Coccidiosis In Rabbits Research Articles

Progressive light microscopic changes in chronic recurrent outbreaks of hepatic coccidiosis in domestic rabbits

Hepatic coccidiosis is an important economic disease of rabbits. The progressive histopathological changes in liver of rabbits infected with Eimeria stiedae in chronic recurrent outbreaks of coccidiosis in organized rabbitries are discussed. One hundred and fifty morbid specimens of rabbit liversamples from known cases of hepatic coccidiosis preserved in 10% formalin were studied. The hepatic parenchyma revealed multifocal areas of coagulative to liquefactive necrosis, congestion, haemorrhages and vacuolar degenerative changes in hepatocytes along with periportal infiltration of numerous lymphocytes and a few neutrophils. Biliary ducts were hyperplastic with pappilomatous ingrowths of epithelium into lumen. In chronic infections, multifocal areas of severe periportal cirrhosis with islands of hepatic parenchyma were seen along with extensive infiltration of lymphocytes, plasma cells and macrophages and prominent calcification of bile ducts. Gall bladder epithelium also showed early lesions of hyperplasia of epithelial cells in mucosa with necrosis and severe inflammation and extensive fibrosis. The intensive growing conditions and contributory factors like high humidity, moisture, feeding and manure disposal system may lead to recurrent outbreaks of hepatic coccidiosis in rabbits.

Potential of wormwood (Artemisia absinthium) as a feed supplement in rabbit diet: effect on controlling rabbit coccidiosis, antioxidative systems and growth performance

Potential of wormwood (Artemisia absinthium) as a feed supplement in rabbit diet: effect on controlling rabbit coccidiosis, antioxidative systems and growth performance

A new species of Eimeria (Apicomplexa: Eimeriidae) from Californian rabbits in Hebei Province, China

Rabbit coccidiosis is caused by infection with one or usually several Eimeria species, parasitizing in hepatobiliary ducts or intestinal epithelium of rabbits. To date, 11 species of rabbit coccidia have been well documented. Here we report a new species of Eimeria from rabbits. Sporulated oocysts were ellipsoidal to slightly ovoidal, 37.4 (32.6–41.2) μm in length, 23.5 (20.9–25.5) μm in width, with a shape index (length/width) 1.6 (1.43–1.91) and smooth, bilayered, homogeneously thick wall. The micropyle was obvious and with an inner diameter of 6.2 (5.0–7.5) μm. Both oocyst residuum and polar granule were absent. Sporocysts were ellipsoidal to elongate, 17.2 (13.2–20.0) μm long and 8.4 (7.5–9.1) μm wide, with a shape index (length/width) of 2.1 (1.74–2.21) and the presence of Stieda body and sporocyst residuum. The prepatent period was 132h. Phylogenetic analysis showed that 18S rDNA sequence of the new species clustered together with the 11 rabbit Eimeria species into a clade. However, ITS-1 sequence of the new species shared low similarities (27.1%–30%) with those of 11 rabbit Eimeria species. As the data above supported the erection of a new species, we named it as Eimeria kongi n. sp., in honor of Fanyao Kong, a Chinese parasitologist. The finding of the new species has important implications for the diagnosis and prevention of rabbit coccidiosis.

Potential Vaccine Targets against Rabbit Coccidiosis by Immunoproteomic Analysis.

The aim of this study was to identify antigens for a vaccine or drug target to control rabbit coccidiosis. A combination of 2-dimensional electrophoresis, immunoblotting, and mass spectrometric analysis were used to identify novel antigens from the sporozoites of Eimeria stiedae. Protein spots were recognized by the sera of New Zealand rabbits infected artificially with E. stiedae. The proteins were characterized by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF/TOF-MS) analysis in combination with bioinformatics. Approximately 868 protein spots were detected by silver-staining, and a total of 41 immunoreactive protein spots were recognized by anti-E. stiedae sera. Finally, 23 protein spots were successfully identified. The proteins such as heat shock protein 70 and aspartyl protease may have potential as immunodiagnostic or vaccine antigens. The immunoreactive proteins were found to possess a wide range of biological functions. This study is the first to report the proteins recognized by sera of infected rabbits with E. stiedae, which might be helpful in identifying potential targets for vaccine development to control rabbit coccidiosis.

