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1.
Equine protozoal myeloencephalitis (EPM) is a serious neurologic disease of horses in the Americas and Sarcocystis neurona is the most common etiologic agent. The distribution of S. neurona infections follows the geographical distributions of its definitive hosts, opossums (Didelphis virginiana, Didelphis albiventris). Recently, cats and skunks were reported as experimental and armadillos as natural intermediate hosts of S. neurona. In the present report, raccoons (Procyon lotor) were identified as a natural intermediate host of S. neurona. Two laboratory-raised opossums were found to shed S. neurona-like sporocysts after ingesting tongues of naturally-infected raccoons. Interferon-gamma gene knockout (KO) mice fed raccoon-opossum-derived sporocysts developed neurologic signs. S. neurona was identified immunohistochemically in tissues of KO mice fed sporocysts and the parasite was isolated in cell cultures inoculated with infected KO mouse tissues. The DNA obtained from the tongue of a naturally-infected raccoon, brains of KO mice that had neurological signs, and from the organisms recovered in cell cultures inoculated with brains of neurologic KO mice, corresponded to that of S. neurona. Two raccoons fed mature S. neurona sarcocysts did not shed sporocysts in their feces, indicating raccoons are not likely to be its definitive host. Two raccoons fed sporocysts from opossum feces developed clinical illness and S. neurona-associated encephalomyelitis was found in raccoons killed 14 and 22 days after feeding sporocysts; schizonts and merozoites were seen in encephalitic lesions.  相似文献   

2.
Sarcocystis species sporocysts were found in intestinal scrapings from 24 of 72 opossums (Didelphis virginiana) from rural Mississippi. The number of sporocysts in each opossum varied from a few ( < 100000) to 187 million. Sporocysts from 24 opossums were bioassayed for Sarcocystis neurona infections by feeding to gamma-interferon knockout (KO) mice. S. neurona was detected in the brains of KO mice fed sporocysts from 19 opossums by immunohistochemical staining with anti-S. neurona specific polyclonal rabbit serum, and by in vitro culture from the brains of KO mice fed sporocysts. The isolates of S. neurona from opossums were designated SN16-OP to SN34-OP. Merozoites from 17 of 19 isolates tested at the 25/396 locus were identical to previously described S. neurona isolates from horses. The high prevalence of S. neurona sparocysts in D. virginiana suggests that this opossum constitutes an ample reservoir of infection in the southern United States.  相似文献   

3.
Sarcocystosis was studied in 37 sheep after oral inoculation with 10(4)-5 x 10(7) sporocysts of Sarcocystis tenella from canine feces. Two sheep inoculated with 2.5 x 10(7) and 5 x 10(7) sporocysts became moribund 16 and 19 days post-inoculation (DPI), respectively, due to occlusion of arteries of gut and mesentery by first generation meronts. Sheep inoculated with 10(7) sporocysts remained clinically normal until 21 DPI and those inoculated with 10(5)-10(6) became ill 24-28 DPI due to anemia coincident with maturation of second generation meronts. Inflammation, hepatitis and myocarditis were the main lesions of acute and subacute ovine sarcocystosis. Inflammation began to subside by the time (75 DPI) sarcocysts matured. Sarcocystis-induced encephalitis was distinguished from naturally occurring myelomalacia in sheep caused by an unidentified sporozoan.  相似文献   

4.
Tissues (1 kg) from sheep, goats, cattle, moose, bison, or elk naturally infected with Sarcocystis species were fed to one to four Sarcocystis-free coyotes and the number of sporocysts in feces and intestines were counted. All 12 coyotes fed naturally infected tissues shed Sarcocystis in feces, with a prepatent period of 9 to 15 days. The four coyotes fed infected beef had 15, 25, 113, and 201 million sporocysts in their feces and intestines. The coyotes fed elk, moose, or bison had 2.5, 15, and 2.5 million sporocysts in their intestines, respectively. Sporocysts in feces of coyotes fed musculature of cattle, sheep, goats, and elk were structurally similar to those described previously from the feces of dogs. This is evidently the first report of the completion of life cycle of Sarcocystis species in moose and bison. Cross-transmission experiments indicated that one species of goat Sarcocystis completes its life cycle in both dog and coyote and that the ovine Sarcocystis is not transmissible to goats.  相似文献   

