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Pathology and treatment of Eimeria zuernii coccidiosis in calves: investigations in an infection model.

Two studies were conducted in the Eimeria zuernii infection model in order to investigate the pathology of E. zuernii coccidiosis and the efficacy of toltrazuril (Baycox 5% suspension) in this infection. For this purpose, a total of 30 calves were infected experimentally with E. zuernii oocysts and faecal samples taken regularly from the rectum and examined for faecal consistency and oocyst excretion. Six of the calves underwent pathological examination at various points in time after infection. Significant macroscopic and microscopic changes were demonstrated and parasitic stages were identified in the intestinal mucosa of infected calves during the late prepatent and patent period. Inflammatory reactions revealed by light microscopy were confirmed by electron microscopical investigations. Treatment of calves with toltrazuril during the late prepatent period resulted in significantly lower frequencies of diarrhoea and levels of oocyst excretion, and weight gain was significantly higher than in shamtreated animals.

Animals↗

Dietary modulation of avian coccidiosis.

During the past several years, our laboratory has been investigating the anticoccidial activities of various natural products that have potential use as dietary supplements for coccidiosis control. Sources of fats containing high concentrations of n-3 fatty acids such as menhaden oil and flaxseed oil and flaxseed, when added to starter rations and fed to chicks from one day of age, effectively reduce lesions caused by the caecal parasite Eimeria tenella, but not lesions caused by Eimeria maxima. Our results are consistent with reports of effects of diets high in n-3 fatty acids on other protozoan parasites which suggest that the state of oxidative stress induced by these diets in the cells of both host and parasites is responsible for their parasitic actions. Artemisinin, a naturally occurring (Artemisia annua) endoperoxide and effective antimalarial significantly lowers lesions from E. tenella when given at low levels as a feed additive. The mechanism of its action is also considered to involve induction of oxidative stress. Diets supplemented with 8 p.p.m. gamma-tocopherol (abundant in flaxseeds) or with 1% of the spice tumeric, reduce mid-small intestinal lesion scores and improve weight gains during E. maxima infections. These compounds may exert their anticoccidial activity because they are effective antioxidants. Betaine, a choline analogue found in high concentrations in sugar beets, improves nutrient utilisation by animals under stress. When provided as a dietary supplement at a level of 0.15% it has enhanced the anticoccidial activity of the ionophore, salinomycin. Betaine may act as an osmoprotectant whereby it improves the integrity and function of the infected intestinal mucosa. In in vivo studies, betaine plus salinomycin significantly inhibit invasion of both E. tenella and E. acervulina. However, subsequent development of E. acervulina is inhibited more effectively with this combination treatment than development of E. tenella.

Animals↗

Vaccination against Eimeria magna coccidiosis using spray dispersion of precocious line oocysts in the nest box.

Coccidiosis mostly affects young rabbits just after weaning (5- to 6-week-old animals). Prevention of this disease must therefore be initiated before weaning. 'Precocious lines', derived from field species display good immunogenicity, though not pathogenic when administered at the right dose. In the present work, we tested the vaccination method of the whole litter at 25 days of age by spray dispersion of oocysts of a precocious line of Eimeria magna in the nest box. Three doses were tested, d1 = 4 x 10(2) oocysts, d2 = 4 x 10(3) oocysts, d3 = 4 x 10(4) oocysts. The animals were challenged individually with 10(4) oocysts of a wild strain of E. magna at 35 days of age, 5 days after weaning. The oocyst output and weight gain were recorded after vaccination and after challenge. The vaccinated animals did not display any vaccine reaction. The dose d3 was totally effective on oocyst output and on weight gain under our experimental conditions. As our challenge conditions were severe, we think that a lower vaccine dose could be used. This method proved to be efficient, and quick and easy to use because it did not require animal manipulation.

Animals↗

Coccidiosis in goats in the Czech Republic.

