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Biomedical subjects

C C Norton

Publications and source records attributed to C C Norton.

At least 37 records · Page 2Linked to original sources
PubMed1983

The oocyst sporulation time of Eimeria species from the fowl.

Freshly isolated oocysts were sporulated at 29 degrees C with constant aeration. Minimum sporulation time was determined by dosing the developing oocysts at intervals of 1 h to successive groups of chickens to assess the first occurrence of infective forms. Microscopic analysis of the sporulating oocysts allowed calculation of the time required for 50% of the oocysts to complete the process. This was considered to be the most accurate determination and the most useful for comparative purposes. For 7 species of coccidia in the fowl, the 50% sporulation times were as follows: Eimeria acervulina 11.4 h; E. brunetti 38.3 h; E. maxima 38.1 h; E. mivati 19.0 h; E. necatrix 19.7 h; E. praecox 24.8 h; E. tenella 21.2 h.

Animals↗
PubMed1983

Eimeria mitis in mixed infections with E. acervulina and E. brunetti in the fowl.

Eimeria mitis and E. acervulina affect different areas of the intestine. Young chicks received E. mitis with or without E. acervulina in doses ranging from 2 to 128 X 10(4) oocysts. Mixed infections produced significantly more severe effects on growth than single infections of either species. The ratio of villus height to total mucosal thickness was reduced throughout the intestine in birds which received the mixed infection. E. mitis and E. brunetti affect the same area of the intestine. Single infections of E. brunetti in a range of doses from 1 . 25 to 20 X 10(3) oocysts produced a similar reduction in growth. When 20 X 10(3) oocysts of E. mitis were inoculated simultaneously, the effect on growth was not so severe and the oocyst output of both species was reduced. E. brunetti, superimposed 1, 2 or 3 days after an E. mitis infection, produced no greater effect on growth than E. mitis alone. Similarly, infections of E. mitis, superimposed on E. brunetti had no greater effect on growth than the latter species alone. Oocyst output of E. brunetti in superimposed infections was not reduced but peak output was delayed.

Animals↗
PubMed1983

Freedom of coccidial oocysts from Newcastle disease virus.

Oocysts were recovered from chickens experimentally infected with the Mukteswar strain of Newcastle disease virus and Eimeria acervulina or E tenella. Oocysts sterilised by sodium hypochlorite solution were washed, ruptured and inoculated into embryonating eggs which were examined after five days by the haemagglutination test for virus. All these tests were negative. Virus, initially detected with oocysts separated from faeces, was no longer present after sporulation in 2 per cent potassium bichromate. The B1 strain of virus survived for up to 30 hours in 2 per cent sodium hydroxide and 2 per cent potassium bichromate but was quickly destroyed by sodium hypochlorite (specific gravity 1.075).

Animals↗
PubMed1981

Anticoccidial drugs for preventive therapy in intensively reared pheasants.

A range of anticoccidial drugs was tested in young pheasants inoculated with three species of eimeria. Eimeria colchici, the most pathogenic species, was completely controlled by clopidol/methyl benzoquate and robenidine hydrochloride with the elimination of oocyst production. Clopidol and arprinocid gave good protection with reduced oocyst output and clopidol also adversely affected oocyst sporulation. Halofuginone and monensin were less effective. Amprolium hydrochloride/sulphaquinoxaline/ethopabate (ASE) and sulphaquinoxaline were ineffective. Both halofuginone and ASE controlled infections caused by E phasiani and E duodenalis. Halofuginone at 3, 6 or 9 ppm in the food produced no toxic effects in pheasants but growth rates of red-legged partridge chicks were retarded by concentrations of 3 and 6 ppm. Halofuginone protected young pheasants in a field trial in which sulphaquinoxaline was less effective.

Animals↗
PubMed1981

Scanning and transmission electron microscopy of Eimeria maxima microgametogenesis.

The structure and development of microgametocytes pf Eimeria maxima from chicks killed during the 6th day of infection were examined using transmission and scanning electron microscopy. Initially, nucleoli disappear and the surface of the microgametocyte invaginates. This is followed by a condensation of the chromatin which then lies at the periphery of the nuclei. Concurrent with this, the flagella are formed and they project into the parasitophorous vacuole and internal invaginations. Eventually, the nuclei become more dense and are seen to protrude from the periphery of the gametocyte. The surface view of mature microgametocytes consists of a large number of closely packed flagella.

Animals↗
PubMed1981

Ultrastructural changes in the macrogamete and early oocyst of Eimeria maxima resulting from drug treatment.

The ultrastructure of the macrogamete and developing oocyst of Eimeria maxima (Weybridge strain) was examined in the intestinal cells of chicks fed 3 different anticoccidial drugs. Amprolium at 125 p.p.m., arprinocid at 35 p.p.m. and dinitolmide at 250 p.p.m. caused considerable morphological abnormality and incomplete development of the wall-forming bodies of Type 2 (WFB II), which did not appear able to participate in oocyst wall formation. The wall-forming bodies of Type 1 (WFB I) were able in each case to participate in oocyst wall formation although amprolium and dinitolmide produced morphological abnormalities in them. In birds medicated with dinitolmide, the outer layer of the oocyst wall was formed initially at opposite poles of the macrogametes rather than as a uniform layer. Other abnormalities resulting from drug treatment are reported and some evidence that intravacuolar tubules may be formed by the parasite pellicle is presented.

