Epizootiology of Sarcocystis infections in mule deer fawns in Oregon

From 1974 to 1977, 62 wild mule deer (Odocoileus hemionus) fawns from Steens Mountain, Ore were euthanatized in autumn (23 deer), winter (21 deer), and spring (18 deer). The number of sarcocysts of Sarcocystis spp was counted in histologic sections of various muscular organs. Sarcocysts were seen in the muscle specimens of 14 of the 23 deer euthanatized in autumn (September to November) and in specimens from all 39 deer euthanatized in winter (December and January) and spring (March and April). The sarcocyst burden was greatest in the spring (736/deer), less in the winter (150/deer), and least in autumn (12/deer). Most sarcocysts collected from 3- to 5-month-old deer in autumn were immature, whereas most sarcocysts collected from 9- and 10-month-old deer in the spring were mature. More sarcocysts were seen in sections of muscles from limbs than in those of tongue, esophagus, and other skeletal muscles; the fewest sarcocysts were seen in the heart. Degenerating sarcocysts were seen in deer examined in the spring, but not in deer examined in autumn and winter. Sarcocystis was the only infectious agent found in unthrifty deer fawns. Of the 18 fawns (6 in autumn, 1974; 6 in winter, 1974; and 6 in spring, 1975) examined for helminths, only mild infections were seen in the deer examined in the spring of 1975. From 1974 to 1977, from the Crooked Creek area of Oregon, 48 mule deer fawns (12 in autumn, 18 in winter, and 18 in spring) were euthanatized and evaluated for Sarcocystis infections.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hematology of experimental acute Sarcocystis bovicanis infection in calves. II. Serum biochemistry and hemostasis studies

Of four Holstein-Friesian calves infected with 200,000 sporocysts of Sarcocystis bovicanis, three become ill and died on days 35, 55, and 59 of a 63-day experiment. No control calves became ill or died. Serum biochemicals and hematologic indicators of hemostasis from both groups were measured throughout the experiment. Creatine phosphokinase values for both groups increased markedly during acute infection. Lactic dehydrogenase and aspartate aminotransferase values were high in infected calves on days 25 to 35 and days 24 to 63, respectively, indicating injury of muscle, liver, or other tissues. Sorbitol dehydrogenase values were significantly higher for infected than for control calves on days 25 and 35, indicating liver injury. Serum bilirubin and blood urea nitrogen values were significantly increased in three anemic infected calves from day 25 or 26 to day 35, probably reflecting destruction of erythrocytes. The fourth infected calf was not anemic and had no hyperbilirubinemia and only minimal azotemia. Serum protein and albumin values decreased in infected calves on days 21 to 30 or 35, when, although hypoalbuminemia persisted, total protein concentration increased. Glucose, calcium, sodium, and chloride values decreased in infected calves slightly before onset of illness and remained low throughout the experiment. Potassium, magnesium, and phosphorus values did not differ between infected and control calves. Activated partial thromboplastin time and Russell's viper venom time were normal; prothrombin time was significantly higher from day 27 to day 49 in infected calves. This pattern was interpreted as evidence for acquired factor VII deficiency. Abnormal retraction of blood clots and enlarged platelets in blood smears, which indicate platelet dysfunction and increased platelet turnover, respectively, were seen on days 27 through 35 in anemic infected calves. Values for thrombin time (three calves) and fibrin degradation product concentration (one calf) increased just before death of the infected calves.     

Histopathologic and immunohistochemical findings in two white-tailed deer fawns persistently infected with Bovine viral diarrhea virus.

Bovine viral diarrhea virus (BVDV) is an important pathogen of domestic cattle. Serologic, experimental, and individual case studies explored the presence and pathogenesis of the virus in wild ungulates; however, there remain large gaps in knowledge regarding BVDV infection in nonbovine species. Live twins were born from a white-tailed deer (Odocoileus virginianus) doe infected with noncytopathic BVDV during its first trimester of pregnancy. The twins died at 1 day of age from trauma unrelated to the infection, and tissues were collected for histologic and immunohistochemical examination. The most significant histologic abnormality was diffuse depletion of B-lymphocytes in both fawns. The BVDV antigen was distributed widely throughout many tissues and cell types, most notably epithelium and vascular endothelium, consistent with that reported in cattle. In contrast to cattle, lymphocytes exhibited only very rare positive staining.     