High pathogenicity and strong immunogenicity of a Chinese isolate of Eimeria magna Pérard, 1925

Coccidia infection of rabbits with one or several species of parasites of the genus Eimeria causes coccidiosis, a disease leading to huge economic losses in the rabbit industry. Eimeria magna, one of the causal agents of rabbit coccidiosis, was characterized as mildly pathogenic and moderately immunogenic in previous studies. In this study, we identified a Chinese isolate of E. magna by testing its biological features (oocyst morphology and size, prepatent time) and sequencing its internal transcribed spacer 1 (ITS-1) DNA fragment. This isolate is highly pathogenic; infection of rabbits with only 1×102 oocysts caused a 55% reduction in weight gain in 14days. In addition, immunization with 1×102 oocysts prevented body weight loss against re-infection with 5×104 oocysts, indicating the high immunogenicity of this isolate. Our study described the distinctive phenotype of the Chinese isolate of E. magna and contributed to the research of geographic variation of rabbit coccidia.

Transgenic Eimeria magna Pérard, 1925 Displays Similar Parasitological Properties to the Wild-type Strain and Induces an Exogenous Protein-Specific Immune Response in Rabbits (Oryctolagus cuniculus L.).

Rabbit coccidiosis causes great economic losses to world rabbitries. Little work has been done considering genetic manipulation on the etiological agents, rabbit Eimeria spp. In this study, we constructed a transgenic line of Eimeria magna (EmagER) expressing enhanced yellow fluorescent protein (EYFP) and red fluorescent protein (RFP) using regulatory sequences of Eimeria tenella and Toxoplasma gondii. We observed the life cycle of EmagER and confirmed that the transgenic parasites express exogenous proteins targeted to different cellular compartments throughout the entire life cycle. EYFP was expressed mainly in the nucleus and RFP both in the nucleus and cytoplasm. Then, coccidia-free, laboratory-reared 40-day-old rabbits were primarily infected with either EmagER or wild-type strain oocysts and challenged with the wild-type strain. EmagER showed similar reproductivity and immunogenicity to the wild-type strain. Finally, we examined the foreign protein-specific immune response elicited by EmagER. Rabbits were immunized with either transgenic or wild-type oocysts. Immune response against parasite-soluble antigen, EYFP and RFP in spleen, and mesenteric lymph nodes were detected by quantitative real-time PCR. The relative expression level of IFN-γ, IL-2, and TNF-α were higher in EmagER-immunized rabbits than wild-type parasites-immunized rabbits after stimulation with EYFP and RFP. Our study confirmed that a specific immune response was induced by the exogenous protein expressed by EmagER and favored future studies on application of transgenic rabbit coccidia as recombinant vaccine vectors.

Stable Transfection of Eimeria intestinalis and Investigation of Its Life Cycle, Reproduction and Immunogenicity.

Rabbit coccidiosis, caused by infection of Eimeria spp. is one of the most severe parasitic diseases in rabbits. Eimeria intestinalis is one of the most immunogenic species in rabbit coccidia. Due to the lack of genomic information and unsuccessful in vitro cultivation, genetic manipulation of rabbit coccidia lagged behind other apicomplexan parasites. Using regulatory sequences from E. tenella, we obtained a transgenic line of E. intestinalis expressing yellow fluorescent protein (YFP). YFP was continuously expressed throughout the whole life cycle. Morphological features of E. intestinalis in different developmental stages were dynamically observed with the transgenic line. Some important features in the endogenous development stages were observed. Trophozoites were found as early as 4 h post inoculation. Two types of schizonts and merozoites were observed in first three of the four schizogonies. Beside jejunum and ileum, gametogony stage and oocysts were also found in the duodenum and vermiform appendix. In addition, the transgenic strain was highly immunogenic but less pathogenic than the wild type. Considering the high immunogenicity of E. intestinalis and amenability to transfection with foreign genes, transgenic E. intestinalis could be a promising oral eukaryotic vaccine vector.