An observational study was conducted to determine coccidial infections in goats of 13 farms in the Czech Republic. The prevalence of oocysts of Eimeria species in kids (less than 3 months old), weaned but not served goats (from 3 months to 1 year), and adult goats (1 year or more) was determined. Nine Eimeria species were identified in fecal samples by Sheather's sugar flotation technique. The overall prevalence of Eimeria oocysts in fecal specimens was 92.2%. Eimeria arloingi was the most common species with an overall prevalence of 84%, followed by E. hirci (63%) and E. ninakohlyakimovae (56%). Other species present were E. christenseni (55%), E. alijevi (36%), E. caprina (25%), E. aspheronica (12%), E. capriovina (6%) and E. jolchijevi (2%). Two or more Eimeria species were detected in 88% of the samples. The most prevalent species in kids was E. arloingi, while in weaned but not served and adult goats E. ninakohlyakimovae was the most frequently found. The number of oocysts excreted was generally lower in adult goats (2567.3+/-12678 OPG), whereas higher number oocyst per gram of feces (OPG) were found in kids (18565+/-24888 OPG). Clinical coccidiosis was detected in two farms, and E. arloingi and E. ninakohlyakimovae were implicated as its cause. Disease was observed in kids 2 to 4 weeks after weaning and watery feces with clumps of mucus, and color changes from brown to yellow or dark tarry, weight loss, and dehydration were the most conspicuous clinical signs. At necropsy, macroscopic changes included mucosal hemorrhages and whitish nodular polyps in the jejunum were found. Histopathological changes were characterized by local hypertrophy and hyperplasia of intestinal villi, villus blunting and inflammatory infiltration in the lamina propria. Numerous developmental stages of the parasites were observed in enterocytes and lacteals of intestinal villi.

Age Factors↗

Prevention of Eimeria alabamensis coccidiosis by a long-acting baquiloprim/sulphadimidine bolus.

Twelve calves aged 6-10 months, and 12 calves aged 10-16 months were turned out onto a permanent pasture known to have been contaminated with oocysts of Eimeria alabamensis during the previous year. Two days after turnout, six of the older calves and six of the younger were each treated with one bolus per 200 kg bodyweight containing 1.6 g baquiloprim and 14.4 g sulphadimidine. The other 12 calves were left untreated. The excretion of Eimeria oocysts, the faecal dry matter and the weight gain of treated and untreated calves within each age group were compared during the first 3 weeks on pasture to assess the efficacy of the bolus in preventing E. alabamensis coccidiosis. All the older of the untreated calves and four of the younger developed gruel-like to watery diarrhoea 4-7 days after turnout. The faecal consistency of the treated calves remained firm and they lost significantly less weight than the control calves during the first 13 days on pasture. The treated calves also excreted significantly fewer oocysts during the first 20 days of grazing; their oocyst excretion remained low during days 8-10 when all but one of the diarrhoeic control calves excreted more than 850,000 oocysts per gram faeces (OPG). Starting on days 12 to 14 the oocyst excretion of 8 of the treated calves increased to 20,000-65,000 OPG and of 2 calves to 210,000-240,000 OPG. There was no difference in oocyst output between treated and untreated calves from the fourth week of grazing and no difference in weight gain among the younger calves. In the older calves there was a tendency for the untreated calves to gain more weight than treated calves.

Animal Feed↗

Administration of toltrazuril during experimental coccidiosis in mule ducks: comparison of the efficacy of a single administration at two different endogenous stages.

An experimental Eimeria mulardi coccidiosis was reproduced in mule ducks. A single dose of toltrazuril (7 mg per kg) was administered at two different endogenous stages: Day 2 (first meronts) or Day 5 (last meronts and gamonts). The efficacy of the drug was assessed on four criteria (body weight, oocyst counts, macroscopic lesions, and presence of the meronts and gamonts). To have a curative effect, a single dose of toltrazuril should be administered early on. However, a single treatment on Day 5 had a prophylactic effect.

Animals↗

Studies on coccidiosis in goats in Poland.

The study was carried out in a flock consisting of 110 goats. Nine species of coccidia were found: Eimeria christenseni, E. arloingi, E. jolchijev, E. ninakohlyakimovae, E. alijevi, E. apsheronica, E. caprina, E. caprovina and E. hirci. Eighty-one percent of adults and 100% of kids were infected. Number of oocysts per gram of feces in kids ranged form 1200 to 202000. Clinical symptoms in about 50% of kids were observed. Toltrazuril (Baycox, Bayer), 20 mg/kg of body weight was highly efficacious in therapy of goat coccidiosis.