5.
驴肉孢子虫包囊的超微结构及其实验感染   总被引：2，自引：0，他引：2  
对昆明地区的26头驴进行了肌肉检查，在24头驴肌肉中发现了肉孢子虫包囊，其然自感染率为92．3％，光镜下包囊呈梭形，具有锥状和棍棒状的突起，透射电镜下突起内微管在顶端松散排列，向下延伸集结成束，斜伸入基质层，有的和母细胞的膜相连，用含有包囊的驴肉实验感染犬和猫各2只，感染后在犬粪便中发现孢子囊和卵囊，潜隐期为11－13 d，剖检在2只犬的小肠固有层中查到孢子囊和卵囊，猫粪便中一直未检到孢子囊和卵囊，剖检亦未发现，表明驴肉孢了虫的终末宿主要是犬，而是猫，研究认为驴全内的肉孢子虫仅有1种，鉴定为柏氏肉孢子虫（Sarcocystis bertrami).  相似文献   

6.
The objective of this study was to determine the amount and infectivity of porcine circovirus type 2 (PCV2) shed in nasal, oral and fecal secretions following experimental infection. Fecal, oral and nasal swabs and blood were collected at regular intervals until 69 days post-inoculation (DPI) from five PCV2-experimentally inoculated pigs (Trial 1). To assess the infectivity of the PCV2 present in excretions, secretions, and on a hypodermic needle, 26 PCV2-na?ve pigs (Trial 2) were inoculated with various samples obtained from Trial 1 pigs. In Trial 1, PCV2 DNA was detected in all sample types by 69 DPI. There were no differences in the amount of PCV2 DNA present in different sample types over time. In Trial 2, intraperitoneal inoculation with contaminated fecal, nasal and oral samples; intranasal inoculation of nasal secretions; and feces fed to na?ve animals resulted in viremia and seroconversion. Viremia and microscopic lesions were noted in one animal injected using a contaminated needle. In conclusion, experimental PCV2 exposure results in a long term infection. PCV2 is shed in similar amounts by nasal, oral and fecal routes and is infectious to na?ve pigs confirming that multiple routes of transmission are likely important in spread of PCV2 between pigs.  相似文献   

7.
The objectives of the study were to (a) develop a simple fecal progestin extraction and radioimmunoassay method to measure immunoreactive progestin in porcine feces and (b) to characterize fecal progestin profiles during the estrous cycle and postpartum. A simple extraction method was developed in trial 1 and the mean (+/- SD) progestin recovery of the method was 84.3 +/- 3.5%. Progesterone levels measured at five different spiked concentrations (50, 100, 200, 400, and 500 ng/0.5 g feces) showed no systematic error. The sensitivity of the assay was 0.16 nmol/L of the extract. Trial 2 involved collecting fecal samples from six cycling sows every second or third day, beginning on the day of estrus (day 0) and continuing until day 22. The mean (+/- SD) fecal progestin concentrations of these sows determined by the above assay during days 0-5, days 6-10, days 11-15, and days 16-21 were 87.1 +/- 17.5, 262.6 +/- 102.1, 1188.2 +/- 454.1, and 897.3 +/- 274.1 x 10(-3) nmol/g feces, respectively. In trial 3, fecal samples from six postpartum sows were collected at weekly intervals beginning from day 7 after farrowing until day 50. The mean (+/- SD) fecal progestin concentrations were 111.0 +/- 61.1, 74.1 +/- 21.3, 66.5 +/- 26.1, 122.7 +/- 58.8 and 533.5 +/- 244.2 x 10(-3) nmol/g feces, during days 7-10, days 11-20, days 21-30, days 31-40, and days 41-50 postpartum, respectively. The results indicate that simple fecal progestin extraction and assay are feasible alternatives to the standard blood progesterone assays for monitoring reproductive function in swine.  相似文献   

