Additional details of the life history of the chicken coccidium Eimeria mitis Tyzzer, 1929

Four asexual generations of Eimeria mitis were identified. The first three developed above the epithelial cell nuclei, but the fourth developed above and below. Meronts measured 13.8 x 16.4 microns, 16.1 x 16.4 microns, 12.1 x 14.6 microns, and 9.5 x 12.4 microns, respectively, of generations 1, 2, 3, and 4. They matured at 36, 67, 72, and 88 hr postinoculation (PI) and contain 20-24, 16-20, 10-14, and 7-10 merozoites, respectively. Merozonts measured 7.2 x 1.9 microns, 8.5 x 2.5 microns, 9.6 x 2.0 microns, and 6.75 x 2.75 microns, respectively. The first two types of meronts were deep in the crypts and epithelial cells. The third and fourth types of meronts were along the side and tip of the villi. Gametocytes developed from third and fourth generation. Gamonts were usually below the nuclei of the epithelial cells. Parasitism was primarily in the ileum, ceca, and rectum and also in the yolk-sac diverticulum.     

Life cycle of Eimeria krijgsmanni-like coccidium in the mouse (Mus musculus)

Life cycle of Eimeria krijgsmanni-like coccidium isolated from the feces of naturally infected mice purchased from commercial sources was examined. The parasite was purified by single oocyst isolation and maintained by passage in the mice before experiments. The sporulated oocysts were ovoid or ellipsoid, measuring 19.3 x 14.8 microm on average. One or two small polar granules were present. Micropyle and oocyst residuum were absent. Sporocysts were ellipsoid, measuring 11.6 x 7.2 microm on average with a small Stieda body and sporocyst residuum. Six groups of respective 5 mice (4-week-old) were inoculated with doses varying from 2.0 x 10(1) to 10(6) oocysts. All the mice examined began to shed oocysts from 7 day postinoculation (PI) and their maximum number of oocysts per gram of feces were 10(6) on day 8 PI. Patency was 6 or 7 days. This parasite had severe virulence to the mice that is, the mice given 10(6) oocysts showed anorexia, diarrhoea and rough hair from 1 day and all of them died on day 3 PI. The mice given 10(3) or more oocysts showed the clinical signs described above from day 5 and 4 of them received 10(5) died on day 9 or 10 PI. The parasites occurred within the epithelial cells of cecum, colon and rectum of infected mice. Sporozoites, 13.9 x 3.0 microm, with two large refractil bodies on side of the nucleus located subcentrally were observed on day 1 and 2 PI. Merozoites were first observed at 24 hr PI, and sexual stages were found from 4 day PI. No parasites were detected in the small intestine and mecenteric lymph nodes.     

Relative virulences of a drug-resistant and a drug-sensitive strain of Eimeria acervulina, a coccidium of chickens

The virulence of a field strain of the chicken coccidian parasite Eimeria acervulina (Boreham I), dually resistant to the chemically unrelated anticoccidial agents decoquinate and clopidol, was compared with that of a drug-sensitive laboratory strain (Ongar) of the same species. Following a single heavy infection (prevented from recycling), both strains exhibited pathogenic effects typical of their species, viz., pathognomonic lesions, adverse effects on body weight gain and feed conversion ratio (FCR), but no mortality. One week after infection, chicks infected with either strain had a statistically significantly worse weight gain than the uninfected control; the Boreham I strain produced more oocysts, and caused slightly more severe duodenal lesions and poorer FCRs than the Ongar strain (all those effects being non-significant). After 3 weeks, there were no significant differences between any cumulative effects of either strain, nor any differences from the uninfected control. However, from 2 to 3 weeks after infection, chicks infected with either strain had a greater feed consumption and growth rate than uninfected chicks. When chicks reared on solid floors were given lighter infections of either strain, which were allowed subsequently to recycle naturally, there were no consistent reductions in weight gains, but feed consumption was higher than that of uninfected chicks. Whatever, the mode of infection, there were no significant differences between the weights of infected and uninfected chicks after 3 weeks, but the FCR of infected chicks was usually poorer than that of uninfected chicks. The difference between the virulences of the Boreham I and Ongar strains was not greater than that between various drug-resistant strains or between various sensitive strains of several Eimeria species recorded in the literature. It is therefore concluded that there was no difference between the virulences of the two strains of E. acervulina that could be attributed to the drug-resistance of one of them.     