Animals↗

Coccidiosis in swine.

It is clear that although the clinical history, pathologic lesions, and endogenous stage life cycle of I. suis are well understood, the epidemiology of this parasite is not understood or is misunderstood. Consequently, treatment of individual piglets and prophylactic use of coccidiostats in sows have not been consistently rewarding. The best control at present is achieved through use of extensive sanitation, particularly steam cleaning. The incidence of clinical coccidiosis in piglets continues to be a major component (approximately 20 per cent) in the differential etiology of scours in baby pigs.

Animals↗

Coccidiosis in the European badger, Meles meles in Wytham Woods: infection and consequences for growth and survival.

In total 1502 faecal samples were collected from a population of European badgers (Meles meles) between 1992 and 1995 at Wytham Woods, Oxfordshire, UK. Two coccidia species, Eimeria melis and Isospora melis, were identified. Cubs showed a marked seasonal pattern of infection with E. melis, with infection occurring at significantly higher intensity and prevalence than in adults. There was preliminary evidence to suggest that infantile coccidiosis in badgers may be associated with impaired growth and increased mortality.

Age Factors↗

Coccidiosis of the wild rabbit (Oryctolagus cuniculus) in France.

In 1998-1999 a survey of coccidiosis in wild rabbits was carried out in six different localities in France. About five individuals were caught monthly in each locality and a total of 254 wild rabbits was examined. Ten species of Coccidio were identified: Eimeria perforans, E. flavescens, E. piriformis, E. exigua, E. media, E. magna, E. coecicola, E. stiedai, E. roobroucki, E. intestinalis. Intensity of infection in young individuals was higher than in adults. Intensity was highest in winter but, as there are no young rabbits in winter, in young individuals it was higher in spring and autumn than in summer. Intensities were higher in the northern rather than in southern localities. Ranking of prevalence was remarkably stable, in contrast to the variability of the parasitic load. The equilibrium between congeneric species of rabbit coccidia (stable prevalence rank, variable parasitic load) is thought to be probably the consequence of the opportunistic feeding habits of rabbits.

Age Factors↗

Infection by Salmonella typhimurium, S. agona, S. enteritidis or S. infantis of chicks with caecal coccidiosis.

Experimental infections of Salmonella typhimurium, S. agona, S. enteritidis or S. infantis were studied in chicks infected with Eimeria tenella. In all experiments, 4-d old birds were given 5 daily oral doses of approximately 10(4) salmonella organisms per bird. One day before this inoculation one group of birds received a single dose, in the range 1 X 10(4) to 4 X 10(4) sporulated oocysts of E. tenella per os whilst the other group was not inoculated and served as the control. Chicks were examined post morten 7, 10 or 14 d after receiving coccidia. With S. typhimurium infection, the number of salmonellas in the caeca of the E. tenella-infected birds was greater than in those infected only with salmonella. With S. agona and S. enteritidis, the counts of salmonella in the caeca and the numbers of birds positive for salmonella in the caeca and liver were greater in the E. tenella-infected birds. The rate of infection of S. infantis was not increased by caecal coccidiosis.

Animals↗

Genetics of resistance to coccidiosis: response of inbred chicken lines to infection by Eimeria tenella and Eimeria maxima.

1. Experiments have been carried out to compare weight gain, mortality and oocyst production in 7 inbred and partially inbred lines of chickens after challenge with the coccidial parasites Eimeria tenella and E. maxima. 2. There were large differences between lines in the effects of challenge on weight gain and mortality for both species of parasite. However, the lines suffering the greatest mortality were not those showing the greatest effects on weight gain, indicating that mortality alone is not an adequate criterion in selection for resistance. 3. Although oocyst production differed between lines there was no correlation with mortality or with weight loss, implying that the variation observed in these traits was not due to a restriction of the parasite but to an accommodation of its effects. 4. Mortality and weight loss resulting from challenge with E. tenella in the different lines did not correlate with that caused by E. maxima. 5. There was evidence of an association of genes of the major histocompatibility complex genes with mortality, but not with weight loss or oocyst production: there was no indication of association of resistance to coccidiosis with resistance to Marek's disease.