Pathological and ultrastructural observations and liver function analysis of Eimeria stiedai-infected rabbits

To study the pathogenicity of Eimeria stiedai, sporulated oocysts were given orally to coccidian-free two-month-old New Zealand rabbits(1000±20g). After 30days, blood samples from the rabbit hearts were collected for routine blood tests, liver functions and four characteristics of blood coagulation. Additionally, specimens of the liver, bile duct and duodenum were collected to observe the changes in pathology and ultrastructure. E. stiedai severely restricted the growth and development of rabbits. Blood tests showed that glutamine transferase (GGT) and serum cholinesterase (ChE) were significantly different from the non-infected controls. Other extremely significant differences were observed in the biochemical indices of routine blood tests, liver function and four blood coagulation characteristics, indicating that the liver functions were significantly affected. Staining showed that, compared with the negative control group, the liver, bile duct and duodenum contained significant numbers of lesions, and organs and cell structures suffered severe damage in ultrastructure, which greatly affecting bodily functions. E. stiedai-infected rabbits model was successfully established, which might provide a theoretical basis for research on the pathogenesis of rabbit coccidia, and the diagnosis and prevention of coccidiosis in rabbits.

Molecular detection of Eimeria stiedae in an Angora rabbit

Hepatic coccidiosis caused by Eimeria stiedae, results in severe infection, outbreaks and deaths in young rabbits. Disease is diagnosed by time consuming methods like fecal examination, oocyst sporulation and necropsy. The aim of this study was to detect E.stiedae with species specific Polymerase Chain Reaction (PCR), without waiting oocyst sporulation and necropsy. Impression smears were prepared from liver nodules and stained with giemsa. Fecal samples were collected from the intestines and examined by centrifugal flotation with salt solution to detect Eimeria spp. oocysts. Then oocysts were sporulated in 2.5% (w/v) aqueous potassium dichromate (K2Cr207). Primers specific to E.stiedae were used in PCR reaction. Eimeria spp. oocysts were detected after the examination of impression smears and bowel content. E.stiedae was diagnosed after the measurement of sporulated oocyst and PCR. At the end of the study, we think that; PCR will be very valuable for the rapid and true diagnosis of hepatic coccidiosis in rabbits.

The complete mitochondrial genomes of five Eimeria species infecting domestic rabbits

Rabbit coccidiosis caused by members of the genus Eimeria can cause enormous economic impact worldwide, but the genetics, epidemiology and biology of these parasites remain poorly understood. In the present study, we sequenced and annotated the complete mitochondrial (mt) genomes of five Eimeria species that commonly infect the domestic rabbits. The complete mt genomes of Eimeria intestinalis, Eimeria flavescens, Eimeria media, Eimeria vejdovskyi and Eimeria irresidua were 6261bp, 6258bp, 6168bp, 6254bp, 6259bp in length, respectively. All of the mt genomes consist of 3 genes for proteins (cytb, cox1, and cox3), 14 gene fragments for the large subunit (LSU) rRNA and 11 gene fragments for the small subunit (SSU) rRNA, but no transfer RNA (tRNA) genes. The gene order of the mt genomes is similar to that of Plasmodium, but distinct from Haemosporida and Theileria. Phylogenetic analyses based on full nucleotide sequences using Bayesian analysis revealed that the monophyly of the Eimeria of rabbits was strongly statistically supported with a Bayesian posterior probabilities. These data provide novel mtDNA markers for studying the population genetics and molecular epidemiology of the Eimeria species, and should have implications for the molecular diagnosis, prevention and control of coccidiosis in rabbits.

