鹌鹑源火鸡隐孢子虫生物学特性研究

利用鹌鹑源火鸡隐孢子虫（Cryptosporidium meleagridis）分别感染雏鸡、雏鸭、雏鸵鸟和小白鼠研究其致病性.结果能成功感染雏鸡、雏鸭和小白鼠,但不能感染雏鸵鸟.2个感染组雏鸡主要在感染后第3天引起雏鸡强烈的腹泻症状,但非免疫抑制组比免疫抑制组症状稍轻,此外,免疫抑制组的鸡出现了多个排卵囊高峰;感染相同剂量的2个试验组雏鸭的排卵囊显露期均较雏鸡短,非免疫抑制组雏鸭的排卵囊规律呈一过性,2组雏鸭均未出现明显的临床症状;免疫抑制组小白鼠出现多个排卵囊高峰,显露期持续24 d,正常组小白鼠的排卵囊规律呈一过性.根据肠黏膜涂片,抗酸染色观察发现主要虫体寄生于雏鸭的回肠;通过病理组织学切片和电镜观察发现虫体主要寄生于雏鸡的回肠和小白鼠的十二指肠,但均主要引起肠绒毛的大量脱落,黏膜上皮细胞肿胀,炎性细胞浸润.试验证明鸭为鹌鹑源C.meleagridis的新宿主,但敏感性较低;鹌鹑源C.meleagridis不感染非洲雏鸵鸟.发现鹌鹑源C.meleagridis在鹌鹑、鸡和鸭体内寄生部位与小鼠体内寄生部位有明显差异.     

火鸡隐孢子虫在鹌鹑体内发育史的研究

分离自鹌鹑的火鸡隐孢子虫经口感染２日龄鹌鹑，潜在期为３ｄ，开放期为４－１８ｄ。它在鹌鹑体内发育史过程为：卵巢经口接种后，于十二指肠，空肠，回肠肠腔中子孢子脱囊，至接种后６ｈ全部子孢子脱囊完毕。接种后６ｈ在小肠中出现滋养体。接种后１２ｈ在小肠中出现内含８个裂殖子的裂殖体及裂殖子，接种后４８ｈ滋养体和裂殖体开始出现于直肠。接种后５４ｈ，在小肠，直扬中出现含有１６个子弹形小配子的小配子体。小配子与大配子     

禽类隐孢子虫病的研究进展

隐孢子虫是个体较小的球虫类寄生虫,对人和其它多种脊椎动物都有严重的致病性.禽类隐孢子虫最早由Tyzzer于1929年报道,但当时并没有命名,因为该虫和寄生于鼠的C.muris相同.1955年,Slavin报道了一种寄生于火鸡体内的形态相似的寄生虫并命名为C.meleagridis.Current等于1986年在鸡体内分离到一种寄生虫,命名为C.baileyi.许多研究证明C.baileyi和C.meleagridis是2个单独虫种.不过,最近研究表明C.meleagridis与寄生于100多种哺乳动物的C.parvum接近.目前隐孢子虫的分类主要是根据卵囊形态、SSUrRNA序列相似性、宿主特异性和寄生部位.C.baileyi和C.meleagridis从卵囊形态上可以明显地区分开,而C.meleagridis和C.Parvum却很难分开.     

贝氏隐孢子虫在丝毛乌骨鸡体内发育的扫描电镜观察

使用扫描电镜观察了贝氏隐孢子虫(Cryptosporidium baileyi) 在丝毛乌骨鸡体内内生发育虫体的三维形态。大量球形虫体嵌于微绒毛丛中。滋养体呈球形,直径1.54～1.76 μm 。裂殖体呈桔瓣形或旋涡形排列,直径2.4～3.0 μm ,内含8 个香蕉形裂殖子,大小为4 μm ×0.65 μm 。成熟大配子体直径为3.5 μm 。带虫空泡内、外侧基部均可观察到梳状结构,根据带虫空泡的结构将其分为2 类,其中一类为裂殖子或小配子的带虫空泡,另一类为卵囊的带虫空泡。     

猪源隐孢子虫对仔猪致病性研究

为确定我国猪源隐孢子虫的危害性，采用光镜、扫描电镜和透射电镜等技术研究了猪源隐孢子虫sucp株对5日龄仔猪的致病性。结果：感染仔猪出现水样腹泻和脱水，粪便中混有肠黏膜碎片，潜伏期为3～5d，排卵囊持续期33-43d，虫体寄生于盲肠、结肠和直肠，并且盲肠和结肠杯状细胞增生，有炎性细胞浸润，结肠和直肠黏膜微绒毛萎缩、倒伏和脱落。结果表明sucp株对新生仔猪有一定致病性。     