旱獭住肉孢子虫感染的调查

住肉孢子虫是球虫类的寄生原虫 ,其中某些种类为人兽共患的寄生虫 ,其宿主范围很广。目前已发现的住肉孢子虫约有 1 0 0多种。旱獭住肉孢子虫 ,尚无报道 ,本地区旱獭住肉孢子虫的感染情况报道如下。1　材料与方法1 .1　调查对象　来自天峻地区国家计划猎杀的 66只旱獭 ,在每只旱獭上采取膈肌、咬肌、心肌、骨骼肌作为被检肉样 ,编号待检。1 .2　调查方法　每份肉样 ,弃去包膜后沿肌纤维走向 ,分别剪取如燕麦粒大小肌肉薄块 2 4粒 ,排列于载皮片上 ,滴加 50 %甘油水溶液 ,盖上同一大小玻片一块 ,加压制成半透明压片 ,在生物显微镜下检查 ,发…     

Effect of intermittent oral administration of ponazuril on experimental Sarcocystis neurona infection of horses

OBJECTIVE: To evaluate the effect of intermittent oral administration of ponazuril on immunoconversion against Sarcocystis neurona in horses inoculated intragastrically with S neurona sporocysts. ANIMALS: 20 healthy horses that were seronegative for S neurona-specific IgG. PROCEDURES: 5 control horses were neither inoculated with sporocysts nor treated. Other horses (5 horses/group) each received 612,500 S neurona sporocysts via nasogastric tube (day 0) and were not treated or were administered ponazuril (20 mg/kg, PO) every 7 days (beginning on day 5) or every 14 days (beginning on day 12) for 12 weeks. Blood and CSF samples were collected on day - 1 and then every 14 days after challenge for western blot assessment of immunoconversion. Clinical signs of equine protozoal myeloencephalitis (EPM) were monitored, and tissues were examined histologically after euthanasia. Results: Sera from all challenged horses yielded positive western blot results within 56 days. Immunoconversion in CSF was detected in only 2 of 5 horses that were treated weekly; all other challenged horses immunoconverted within 84 days. Weekly administration of ponazuril significantly reduced the antibody response against the S neurona 17-kd antigen in CSF. Neurologic signs consistent with EPM did not develop in any group; likewise, histologic examination of CNS tissue did not reveal protozoa or consistent degenerative or inflammatory changes. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of ponazuril every 7 days, but not every 14 days, significantly decreased intrathecal anti-S neurona antibody responses in horses inoculated with S neurona sporocysts. Protocols involving intermittent administration of ponazuril may have application in prevention of EPM.     

Lipid metabolism and Sarcocystis miescheriana infection in growing swine.

Sixteen 2-month-old pigs were divided into four equal groups and infected with either 500,000, 1,000,000 or 3,000,000 sporocysts of Sarcocystis miescheriana. Four pigs served as uninfected controls. Pigs were bled weekly and serum was collected beginning 14 days prior to infection and continuing until 63 days after infection. Body fat composition, as measured by the specific gravity of the carcass, was not affected by infection. There were no significant effects of infection on serum concentrations of glucose, insulin, triglycerides, and total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol. A slight depression in HDL cholesterol occurred during the acute phase of infection. Tumor necrosis factor (TNF) was not detected in serum from infected swine when assayed by a cytotoxicity assay using TNF-sensitive WEHI 164 clone 13 cells. Attempts to stimulate TNF production in RAW 264.7 cells with parasitic lysates gave mixed results. This study suggests that the disruption of lipid metabolism is not the primary cause of growth retardation in growing swine infected with S. miescheriana.     