8.
Sarcocystis infections in Georgia swine   总被引：1，自引：0，他引：1  
Tissues from 168 mature sows obtained at slaughter in northern and southern Georgia were examined for infection with Sarcocystis spp. Digestion techniques revealed zoites in 28 (16.5%) sows. Infected meat was fed to laboratory-reared dogs, cats, raccoons (Procyon lotor), and opossums (Didelphis marsupialis). Dogs and raccoons shed sporocysts (8.3 mum X 11.2 mum) 12 to 14 days after infection. Cats and opossums were refractory to infection. Sarcocystis-free pigs were infected with 50,000 sporocysts of swine-dog origin. Tissues from laboratory-infected swine were fed to dogs and raccoons. Both species shed sporocysts 14 days later. This is the 1st time in which a definitive host has been demonstrated for species of Sarcocystis occurring in North American swine. The raccoon constitutes a new definitive host for S suicanis Erber 1977. In contrast to previously reported low prevalences of Sarcocystis infections in swine, the relatively high prevalence reported here indicates that S suicanis may be of importance to swine producers in Georgia.  相似文献   

9.
A marked reduction in the faecal excretion of sporocysts was observed in experimental pups, following the repeated oral administration to them of buffalo cardiac muscle infected with Sarcocystis levinei. Sporocysts excreted from days 9 to 25 post-infection (pi) exhibited a gradual reduction in the quantum. Maximum intensity of excretion of sporocysts was recorded between days 9 and 16 pi, becoming moderate after day 16, light after day 21 and completely absent after day 36. After the subsequent feeding to pups of S. levinei infected buffalo cardiac tissues at 40 day intervals the quantity of sporocysts shed was less, the prepatent period was prolonged and the patent period was considerably shortened. The peak period of excretion varied depending upon the number of exposures of the pups to the infected S. levinei tissues from buffaloes (Bubalus bubalis).  相似文献   

10.
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.  相似文献   

11.
From April 1996 to December 2002 the prevalence of Sarcocystis neurona sporocysts in North American opossum (Didelphis virginiana) in Southern Michigan was estimated. Sporocysts of S. neurona were found in intestinal scrapings from 31 (15%) of 206 examined opossum. The frequency of infection was higher in adult animals (26/206; 12.6%) and females (19/206; 9.2%) than in juveniles (5/206; 2.4%) and males (12/206; 5.8%). Also, prevalence of S. neurona sporocysts in opossums in relation to factors such as age, sex, season, body condition, presence of concomitant infection, and presence of young in the pouch of females was studied in detail over the course of the year, 2002. Univariate analyses identified the following factors as being associated with the presence of S. neurona sporocysts in opossums: (i) for age, adult (odd ratio [OR] = 2.074, P = 0.0005); (ii) for sex, female (OR = 7.016, P = 0.0119); (iii) for season, summer (OR = 7.917, P = 0.0032) and spring (OR = 4.071, P = 0.1063); (iv) for body condition, poor (OR = 3.50, P = 0.1200) and good (OR = 1.167, P = 0.8637); (v) for the presence of concomitant infection (OR = 23.056, P = 0001), and (vi) for the presence of young in the pouch of females (OR = 40.083, P = 0.0001). Multivariate logistic-regression analyses selected the following factors as being significantly associated with presence of S. neurona sporocysts in opossums: (i) for the presence of concomitant infection (OR = 8.722, P = 0.0160) and (ii) for the presence of young in the pouch of females (OR = 31.915, P = 0.0065). The prevalence of S. neurona sporocysts in D. virginiana suggests that this opossum may constitute an ample reservoir of infection to other animals in the northern United States.  相似文献   