河南省规模化鸡场隐孢子虫感染情况调查

隐孢子虫（Cryptosporidium）是一种引起人兽共患病的机会性原虫,能感染包括人在内的240多种动物,引起动物机体不同程度的消化道和呼吸道症状。目前已鉴定出16个有效种,40多个基因型。感染禽类的隐孢子虫主要有3个种：贝氏隐孢子虫（C.baileyi）、火鸡隐孢子虫（C．meleagridis）和鸡隐孢子虫（C．galli）。其中C．baileyi为感染鸡的优势虫种,主要寄生在鸡的喉头、气管、法氏囊、泄殖腔等部位;C．meleagridis主要寄生于小肠,属于人兽共患病原;     

不同禽源贝氏隐孢子虫分离株对鹌鹑致病性的比较研究

本研究旨在观察不同禽源贝氏隐孢子虫(Cryptosporidium baileyi)对鹌鹑的致病性差异。采用光镜、扫描电镜等技术研究了鸡源、鸭源、鹌鹑源、白文鸟源、鸵鸟源贝氏隐孢子虫分离株对10日龄鹌鹑的致病性。结果表明,感染鹌鹑均出现腹泻和呼吸道症状,排卵囊持续期11~18 d,虫体寄生于喉头、气管、法氏囊和泄殖腔。其中鸭源C.baileyi感染组鹌鹑发病率和死亡率分别为82.5%、25%,鸡源C.baileyi(郑州株)感染组发病率和死亡率分别为77.5%、12.5%,鹌鹑源C.baileyi感染组发病率、死亡率分别为37.5%和17.5%。本研究结果提示,不同禽源C.baileyi对鹌鹑有一定致病性,其致病性强弱存在差异。     

黄艾美球虫侵犯宿主组织的超微研究

利用透射电镜和扫描电镜相结合的技术对黄艾美球虫（E.flavescens）人工感染后的子孢子移动过程及被虫体寄生的宿主细胞形态学变化和粘膜形态学变化进行了观察。子孢子在进入小肠腺上皮过程中需白细胞介导，在白细胞内可发育成球形的滋养体，观察到有两个子孢子侵入同一白细胞的现象，但分别存在于各自的带虫空泡中，黄艾美球虫引起的肠粘膜损伤主要发生于感染177小时之后，其损伤主要表现在绒毛大片脱落，结缔组织裸露，表面可见到大量破损的孔洞及大量肠杆菌，被虫体寄生的腺上皮细胞基部膨胀，微绒毛脱落，细胞核膨大并部分包被虫体，有些细胞核裂解为二。     

贝氏隐孢子虫内生发育虫体的扫描电镜观察

贝氏隐孢子虫内生发育各阶段虫体寄生于气管和法氏囊的微绒毛丛中 ,鸭对贝氏隐孢子虫的易感性低于鸡和丝毛乌骨鸡。滋养体呈球形 ,平均直径 1 3μm ;typeⅠ裂殖体 ,平均直径 2 4μm～ 3 0 μm ,内含 8个裂殖子 ,呈逆时针旋涡状或呈桔瓣状排列 ;typeⅡ裂殖体内含 4个裂殖子 ,两种类型裂殖体的裂殖子之间填充着颗粒状残体并包围着一个大的球形残体。成熟裂殖子逸出的方式分为 4种类型。裂殖子大小为 3 0× 0 6 μm ,呈香蕉形。大配子体呈球形直径 3 3μm～ 4 2 μm ,小配子体直径为 3μm～ 3 6 μm。小配子呈子弹状 ,大小为 1 2 μm× 0 3μm ,并观察到成熟小配子的释放方式。带虫空泡可分为无球形残体和有球形残体两类 ,根据观察结果推测带虫空泡基部的梳状结构不具备营养器官的功能 ,营养器官应为带虫空泡的底部     

隐孢子虫病免疫学研究进展

隐孢子虫病（Cryptosporidiosis）是一种全球性的人畜共患病。其病原体为一种寄生性原虫，即隐孢子虫。隐孢子虫属于真球虫目、隐孢科、隐孢属，目前认为其有效种有6个，即感染鱼类的鼻隐抱子虫（C．nasorum）、感染爬行类的响尾蛇隐池子虫（C．crotati）、感染鸟类的火鸡隐抱子虫（C．meleagridis）和贝氏隐抱子虫（C．baileyi）、感染哺乳动物的鼠隐抱子虫（C．muris）和小隐子虫（C．parvum）。现已发现隐抱子虫可寄生于多种脊椎动物，下面就其引起的局部病理变化、免疫器官的反应、免疫反应和免疫诊断等方面述之。1寄生部位与所引起…     

Spontaneous cryptosporidiosis in an adult female rabbit.