Animals↗

Baby pig diarrhea caused by coccidiosis.

An outbreak of coccidiosis on two Belgian farms is described. Diarrhea started in piglets at 9 or 10 days of life. Zero to three pigs died per litter. The morbidity rate varied from 70 to 90 per cent. Histological examination of the intestines revealed shortening of villi and different stages of the life cycle of coccidia were seen in the enterocytes. Virological examination was negative for corona-, corona-like, and rotavirus. A haemolytic E. coli strain was isolated in one case. As for treatment, good results were obtained by the adding of 1 kg amproleum pre-mix per ton sow feed. Scouring pigs were treated orally with 2 cc of an amprol solution once a day. The diarrhea stopped one day after treatment.

Animals↗

Pathology and pathogenesis of disseminated visceral coccidiosis in cranes.

Disseminated visceral coccidiosis (DVC) caused by Eimeria spp. was recognized as a disease entity in captive sandhill cranes (Grus canadensis) and whooping cranes (Grus americana) in the late 1970s. While most avian species of Eimeria inhabit the intestinal tract of its host, the crane eimerians, Eimeria reichenowi and Eimeria gruis, invade and multiply systemically and complete their development in both digestive and respiratory tracts. In DVC, cranes, especially chicks, may succumb to acute infections resulting in hepatitis, bronchopneumonia, myocarditis, splenitis, and enteritis. Cranes may also develop chronic, subclinical infections characterized by granulomatous nodules in various organs and tissues. This paper reviews the pathology and pathogenicity of natural and experimental DVC in sandhill and whooping cranes. Naturally infected birds appeared clinically normal, but progressive weakness, emaciation, greenish diarrhea, and recumbency before death were observed in birds administered doses > or = 10 x 10(3) sporulated oocysts per os. At necropsy, naturally infected birds had nodules in the mucosa of the oral cavity and the esophagus, and in thoracic and abdominal viscera. Experimentally infected birds necropsied less than 7 days after infection (a.i.) had no gross lesions. Birds examined later had hepatosplenomegaly, liver mottling, lung congestion and consolidation with frothy fluid in airways, and turgid intestinal tracts with hyperemic mucosa. From 28 days a.i., grossly visible granulomatous nodules were seen in the esophagus, heart, liver, cloaca, and eyelids. By light microscopy, the basic host response was a granulomatous inflammation with non-suppurative vasculitis affecting many organs and tissues. With time, multifocal aggregates of mononuclear cells, many laden with asexual coccidial stages, increased in size and number. Widespread merogony resulted in morbidity and death, particularly in birds administered 20 x 10(3) sporulated oocysts. Ultrastructural examination revealed developing asexual coccidian stages in the cytoplasm of large lymphocytes or monocytes within a parasitophorous vacuole, often indenting the nucleus. Oocysts and gametocytes were found in the intestines by 12 days a.i., and in the esophagus, trachea, bronchi, and lung by 14 days a.i., indicating that crane eimerians can complete their life cycle at these sites. Thus, DVC in cranes could be a useful animal model for the study of eimerian extra-intestinal stages and the evaluation of potential systemic anticoccidial drugs.

Animals↗

Gordon memorial lecture. Coccidiosis control: past, present and future.

Hygiene, management, chemotherapy and immunity all play a part in the control of coccidiosis. Under the conditions of modern intensive poultry rearing, special reliance is placed upon chemotherapy and since the introduction of the sulphonamides in 1939 a sequence of different types of drugs has been developed. At present the field is dominated by the ionophore antibiotics which have a special mode of action against the extracellular phases of the parasitic life cycle. Drug resistance is a continuing problem which has limited the effective life of most types of drug, although it has been most significant for particular compounds. So far it has not severely affected the efficacy of the ionophores. Immunity is involved in effective prophylaxis and the strong protective immunity which is a feature of most coccidial infections offers promise of a vaccination system. However, much more research will be necessary to bring this promise to fruition. Studies on immune mechanisms, antigenicity, biochemistry and in vitro cultivation may all contribute to the development of methods for controlling a series of infections which are an important obstacle to the development of modern husbandry methods.