Coccidiosis in rabbits in a subtropical hilly region

A detailed study on rabbit coccidiosis in a subtropical hilly region of India regarding prevalence, intensity of infections, species involved and control measures adopted during mortality in a rabbit farm due to coccidiosis, was undertaken for awareness of the rabbit owners of the hilly region. Overall 57.28% rabbits were found positive for coccidial infections. Mortality in rabbit was diagnosed due to coccidiosis. Six species of Eimeria were identified i.e. E. magna, E. exigua, E. piriformis, E. coecicola, E. intestinalis and E. media and thus intestinal coccidiosis were found responsible for such mortality. Treatment with oral administration of amprolium soluble powder 20% w/w @1g/litre of drinking water for 10 days was found to be effective to control the mortality while individual treatment was found effective to control mortality rather than group treatments. A correlation between occurrences of coccidiosis with meteorological parameters was also established. It has been concluded from this study that pathogenesity of species of Eimeria and effectiveness of medicine are region specific. Only intestinal coccidiosis could able to causes mortality in rabbit without involvement of the hepatic coccidiosis. The rainy season particularly the month of August was very much susceptible for coccidian infection in subtropical hilly region.

Prevalence, pathology and risk factors for coccidiosis in domestic rabbits (Oryctolagus cuniculus) in selected regions in Kenya

Background: The potential for rabbit production in Kenya is high. However, high morbidity and mortality of domestic rabbits were reported.Objective: The aim of the study was to determine the pathology, prevalence and the predisposing factors to coccidiosis in domestic rabbits in selected regions in Kenya.Animals and methods: A total of 61 farms keeping rabbits in six different counties were visited in the survey. A total of 2680 live rabbits were examined and 61 rabbits and 302 fecal samples were randomly collected from the farms and examined for coccidian oocysts by ante-mortem and post-mortem methods. The predisposing factors to coccidiosis were assessed through questionnaires and direct observation. Chi square (χ2) statistics was used with P values < 0.05 considered statistically significant.Results: Of the 302 fecal samples, 85% (P < 0.001) contained coccidian oocysts and 2% harbored nematode eggs (Passalurus ambiguous). The overall prevalence of Eimeria spp. infestation was 85.1% in the study area and 90.2% in the individual rabbits, while prevalence of intestinal coccidiosis and hepatic coccidiosis was 29.5% and 11.5%, respectively. Higher counts of coccidian oocysts per gram of feces were recovered in weaners than in growers and adults rabbits (P < 0.001), rabbits that were kept in high density group housing (P < 0.05) and housing with more than two tiers.Conclusion: This study identified group housing of rabbits of different ages and inadequate control of concurrent infections as the major risk factors associated with coccidiosis in domestic rabbits in Kenya.

The complete mitochondrial genome sequence of Eimeria magna (Apicomplexa: Coccidia)

In the present study, we determined the complete mitochondrial DNA (mtDNA) sequence of Eimeria magna from rabbits for the first time, and compared its gene contents and genome organizations with that of seven Eimeria spp. from domestic chickens. The size of the complete mt genome sequence of E. magna is 6249 bp, which consists of 3 protein-coding genes (cytb, cox1 and cox3), 12 gene fragments for the large subunit (LSU) rRNA, and 7 gene fragments for the small subunit (SSU) rRNA, without transfer RNA genes, in accordance with that of Eimeria spp. from chickens. The putative direction of translation for three genes (cytb, cox1 and cox3) was the same as those of Eimeria species from domestic chickens. The content of A + T is 65.16% for E. magna mt genome (29.73% A, 35.43% T, 17.09 G and 17.75% C). The E. magna mt genome sequence provides novel mtDNA markers for studying the molecular epidemiology and population genetics of Eimeria spp. and has implications for the molecular diagnosis and control of rabbit coccidiosis.

Induced metabolic disturbance and growth depression in rabbits infected with Eimeria coecicola