Adenine↗
PubMed1981

Eimeria acervulina and E. mivati: oocysts, life-cycle and ability to develop in the chicken embryo.

Three strains of Eimeria acervulina and 3 strains of E. mivati were compared. E. acervulina was characterized by the ovoidal shape of its oocysts and their rapid sporulation, small first-generation schizonts containing few merozoites, and its inability to complete development in the chorio-allantois of chicken embryos. E. mivati had more rounded oocysts with a longer sporulation time, larger first-generation schizonts containing twice as many merozoites and it developed readily in the chorio-allantois. Pre-patent periods were variable but generally shorter with E. acervulina. A strain of E. mivati attenuated by repeated embryo passage showed a reduce pre-patent period.

Animals↗
PubMed1980

Studies with Eimeria acervulina and E. mivati: pathogenicity and cross-immunity.

Pathogenic effects caused by graded doses of recent isolates of Eimeria acervulina, E. Mivati and a new isolate, thought at first to be E. mitis, were compared. Cross-immunity studies were conducted with 3 strains of E. acervulina and 2 strains of E. mivati, together with the new isolate. The results showed marked similarities between E. mivati and the new isolate and clear distinctions between these and E. acervulina. E. mivati produced scattered petechiae but did not form discrete lesions in the intestine comparable to those seen with E. acervulina. Endogenous stages of E. mivati were most numerous in the lower small intestine and proximal caeca. The ratio of villus height to total mucosal thickness in the lower intestine was reduced. Similar changes caused by E. acervulina were seen in the anterior intestine only.

Animals↗
PubMed1979

Redescriptions of Eimeria irresidua Kessel & Jankiewicz, 1931 and E. flavescens Marotel & Guilhon, 1941 from the domestic rabbit.

Eimeria flavescens and E. irresidua from the domestic rabbit are redescribed. The relatively smaller ovoidal oocysts of E. flavescens which measure on average 31.7 X 21.4 micrometer, possess a wide micropyle at the broad end. First-generation schizonts of this species develop deep in the glands of the lower small intestine. Merozoites migrate to the caecum and colon where second, third and fourth-generation schizonts develop in the superficial epithelium followed by the fifth-generation schizonts and gametocytes which form in the glands. In young Dutch rabbits E. flavescens is very pathogenic; low doses of oocysts produce a severe enteritis with high mortality and morbidity. The larger, broadly ellipsoidal oocysts of E. irresidua measure on average 38.4 X 23.2 micrometer and often possess a very small cryptic oocyst residuum. The endogenous stages develop in the small intestine only; first-generation schizonts in the glands and second-generation schizonts in the lamina propria whilst third and fourth-generation schizonts and gametocytes develop in the villous epithelium. E. irresidua is not pathogenic in young Dutch rabbits; even heavy infections produce only a transient pause in weight gain.

Animals↗
PubMed1979

The species of Eimeria in rabbits for meat production in Britain.

Eight species of coccidia were recognized in 596 faeces samples from 3 commercial rabbitries in South East England. The level of infection was related to management methods and at one site it was reduced by an outbreak of mucoid enteritis and/or its treatment with oxytetracycline. In samples from rabbits managed conventionally in the wire cages over droppings-pits, 96% contained oocysts and of these, 60% had 1000-10000 oocysts/g. Mixed infections were common, 67% of the animals carrying 2-4 different species. Eimeria, media, E. magna and E. perforans occurred most frequently; E. coecicola, E. irresidua and E. flavescens were less common and E. intestinalis and E. piriformis were relatively rare. E. stiedai was not recorded.

Animal Feed↗
PubMed1978

The activity of methyl benzoquate and clopidol against Eimeria maxima: synergy and drug resistance.

Synergy between clopidol and methyl benzoquate against Eimeria maxima was shown to be supra-additive. Collateral sensitivity to these drugs could not be demonstrated in resistant lines of this parasite. Resistance to methyl benzoquate and clopidol was not transferred when lines of E. maxima, resistant to the respective drugs, were propagated together. The failure to demonstrate this phenomenon was judged not to be due to synergy between the drugs. Attempts to induce simultaneous was readily acquired by a line of E. maxima resistant to clopidol. Induced resistance to clopidol in a methyl benzoquate-resistant line required numerous passages.

Animals↗
PubMed1978

The appearance of bisporocytic oocysts of Eimeria maxima in drug-treated chicks.

A line of Eimeria maxima acquired resistance to Lerbek (a mixture of clopidol and methyl benzoquate) after serial passage against rising drug levels. Abnormal bisporocystic oocysts which appeared throughout this series were picked out individually and these produced infections in further groups of chicks. Serial passages of selected bisporocystic forms raised their proportion in oocyst yields to about 80% after 10-14 passages, but a few normal oocysts were still present.

Animals↗
PubMed1977

Eimeria stiedai in rabbits: the presence of an oocyst residuum.

Observations on 5 different isolates of Eimeria stiedai from pure infections in laboratory-reared rabbits have confirmed the presence of an oocyst residuum. This structure was seen in 89--100% of the oocytes in cultures prepared both from the liver and from the faeces at different times during the patent period. The residuum consisted of 1--7 or more granules situated centrally in the oocyst and partially concealed by 4 sporocysts. The differential diagnosis of E. stiedai and E. coecicola is discussed.

Animals↗