12.
Six buffalo calves were orally inoculated with 3 graded doses of sporocysts of Sarcocystis levinei (0.5, 1.0 and 2.0 million sporocysts; 2 calves for each dose) while two more calves were kept as uninoculated controls. One calf from each group was killed at 30 days post infection (DPI) and the other at 80 DPI. Inoculated calves showed a dose dependent response. The calves inoculated with 0.5 and 1.0 million sporocysts did not manifest any clinical signs of disease up to 80 DPI. One of the two calves inoculated with 2.0 million sporocysts showed clinical signs of weakness, emaciation and anaemia during the 5th week post infection. The other calf remained healthy until it was killed at 30 DPI. Pale liver tissue, gelatinization of fat and haemorrhages in the heart were observed in one calf inoculated with 2.0 million sporocysts; only microscopic lesions were seen in other calves. Schizonts and merozoites were not observed in any calf. Mature sarcocysts were observed in cardiac and skeletal muscle of calves killed at 80 DPI whereas no sarcocysts were seen in calves killed at 30 DPI.  相似文献   

13.
Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM) in horse in the Americas. The only known definitive host for this parasite in the United States is the opossum (Didelphis virginiana); however, despite the importance of the disease, the epidemiology of the parasite in the definitive host is poorly understood. To begin addressing these data gaps, potential risk factors were evaluated for their association with the presence of sporocysts of S. neurona in opossums live-trapped in March 1999 and November 1999 to May 2000. Sporocysts of S. neurona were found in 19 of the 72 animals examined. Potential risk factors evaluated were locality, trap date, age, gender, the presence of young in the pouch of females, and body condition score. Variables that were associated with the presence of S. neurona sporocysts were used in logistic regression analysis. Of the factors examined, season and body condition score were associated with increased odds of an animal harboring sporocysts.  相似文献   

14.
Neurologic disease in horses caused by Sarcocystis neurona is difficult to diagnose, treat, or prevent, due to the lack of knowledge about the pathogenesis of the disease. This in turn is confounded by the lack of a reliable equine model of equine protozoal myeloencephalitis (EPM). Epidemiologic studies have implicated stress as a risk factor for this disease, thus, the role of transport stress was evaluated for incorporation into an equine model for EPM. Sporocysts from feral opossums were bioassayed in interferon-gamma gene knockout (KO) mice to determine minimum number of viable S. neurona sporocysts in the inoculum. A minimum of 80,000 viable S. neurona sporocysts were fed to each of the nine horses. A total of 12 S. neurona antibody negative horses were divided into four groups (1-4). Three horses (group 1) were fed sporocysts on the day of arrival at the study site, three horses were fed sporocysts 14 days after acclimatization (group 2), three horses were given sporocysts and dexamethasone 14 days after acclimatization (group 3) and three horses were controls (group 4). All horses fed sporocysts in the study developed antibodies to S. neurona in serum and cerebrospinal fluid (CSF) and developed clinical signs of neurologic disease. The most severe clinical signs were in horses in group 1 subjected to transport stress. The least severe neurologic signs were in horses treated with dexamethasone (group 3). Clinical signs improved in four horses from two treatment groups by the time of euthanasia (group 1, day 44; group 3, day 47). Post-mortem examinations, and tissues that were collected for light microscopy, immunohistochemistry, tissue cultures, and bioassay in KO mice, revealed no direct evidence of S. neurona infection. However, there were lesions compatible with S. neurona infection in horses. The results of this investigation suggest that stress can play a role in the pathogenesis of EPM. There is also evidence to suggest that horses in nature may clear the organism routinely, which may explain the relatively high number of normal horses with CSF antibodies to S. neurona compared to the prevalence of EPM.  相似文献   

15.
Laboratory-reared dogs were fed moose musculature infected with Sarcocystis alceslatrans. These dogs shed sporocysts [15.6 X 11.4 microns (14.4 to 15.8 X 10.8 to 11.5)] 11 to 15 days after inoculation. The prepatent period was 10 to 14 days. Two cats and 1 coyote that also ate infected moose musculature did not pass sporocysts. Histologic examination of intestinal tissue from experimentally infected dogs revealed microgamonts, macrogametes, and oocysts. All stages were present in the lamina propria of the small intestine, usually in the luminal third of the villi. Infections were concentrated in the proximal half of the small intestine. Oocysts were first noticed in dogs killed 7 days after inoculation and a sequence of sporogonic development occurred in dogs killed on subsequent days. Ultrastructural observations were made on the oocyst and sporocyst walls during sporogony.  相似文献   