Eimeria coecicola causes intestinal coccidiosis in rabbits and, thereby, enormous economic losses in rabbit farms. This study aimed to investigate the effect of intestinal coccidial infection, E. coecicola on metabolic status and growth of rabbits. Animals were allocated into two groups with eight rabbits each; one group was orally inoculated with saline and served as control while the other group was orally inoculated with 5 × 10(4) sporulated oocysts. On day 7 postinfection, fecal expulsion of E. coecicola oocysts is maximal (1.2 × 10(6) oocyst/g feces) and rabbits have lost approximately 23% of their weight. Infection induced a severe depletion in plasma growth hormone level. In addition, the energy metabolic status was significantly (P ≤ 0.05) altered by the infection as, both blood glucose and total lipid levels were significantly elevated with mutual depletion in carbohydrate stores in liver sections. Also, the thyroid-stimulating hormone and cortisol concentrations were raised as a consequence of the infection. Moreover, protein status was affected by the infection as both liver and plasma total proteins were significantly decreased with concurrent disturbance in the blood protein electrophoretic pattern and duplication of blood urea nitrogen concentration. Finally, the infection induced plasma electrolyte imbalance as indicated by a significant decrease in sodium, potassium, calcium, phosphorus, ferrous, and selenium ions. Our data suggested that the intestinal coccidial infection of rabbits with E. coecicola has serious effects on rabbit growth and metabolism and could disrupt endocrine and electrolyte homeostasis.

Eimeria coecicola: Spleen response of Oryctolagus cuniculus

The apicomplexan protozoon Eimeria coecicola is an infectious agent of intestinal coccidiosis in rabbits, causing severe injuries in the appendix as the final target, but also in the liver though not being a target. Here, we investigated the effect of E. coecicola on the spleen of the rabbit Oryctolagus cuniculus with respect to structure and gene expression using 2-color Agilent whole rabbit genome oligo-microarray technology in combination with quantitative PCR. At maximal fecal output of E. coecicola oocyts on day 7p.i., the spleen did not contain any parasites, but displayed moderate inflammatory changes evidenced as fused white pulp areas, diffuse appearance of the marginal zones, and increased number of macrophages in the red pulp, eventually resulting in an increased histological score. The infections induced 36 genes to be up-regulated and 156 genes to be down-regulated, among which were 139 genes encoding diverse regions of antibodies. The highest upregulated genes were those encoding granzyme H (10-fold), lim1 (10-fold), xanthine dehydrogenase (9-fold), whereas the downregulated genes could be majorly assigned to the immune response, as e.g. the genes encoding the macrophage cationic peptide-2 (5-fold). Quantitative PCR of genes encoding GZMH, XDH, HSD17B1, SULT3A1, SAA, BPI, MCP-2, and GST exhibited the same transcriptional level as that detected by microarray analysis. The E. coecicola-induced changes in gene expression of the spleen were totally different to those found previously in appendix and liver. Only the granzyme H gene became upregulated in all three organs. Our data indicate that the spleen, though not a final target of E. coecicola, responds to E. coecicola infections, suggesting that the spleen may be part of an orchestrated host defense against E. coecicola critically involving GZMH-expressing NK-cells.

Trace elements changes in the appendix of rabbit infected with Eimeria coecicola

The parasitic protozoa, Eimeria coecicola, causes intestinal coccidiosis in rabbits and, thereby, enormous economic losses in rabbit farms. This study aimed to investigate the trace elements changes in the appendix of infected rabbits with E. coecicola. Rabbits were orally infected with 50000 sporulated oocysts of E. coecicola, began to shed parasitic oocysts with their faeces on day 5 post-insemination (p.i.) and approximately 1.1 million oocysts were maximally shedded on day 7 p.i. At maximal shedding, animals were euthanized and appendiceal samples were collected. The coccidial infection was accompanied with a decrease in weight of infected rabbits reaching 25% at day 7 p.i. Our results showed that the concentration of iron, boron, cadmium, cobalt, manganese and zinc was significantly increased due to E. coecicola infection. On the contrary, the concentration of sodium, potassium and calcium was not significantly changed. Also the number of goblet cells in the appendiceal villi was significantly decreased. It was shown that E. coecicola infection has induced an alteration in the level of some trace elements as well as goblet cells. Key words: Trace elements, Eimeria coecicola, rabbits.

