Research On Epidemiology Of Quail Coccidiosis And Biological Characters Of Eimeria Uzura

Quail coccidiosis is a common disease,may cause great losses in quail breeding.In order to study the prevalence and identify species,a survey about housing quails coccidiosis was performed in Henan province from March to September in 2006.The results showed the infection rate of coccidium was very high in all areas that we observed,and average infection rate was 89.0%.Infection rate of coccidium was low in 1-18-day quails,was 5.8%.While it was high in 20-38-day quails and more than 50-day quails,was 92.5%,93.0%,respectively.Three species of the Eimeria were identified,namely,E.bateri,E.tsunodai and E.uzura.Moreover,E. bateri was the predominant species.There were difference of infective intensity in different ages and in different areas,but the total infective intensity was not high.Pure E.uzura was obtained by infecting 8 six-day male quails with single oocyst. And then the pure oocysts were amplified twice.Oocysts excreting regulation sporulate progress,morphological characteristic and parasitic site were observed during the experiments.The results showed that the biological characters of amplifing oocyst were concordant with E.uzura.The minimum sporulation time was 14 hours at 25～26℃,the sporulation rate was more than 80%at 16h.The oocysts excreting peak were significantly different between the two oocysts amplifying experiments.But the prepatent period and patend period were the same.Pathogenicity of the E.uzura which we isolated was not powerful.Two hundred male quails,8 days old,were divided into five groups at random. Groups were inoculated with 1.0×10~3,1.0×10~4,1.0×10~5,5.0×10~5 or 0 sporulated oocysts,respectively.The pathogenicity ofE.uzura,regularization of quails excreting oocysts and endogenous stages of the parasites were observed.The results discovered low-grade virulence;quails inoculated with oocysts exhibited outward signs,included depressed weight gains,bloody stools.A dose of 1.0×10~5 oocysts produced 6.67% mortality.Prepatent period was 5 days,patend period were more than 8 days,the peak of oocyst production occurred at DPI(day post inoculation)5～6and DPI 8～9.All generations of meronts and gametocytes located in the quails' chorioepithelium cell, mostly duodenum,a few in the upper jejunum.The result showed that E.uzura had 4 asexual and 1 sexual intra-intestinal conventional life cycle.According to the shape of mature meront and the number of merozoites in a meront,maybe two types meront existed.Mature first generation meronts which contained 3～5 first generation merozoites were found at 12h PI,the shape of first generation meronts was irregular, the average size was 4.8μm×3.8μm.First generation merozoites were crescent-shaped, 4.5μm×1.2μm.Second generation meronts were found at 60h PI.Each second generation meront formed 5～9 second generation merozoites which were 2.0μm×1.0μm in size.Third generation meronts were found at 90h PI and the total number of meronts increased obviously.The third generation meronts were oblong or spherical and the average size was 5.0μm×4.2μm.Each third generation meront generated dozens of merozoites which were banana-shaped,1.5μm×0.8μm in size. Fourth generation meronts were seen at 96h PI,the average size was 7.0μm×5.2μm. Fourth generation merozoites were seen at 102h PI,the average size was 2.8μm×1.4μm.Gametocytes were seen at 108～120h PI,macrogametocytes 12.3 (7.7～18.1)μm×9.0(5.2～12.9)μm;microgametocytes 5.3(2.6～7.7)μm×4.7μm (2.6～7.2)μm.Oocysts were found in intestinal contents and intra-intestinal epithelium cell at 114～120h PI.Pathological changes of intestinal tract were light and couldn't be observed easily at 6～84h PI.With the development and multiplication of coccidia,evident pathological changes were found at 96h PI,including epithelia degeneration and necrosis,inflammatory cell infiltrate in lamina propria,light hemorrhage and hyperemia of duodenum and upper jejunum.Even if low-dose group which inoculated 1.0×10~3 sporulated oocysts per quail,many developing coccidia could be seen in some epithelia at 102～120h PI,but atrophy of intestinal villus was not obvious in all groups.18SrDNA loci of E.uzura was amplified by nested-PCR and sequenced.11 nucleotide sequences were obtained through BLAST searching,aligned and phylogeny trees were constructed.The result indicated that topology of MP and NJ tree were uniformity essentially.Two phylogeny trees were reflected that E.uzura was a species.