An asymptomatic adult female rabbit had intestinal cryptosporidiosis. The ileum had blunted villi, a decrease in villus-crypt ratio and a mild edema in the lamina propria. Transmission electron microscopy showed the parasite to be a Cryptosporidium similar to those reported in mouse, guinea pig, lamb, calf, horse, monkey and man. This organism is referred to as Cryptosporidium cuniculus. Scanning electron microscopy on ileal mucosa showed altered intestinal microvilli in the attachment of the cryptosporidia. It is postulated that the organism was enveloped by the microvilli of the ileal epithelial cells which then fused and formed a continuous double membrane around the parasite.     

Variability in the localization of cryptosporidia in the intestines of spontaneously infected calves

31 to 37 localities were examined in the small and large intestines of 48 calves spontaneously infected with cryptosporidiosis. It was found that cryptosporidia occurred the most frequently in the distal part of small intestine, within the range of six metres of small intestine, in front of the ostium ileocecale (OIC); at the ileocecal valve the incidence of cryptosporidia dropped rapidly. In none case were the protozoans revealed in duodenum and in the adjacent four to six metres of proximal jejunum. The small intestine was invaded by cryptosporidia in a variable manner, in some cases a major part was continuously invaded, in other cases only one or two metres of distal jejunum without any changes in the ileum and vice versa. Approximately half the calves had cryptosporidia in the cecum, fewer cryptosporidia were found in the transverse colon. Cryptosporidia in the rectum were found in about 25% of cases. Some calves had cryptosporidia only in the large intestine. The intensity of the mucous membrane invasion varied: mass incidence of cryptosporidia was found only in caudal parts of small intestine, with high variability of the extent and with sudden cases of negative findings. In the large intestine only the cecum was invaded more intensively and in a diffusive manner, in the transverse colon and in the rectum the groups of parasites were usually found at the openings and in the wall of Lieberk uhn 's crypts.     

Pathogenesis of intestinal cryptosporidiosis in conventional and gnotobiotic piglets.

The pathogenesis of intestinal cryptosporidiosis was studied in 52 conventionally reared and 20 gnotobiotically reared piglets by inoculation with different doses of Cryptosporidium parvum oocysts. The prepatent period of C. parvum in both groups of animals were variable, depending on the number of oocysts administered. The patent period of C. parvum in conventionally reared piglets was 8 or 9 days; in gnotobiotic piglets cryptosporidia were found in feces until Day post infection (DPI) 16, when the last piglet was necropsied. Cryptosporidiosis in conventionally reared piglets is a self-limited diarrheal disease associated with morphological changes within the intestine. The most severe lesion was seen in the posterior jejunum and ileum from DPI 3 to DPI 7, and consisted of villous atrophy, crypt hyperplasia and inflammatory infiltration in the lamina propria. In gnotobiotic piglets cryptosporidia induced severe enterocolitis which occurred at least until DPI 16. The characteristics of enteric lesions were similar to those found in conventionally reared piglets. Intestinal cryptosporidiosis in both groups of animals shifted in the course of infection in the caudal direction and terminated in the large intestine. Examination by scanning electron microscope showed that infected absorptive cells had thicker and longer microvilli than those on non-infected cells; neighboring non-infected cells were hypertrophic, bulbously protuberant with minute microvilli with no distinct intercellular borders. Numerous cryptosporidia in the heterotopic glandular epithelium in the submucosa of cecum and colon on DPI 9 and 10 were found. No differences in the location and degree of cryptosporidial infection between colostrum-fed and colostrum-deprived conventionally reared piglets were found. Sow's colostrum does not appear to protect piglets from C. parvum infection. The role of intestinal microflora in the pathogenesis of cryptosporidiosis in piglets is discussed.     