Prevalence of Coccidiosis in Domestic Rabbits (Oryctolagus cuniculus) in Northwest China

Prevalence of Coccidiosis in Domestic Rabbits (Oryctolagus cuniculus) in Northwest China

Gene expression in rabbit appendices infected with Eimeria coecicola

Eimeria coecicola causes intestinal coccidiosis in rabbits and, thereby, enormous economic losses in rabbit farms. Here, we investigate the final target site of E. coecicola, the appendix of rabbits, at the level of gene expression. Rabbits, orally infected with E. coecicola, begin to shed parasitic oocysts with their feces on day 5 p.i., and approximately 1.1 million oocysts are maximally shedded on day 7 p.i. At maximal shedding, the appendix has increased in size by about 2–3-folds and reveals increased hemorrhage which is associated with increases in nitrite/nitrate, malondialdehyde and catalase activity and a decrease in glutathione. Agilent 2-color oligo whole rabbit genome microarray, in combination with quantitative real-time PCR, detects 45 and 36 genes whose expression is more than 2-fold up- and down-regulated, respectively, by E. coecicola infection on day 7 p.i. The most dramatic increase by approximately 50-fold reveals the mRNA of the pro- and anti-inflammatory pleiotropic cytokine interleukin 6 (IL-6), whereas the largest decrease by approximately 13-fold is detected for mRNAs encoding for DBP, SULT3A1, CRP and glutathione-S transferase. Also, there are up- and down-regulations in the expression of genes encoding diverse regions of antibodies. Our data suggest that IL-6 plays a central role in the infection of the appendix of rabbits by E. coecicola, presumably involved in both pathological injuries, host defences and healing processes.

Pathological changes and local defense reaction occurring in spontaneous hepatic coccidiosis in rabbits (Oryctolagus cuniculus).

Hepatic coccidiosis occurred in 56 rabbits belonging to different ages, sexes and breeds during the years from 2002 to 2005. Clinically, the severely affected rabbits showed decreased growth rate, anorexia, debilitation, listlessness, diarrhea, icterus and rough hair coat. Postmortem examinations revealed increased dirty dull straw colored peritoneal fluid. Hepatomegaly, with presence of discrete yellowish-white nodules of 1mm to 1 cm size on the surface and throughout the parenchyma, was seen. Smears from peritoneal fluid showed rafts of mesothelial cells. Impression smears from the liver nodules revealed presence of numerous developmental stages of Eimeria stiedae corresponding with the stage of the liver lesion. These were intermixed with sheats of hepatobiliary cells and inflammatory cells and the changes were reflective of the histological changes like biliary hyperplasia, cholangitis and vacuolar changes occurring in the liver. There was increase in the thickness of basement membrane with the advanced stage of the lesion. The basement membrane was up to 1-2 µm in thickness forming loop like structures over which resided hyperplastic biliary cells containing different stages of the parasite. Some thickened basement membranes were devoid of overlying cells which had desquamated and were present in the ductal lumens suggesting that the basement might have the local defensive role in warding of the coccidial infection. The basement membrane was positive for neutral mucopolysaccharides while as the inflammatory zones and biliary epithelia along with the gametogonic stages of the coccidium reacted positively to the increased acid mucopolysaccharides qualitatively. The results showed that the occurrence of hepatic coccidiosis in female rabbits coincided with the breeding and kindling periods. Direct wet mount smears from bile aid in diagnosis of the disease. Impression smears from the liver nodules might represent the histological changes in the liver. The basement membrane thickening might have a defensive role in warding off the coccidial infection.

RABBIT COCCIDIOSIS AND ITS CONTROL : A REVIEW

Coccidiosis caused by Eimeria species, is a major parasitic disease of rabbits and is responsible for a high incidence of morbidity and mortalitv. The incidence of this disease in European countries in 21-60% and in India 13-64%. In commercially reared rabbits; coccidiosis occurs .in a subclinical form with growth retardation and altered feed conversion. The disease occurs in two forms, hepatic and intestinal, the latter being more common than the former. Presently, the control of rabbit coccidiosis relies almost entirely on chemical coccidiostats. However, extensive use of such drugs in commercial rabbitries has already started creating problems of drug resistance. In view of the limitations of chemotherapy, it is imperative to develop immunoprophylactic measures against rabbit coccidiosis. These include development of live-attenuated and recombinant vaccines against the parasite.