptor for activated C kinase ortholog of second-generation merozoite in Eimeria tenella: clone, characterization, and diclazuril-induced mRNA expression

The receptor for activated C kinase (RACK) cDNA of second-generation merozoites of Eimeria tenella was cloned using reverse transcriptase polymerase chain reaction and rapid amplification of cDNA ends, compared with other species, and then successfully expressed using the pET-28a vector in Escherichia coli BL21 (DE3) (EtRACK). Nucleotide sequence analysis revealed that the full length of the cloned cDNA (1,264 bp) encompassed a 957-bp open reading frame encoding a polypeptide of 318 residues with an estimated molecular mass of 34.94 kDa and a theoretical isoelectric point of 5.97. Molecular analysis of EtRACK reveals the presence of seven WD40 repeat motifs. EtRACK localizes to the cytoplasm and nucleus in second-generation merozoites of E. tenella. The cDNA sequence has been submitted to the GenBank Database with accession number JQ292804. EtRACK shared 98% homology with the published sequence of a RACK protein from Toxoplasma gondii at the amino acid level (GenBank XP_002370996.1). Recombinant protein expression was induced using 1 mM of isopropyl β-D-1-thiogalactopyranoside in vitro at 30 °C. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed that the 39.79-kDa fusion protein existed in unsolvable form. Quantitative real-time PCR analysis showed that compared with the control group, the level of EtRACK mRNA expression in the treatment group was downregulated by 81.3% by diclazuril treatment. The high similarity of EtRACK to previously described RACKs of other organisms, as well as its downregulated expression in second-generation merozoites induced by diclazuril, suggests that it could play a key role in the signaling event that precedes protein secretion and parasite invasion. Moreover, the downregulation of EtRACK mRNA expression also enriches studies on the mechanism of action of diclazuril on E. tenella.

Large-scale survey of the prevalence of Eimeria infections in domestic rabbits in China

The current study examined the prevalence of Eimeria infections in domestic rabbits in China. A total of 480 faecal samples were collected from 48 farms in 14 provinces of China. Each faecal sample was subjected to oocyst counting and oocyst isolation. The Eimeria species from samples containing isolated and sporulated oocysts were morphologically identified under microscope. The overall prevalence of infections was 41.9% (201/480). Northwest China had the highest prevalence (70%), followed closely by Northeast China (65%) and Southwest China (62.5%). The prevalences in North China (34%) and South China (25.8%) were significantly lower. The large and medium farms had lower prevalences (34.2% and 37.2%, respectively) than the small farms (61.4%). Coccidian oocysts were found in 42.2% (76/180) of faecal samples from meat rabbits, 40% (28/70) from angora rabbits and 44.7% (85/190) from Rex rabbit. In total, ten species of Eimeria were identified from oocyst-positive samples. Concurrent infection with two to eight Eimeria species was found. E. perforans was the most prevalent species (35.2%), followed in order by E. media, E. magna, E. irresidua and E. intestinalis with prevalences of 31.3%, 28.8%, 19.4%, and 14.8%, respectively. Taken together, These results reveal the characteristics of the prevelance of rabbit coccidia infection in China, including the distribution, the scale of farming and the species, which are indispensable to the control of rabbits coccidiosis in China.

Comparison of toltrazuril and sulphadimethoxine in the treatment of intestinal coccidiosis in pet rabbits

Treatment of intestinal coccidiosis was studied in domestic pet rabbits. In 45 rabbits aged four months or more, coccidial oocysts were observed in the faeces of 35 rabbits at a mean density of 806 opg (range 50 to 6800 opg). Eimeria magna was the dominant species, with Eimeria media and Eimeria intestinalis also being common. The presence of the hepatic species Eimeria stiedae was not recorded. A single oral dose of 2.5 mg/kg or 5.0 mg/kg toltrazuril, or a single oral dose of 50 mg/kg sulphadimethoxine followed by its inclusion in drinking water at 1 g/4 l for nine days, were all found to significantly reduce the faecal oocyst count by 73 to 99 per cent. The extent of oocyst reduction in the faeces was not dependent on the dose of toltrazuril. Oocyst counts began to rise again in the days after treatment ceased.