Bovine Cryptosporidiosis: Clinical and Pathological Findings in Forty-two Scouring Neonatal Calves

Cryptosporidia organisms were identified in 42 of 161 (26%) neonatal, diarrheic calves, over a 32 month period commencing July 1979. Forty of the 161 calves were submitted alive and cryptosporidiosis was diagnosed in 63% (25 of 40) of them. The cryptosporidia infected calves were usually one to two weeks old and came from 26 herds where the typical history was profuse, watery diarrhea in nearly all neonatal calves. The diarrhea usually started around one week of age, was unresponsive to all conventional antidiarrhea therapies, lasted for two or more weeks and was usually fatal. Twenty-nine (69%) of the cryptosporidia infected calves were submitted between December and February. These calves were often hutch reared.

Histopatholoical examination revealed large numbers of the coccidial parasite Cryptosporidium sp embedded in the microvilli of jejunal and ileal absorptive enterocytes of all affected calves. The organisms were identified as trophozoites and schizonts (asexual stages) and macrogametes (female sexual stages) with the electron microscope. Microgametes (male sexual stages) were not identified. Occasionally a merozoite (asexual stage) was also seen apparently burrowing into or about to be enveloped by a host microvillus. Observation of the organisms was much easier when diarrheic calves were submitted alive. Enterotoxigenic Escherichia coli were often cultured from intestines of dead calves and occasionally from calves submitted alive. Coronavirus particles were seen in one calf. In the last year of this study, oocysts were identified in fecal smears stained with May-Grünwald-Giemsa stain and fecal samples using a dichromate solution flotation technique.

     

The significance of the incidence of coccidia of the Cryptosporidium species in the etiopathogenesis of neonatal diarrhea syndrome and enteritis in calves on the basis of simultaneous histopathologic and parasitologic studies

In 1985, a histopathological examination was conducted in the ileum and a parasitological examination in the ileum and rectum of 345 emergency slaughtered calves. The pathogenic role of cryptosporidia was compared in two groups of calves: group A contained 184 calves (53.3%) with scours and enteritis, group B contained 161 calves (46.7%) with other types of disease. In both groups the calves were divided into four age categories: 7 to 10 days (7.8%), 11 to 14 days (29.3%), 15 to 21 days (53.0%), 22 days and older (9.9%). During the parallel examination by both methods, cryptosporidia were detected in 124 cases, i.e. at the total invasion extensity of 35.93%; in group A the cryptosporidia were found in 76 cases (22.02%) and in the group B in 48 cases (13.91%). As indicated by the results, cryptosporidiosis is a disease of polyfactorial origin and cryptosporidia must be taken into account as one of the enteropathogenic factors in the etiology of scours. It is confirmed by the positive findings of cryptosporidia in the calves of group B (29.81%) and the negative finding in group A (31.3%) that no clear relationship was demonstrated to exist between the positive findings of these protozoans and the clinical symptoms of the diseases and enteritis. The pathogenesis of cryptosporidiosis includes significant regressive changes in the microvillous layer and enterocytes, which were a common finding at heavy invasions. The total positivity of the findings of cryptosporidia in the ileum was significantly higher (by 14.8%) during the histopathological examination, as compared with the parasitological examination. Out of the total positive findings, 39 cases (31.5%) were demonstrated histopathologically. During the parasitological examination, the positivity of the findings of cryptosporidia was higher by 4.3% in the rectum than in the ileum. When there was conducted a parallel parasitological examination of the ileum and rectum, the total positivity was higher by 7.5% than at the histopathological examination in the ileum. The highest invasion extensity was found at the age of 7 to 10 days in both groups of calves. The highest invasion intensity was found at the age of 11 to 21 days in both groups. The age until the 21st day when the parasitosis is intensively spread is considered as the most dangerous age of the calves from the epizootological point of view. Cryptosporidia occurred all the year round, no characteristic seasonal patterns were observed. The total average invasion extensity of the 24 farms from where the calves came was 42.3%, its range being from 0 to 85.7%.     