16.
Surface epithelium of intercaruncular endometrium in pluriparous cows, crossbreds of Bohemian Pied cattle with Holstein-Friesian cattle, was not coherent until day 15 after parturition, with a variable height of cells (16-64 microns). Oedematous nature of lamina propria was subsiding gradually. From day 15 to day 20 after parturition the cell height of coherent surface epithelium and uterine glands became equable and stabilized (16-32 microns), and the lamina propria assumed its cellular nature with marked infiltration of polymorphonuclears and lymphocytes. Noticeable symptoms of atresia were demonstrated to occur more frequently in ovaries in the follicular population until day 15 after parturition. From day 10 to day 25 after parturition an increasing occurrence of luteinized follicles with diameters of maximally 3 mm was demonstrated.  相似文献   

17.
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.  相似文献   

18.
Eosinophilic enteritis (EOE) is a type of inflammatory bowel disease and is characterized clinically by chronic obstinate diarrhea. Three Japanese Black (JB) fattening cattle (2 males and 1 female) on different cattle farms presented with chronic episodic diarrhea without fever or dehydration. Soft reddish spherical carneous tissues (1−3 cm) were occasionally excreted within the diarrheic feces. Administration of antibiotics, antidiarrheal drugs and vermicides had no therapeutic effect, but dexamethasone improved the fecal characteristics. The symptoms persisted until the animals were slaughtered at 27–30 months of age. Histopathological examination of the intestines revealed marked eosinophilic infiltration in the lamina propria and submucosa. From these findings, we diagnosed these cattle as the first cases of EOE in JB cattle.  相似文献   

19.
Eight female, 12- to 34-month-old, specific-pathogen free cats were inoculated orally with Toxoplasma gondii cysts on day 0, then with Isospora felis and Isospora rivolta oocysts on day 39, and cysts of Hammondia hammondi on day 86 after inoculation with Toxoplasma. All cats shed oocysts of all 4 of these coccidia within 11 postinoculation days. The female cats were caged with 4 male Toxoplasma-free cats, starting 66 days after inoculation with Toxoplasma, until they were 5 to 6 weeks pregnant. Kittens that were born were housed with their mothers until necropsied or weaned. One 42-day-old kitten shed T gondii oocysts in feces. It was necropsied 2 days later and asexual stages of Toxoplasma (types D and E), gametocytes, and oocysts were demonstrated in sections of superficial epithelial cells of its small intestine. Lesions or forms of Toxoplasma were not demonstrated histologically in tis extraintestinal organs. Toxoplasma was not isolated from feces or tissues of the remaining 47 kittens born to these 8 queens. Toxoplasma was not isolated from the 4 male cats that were caged with infected females for 53, 59, 217, and 217 days. The source of toxoplasma infection in the kitten remained unknown but was considered unlikely to be congenital or through fecal contamination. Oocysts of I felis, I rivolta, and H hammondi were not found in the feces of any kittens, indicating that these coccidia are unlikely to be transmitted congenitally.  相似文献   

20.
Sarcocystis sporocysts from the intestines of four opossums (Didelphis albiventris) from Argentina were identified as Sarcocystis falcatula based on schizogonic stages and pathogenicity to budgerigars (Melopsittacus undulatus). Seven budgerigars fed sporocysts from the opossum feces died of acute sarcocystosis 8, 9, 11, 12, and 14 days after inoculation. Schizonts and merozoites found in the lungs and other organs of the budgerigars were identified as S. falcatula based on structure and immunoreactivity with S. falcatula-specific antibody. Sarcocystis falcatula was also isolated in bovine monocyte cell cultures inoculated with lung tissue from a budgerigar that died nine days after ingesting sporocysts. Two budgerigars inoculated subcutaneously with 1,000,000 culture-derived S. falcatula died 11 and 12 days post-inoculation. This is the first report of S. falcatula infection in South America.  相似文献   

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