Animals↗

Immunogenic characterization of a tissue culture-derived vaccine that affords partial protection against avian coccidiosis.

The immunogenicity of a tissue culture-derived vaccine generated from an Eimeria tenella-infected cell line in a serologically defined bird line, and the ability to confer protection against homologous challenge in young chicks was examined. The cell line, SB-CEV-1/F7, was infected with E. tenella sporozoites and the resulting 72-h postinfection cell-free supernatants were adjuvanted and used to immunize Leghorn chicks homozygous for the B19 haplotype. Peripheral blood and splenic lymphocytes from these immunized birds proliferated in vitro in response to both sporozoite and SB-CEV-1/F7 tissue culture-derived parasite antigens. In addition, splenic immune lymphocytes obtained from birds previously exposed to E. tenella in vivo responded to these tissue culture-derived parasite antigens in vitro. To evaluate the efficacy of the vaccine, B19B19 chicks were vaccinated s.c. with adjuvanted 72-h postinfection cell-free supernatants or an ammonium sulfate precipitate derivative thereof, orally boosted, and then subjected to homologous parasite challenge at 10 d of age. The level of protection (body weight gain, cecal lesions) was assessed 6 d after challenge. Performance results from four battery trials demonstrated that vaccinated birds were significantly protected against weight loss compared to unimmunized, challenged controls. In addition, in two of the four trials, vaccinated birds were significantly protected against lesions. These results provide strong evidence that tissue culture-derived parasite antigens obtained from the E. tenella-infected SB-CEV-1/F7 cell line are immunogenic in birds and can provide partial protection against E. tenella clinical coccidiosis.

Aging↗

Assessment of recombinant bovine somatotropin as an immunomodulator during avian coccidiosis: immunization with living oocysts.

Coccidiosis, a disease of great economic importance to the poultry industry, is generally controlled prophylactically by additions of anticoccidial drugs to the feed. However, increasing development of drug-resistant coccidia species has stimulated searches for alternative control methods, one of which is vaccination. As part of this effort, recombinant bovine growth hormone (rbST) was tested as a possible immune stimulator in combination with live oocyst vaccination. At a dose of 0.045 mg per chick, given by s.c. injection at 1 d of age, rbST did not improve immunity developed by immunization with 500 or 2,500 oocysts of Eimeria maxima as judged by weight gain and lesion scores. At a single dose of 0.09 mg per chick given at 1 d of age in combination with IMMUCOX, rbST provided some protection against challenge infection with Eimeria tenella but not Eimeria acervulina as judged by reduction in lesion scores. Treatment with 0.09 mg rbST per chick alone at 1 and 3 d of age was protective against challenge with E. tenella but not E. acervulina or E. maxima as judged by reduction in lesion scores. These results strongly indicate that rbST can act as an immune modulator in chickens infected with coccidia, and provide a basis for further investigations of its use as a vaccine adjuvant.

Adjuvants, Immunologic↗

Mapping quantitative trait loci associated with resistance to coccidiosis and growth.

To map QTL associated with disease resistance to avian coccidiosis and growth, two commercial broiler lines with different degrees of resistance to the disease were crossed to generate an F1 generation that was intercrossed to produce 314 F2 generation offspring. The F2 offspring were inoculated with sporulated oocysts of Eimeria maxima. Five disease-associated phenotypes were measured after the infection. Intertrait comparisons revealed that oocyst shedding was a good parameter for evaluating disease resistance or susceptibility. One hundred nineteen microsatellite markers, covering 80% of the chicken genome with an average marker interval of 25 cM, were used for genotyping of F1 parents and F2 offspring. Statistical analysis based on the data of four families revealed a locus on chromosome 1 associated with oocyst shedding (logarithm of odds = 3.46). The genetic mechanism of this locus appeared additive. The genomic scan also identified three potential growth QTL on chromosomes 1, 6, and 8. These results provide the foundation for further investigation to validate the QTL.

Animals↗