Renal Cryptosporidiosis (Cryptosporidium baileyi) in specific-pathogen-free chickens experimentally coinfected with Marek's disease virus

Renal Cryptosporidiosis was experimentally induced during a study to investigate the pathogenicity of Cryptosporidium baileyi in specific-pathogen-free (SPF) chickens coinfected with Marek's disease virus (MDV). Cryptosporidium baileyi was administered orally at 4 days of age to chickens previously infected at hatching (day 0) with the HPRS 16 strain of oncogenic MDV. Three control groups received MDV at hatching, C. baileyi on day 4, or placebo consisting of distilled water. Renal cryptosporidiosis lesions were induced in the group coinfected with MDV and C. baileyi. The kidneys were markedly swollen and pale, with visible urate crystals in the ureters and surface tubules. Oocysts of C. baileyi were demonstrated in six of seven cases tested by a scoring method with modified Sheather's sugar solution on renal tissue scrapings and were confirmed in three cases by histologic examination of paraffin-embedded kidney sections. Histologic study also revealed subacute interstitial nephritis, acute ureteritis, and attachment of cryptosporidia on the epithelial cell surface of the ureters and collecting ducts, collecting tubules, and distal convoluted tubules. Various developmental stages of the parasite were present in the kidney sections. To our knowledge, this is the first report of experimentally induced renal cryptosporidiosis in SPF chickens coinfected with MDV.     

Hexamita meleagridis (Spironucleus meleagridis) infection in chukar partridges associated with high mortality and intracellular trophozoites

An outbreak of infectious catarrhal enteritis, associated with the flagellated protozoan Spironucleus meleagridis (syn. Hexamita meleagridis), is reported from a commercial flock of chukar partridges in California. The disease affected birds between the ages of 4 and 6 wk and resulted in diarrhea, listlessness, depression, and high mortality. Concurrent infection with other intestinal pathogens, including Cryptosporidia, group E Salmonella, long-segmented filamentous microorganisms (LSFMOs), and Rotavirus-like virus particles, was found in some but not all affected birds. Dermatitis of the face, shanks, and feet, suggestive of B-complex vitamin deficiency, was present in most affected birds as well. Flagellated protozoan parasites could be found in the lumen of the duodenum and jejunum and in the intestinal crypts. In some cases the flagellates were wedged between epithelial cells or were located intracellularly within cells of the mucosal epithelium and the intestinal lamina propria.     

Morphological identification of cryptosporidia in the intestines of calves using light and scanning electron microscopy

Small and large intestines of ten calves of the age from 7 to 21 days, suffering from cryptosporidiosis were examined. It is recommended to perform the histopathological identification of cryptosporidia by prolongation of the basic staining with haematoxylin to one hour and by additional staining with tartrazine. Out of the special methods the most suitable are as follows: Wolbach's modification of Giems' staining method or staining with toluidine or polychromous blue. Mucopolysaccharides are in the granules and in the capsules of some developmental stages of cryptosporidia. By means of scanning electron microscope (SEM) cryptosporidia are clearly visible. As a rule, they are more or less immersed in the microvilli of enterocytes. In the intestines destructed by inflammation they occur even outside the epithelium, in the cases studied in the necrotic matter obstructing the outlets of the crypts of Lieberkühn in the caecum of the calves.     

Cryptosporidiosis in a pup

Cryptosporidiosis is a coccidian parasitism which has been implicated as a cause of diarrhea in man and a variety of animals. Cryptosporidiosis was diagnosed in a one-week-old pup which had a history of acute diarrhea. Organisms, 2 to 3 mm in diameter, covered the microvillous border of intestinal epithelium. Ultrastructurally, the cryptosporidia had one or more nuclei with prominent nucleoli and abundant cytoplasmic endoplasmic reticulum. Cryptosporidia may have played a role in the enteritis seen in this pup but further studies are needed to establish its pathogenicity.     

The homologous and interspecies transmission of Cryptosporidium parvum and Cryptosporidium meleagridis

Experimental infections have been performed in several mammals and birds to determine the host's specificity for Cryptosporidium parvum (of human and bovine origin) and for Cryptosporidium meleagridis (isolated from broiler chicken). The C. parvum infection (of human origin) was established also in calves (Bos taurus), lambs (Ovis aries), mice (Mus musculus), and rats (Ratus norvegicus), but not in broiler chickens (Gallus domestica). The C. parvum infection (of bovine origin), was achieved in calves, lambs, dogs (Canis familiaris), cats (Felis domesticus), rabbits (Orytolagus cuniculus), mice, rats, and guinea-pigs (Cavia porcelus) but not in broiler chickens. We have demonstrated that C. meleagridis can produce infection in broiler chickens and in 5 mammalian species (calves, pigs, rabbits, rats, mice) but not in guinea-pigs.