Course of the endogenous developmental phase of selected Eimeria species in pheasants

The localization and duration of developmental stages of Eimeria colchici and Eimeria duodenalis were studied histologically. The prepatent period of the most pathogenic species from the caeca of pheasants – Eimeria colchici – was 6 days. The patent period began on the 7th day and finished on the 11th day post-infection with the maximum production of oocysts on days 8–9. In the case of Eimeria duodenalis the prepatent period was shorter – 4 days, and the duration of the patent period was 3–4 days without a significant increase in oocyst production.     

Antibody response against endogenous stages of an attenuated strain of Eimeria tenella

The application of attenuated vaccines for the prevention of chicken coccidiosis has increased exponentially in recent years. In Eimeria infections, protective immunity is thought to rely on a strong cell mediated response with antibodies supposedly playing a minor role. However, under certain conditions antibodies seem to be significant in protection. Furthermore, antibodies could be useful for monitoring natural exposure of flocks to Eimeria spp. and for monitoring the infectivity of live vaccines. Our objective was to investigate the chicken antibody response to the different parasite life cycle stages following infection with an attenuated strain of Eimeria tenella. Western blotting analysis of parasite antigens prepared from the lining of caeca infected with the attenuated strain of E. tenella revealed two dominant antigens of 32 and 34 kDa, apparently associated with trophozoites and merozoites that were present at high concentrations between 84 and 132 h post-infection. When cryosections of caeca infected with E. tenella were probed with IgY purified from immune birds the most intense reaction was observed with the asexual stages. Western blotting analysis of proteins of purified sporozoites and third generation merozoites and absorption of stage-specific antibodies from sera suggested that a large proportion of antigens is shared by the two stages. The time-courses of the antibody response to sporozoite and merozoite antigens were similar but varied depending on the inoculation regime and the degree of oocyst recirculation.     

The development of the lesions caused by second generation schizonts of Eimeria necatrix.

First generation merozoites of Eimeria necatrix were found in epithelial cells of the crypts of Lieberkühn of chicks cells appeared to migrate into the lamina propria, forming nests of second generation schizonts that extended from the external muscularis to the lamina propria of the mid-villus. On the fourth and fifth days the mature schizonts, usually still within the infected cells were dishcarged into adjacent crypts. The muscularis mucosa appeared to be repaired by the formation of new, smooth muscle cells that spliced the broken ends of the ruptured muscle. 'Ghosts' of schizonts were found in the lamina propria on the sixth day after infection.     

斯氏艾美耳球虫感染对兔肝脏和血清抗氧化功能的影响

为研究斯氏艾美耳球虫对兔肝脏及血清抗氧化功能的影响,本实验以30日龄～45日龄兔为研究对象,测定兔接种斯氏艾美耳球虫后,血清和肝脏中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)和过氧化氢酶(CAT)的活性及丙二醛(MDA)含量。结果表明:感染斯氏艾美耳球虫后,SOD、CAT和GSH-Px的活性均有不同程度的下降,MDA含量高于对照组水平,各指标在感染急性期后逐步回升至对照组水平。表明病理氧化应激参与了球虫感染过程,损伤了机体的抗氧化平衡,同时其变化规律也符合球虫自限性感染的特点。     

Effect of lasalocid on the development of Eimeria tenella in chicken embryos

Sporozoites of Eimeria tenella were treated with lasalocid in vitro and their viability tested by inoculating them into the allantoic cavity of 11-day-old chicken embryos. Concentrations of 0.1, 1.0 and 10.0 micrograms ml-1 reduced sporozoite viability, as judged by oocyst production. Injections into the embryos of 5, 50 or 500 micrograms of lasalocid 92-93 h after infection also reduced oocyst production, indicating activity against the later stages of the life cycle.