Lesions and transmission of experimental adenovirus hemorrhagic disease in black-tailed deer fawns

Adenovirus infection was the cause of an epizootic of hemorrhagic disease that is believed to have killed thousands of mule deer (Odocoileus hemionus) in California during the latter half of 1993. A systemic vasculitis with pulmonary edema and hemorrhagic enteropathy or a localized vasculitis associated with necrotizing stomatitis/pharyngitis/glossitis or osteomyelitis of the jaw were common necropsy findings in animals that died during this epizootic. To study transmission of adenovirus infection in deer and susceptibility of black-tailed deer (Odocoileus hemionus columbianus) fawns to adenovirus infection, six 3-6-month-old black-tailed fawns were divided into two treatment groups. One group was inoculated intravenously and the other group was inoculated through the mucous membranes of the eyes, nose and mouth with purified adenovirus. Each treatment group also included two additional fawns (four total) that were not inoculated but were exposed to inoculated animals (contact animals). One fawn served as a negative control. Between 4 and 16 days postinoculation, 8/10 fawns developed systemic or localized infection with lesions identical to lesions seen in animals with natural disease that died during the epizootic. Transmission was by direct contact, and the route of inoculation did not affect the incubation period or the distribution of the virus (systemic or the localized infection). Immunohistochemical analysis using polyclonal antiserum against bovine adenovirus type 5 demonstrated staining in endothelial cells of vessels in numerous tissues in animals with systemic infection and endothelial staining only in vessels subtending necrotic foci in the upper alimentary tract in animals with the localized form of the disease. All inoculated or exposed animals had staining in the tonsillar epithelium. Transmission electron microscopic examination of lung and ileum from two fawns with pulmonary edema and hemorrhagic enteropathy demonstrated endothelial necrosis and adenovirus virions in endothelial cell nuclei. Adenovirus was reisolated in black-tailed deer pulmonary artery endothelial cells using lung homogenate of the first fawn that developed systemic adenovirus infection. Serum virus neutralization test results suggest that this deer adenovirus is a new serotype.     

Unusual biphasic disease in domestic pigeons (Columba livia f. domestica) following experimental infection with Sarcocystis calchasi

A novel Sarcocystis species has recently been reported in the domestic pigeon (Columba livia f. domestica) as intermediate host, causing severe central nervous signs similar to Paramyxovirus-1 or Salmonella Typhimurium var. cop. infection. Transmission of the parasite via the northern goshawk (Accipiter gentilis) as definitive host has been established. Experimental infection of domestic pigeons with sporocysts excreted by experimentally infected northern goshawks reproduced the natural infection in the pigeon, proving the causative role of the parasite in the disease. Here, we describe in greater detail the course of the fulminant biphasic disease depending on the infectious dose. Pigeons infected with 10(3) or 10(4) sporocysts showed clinical signs of polyuria and apathy around 10-11 days postinfection (dpi) and sudden neurological signs 51-57 dpi as a second phase of disease. Pigeons infected with higher doses died within 7-12 dpi, also showing polyuria and apathy but without nervous signs. At necropsy, livers and spleens had multifocal necroses and infestations with parasitic stages, namely, schizonts. Moreover, lesions and schizonts were also found in the lung, bone marrow, and next to blood vessels in the connective tissue of various organs. Pigeons infected with 102 sporocysts remained symptomless until 58-65 dpi, when sudden central nervous signs occurred. Major histopathologic findings of pigeons with neurological signs were encephalitis and myositis of virtually every skeletal muscle with high infestations of sarcocysts. Only mild myocarditis and very few cysts were found in the heart muscles. Importantly, a sentinel pigeon developed identical lesions when compared to those of low-dose infected pigeons, suggesting a risk of mechanical transmission of sporocysts from freshly infected to uninfected pigeons in a flock. By contrast, chickens failed to develop any clinical signs or pathologic lesions in the same experiment. The findings further characterize the new highly pathogenic disease in domestic pigeons, which clinically mimics paramyxovirosis and salmonellosis in both phases of the disease and exclude chickens as further intermediate host species.     

Experimental Sarcocystis levinei infection in buffalo calves

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.     

Experimental infection with Sarcocystis medusiformis in sheep

The development of the parasite was studied in 48 sheep killed between 188 and 1132 days after experimental inoculation with Sarcocystis medusiformis sporocysts from cats. Immature sarcocysts were present at 188 days post inoculation (d.p.i.). At 331 d.p.i. macroscopic sarcocysts with an elongate fusiform appearance were seen in the laryngeal, abdominal and diaphragm musculature. The largest cyst measured 2 mm in length by 0.5 mm in width at 331 d.p.i.; histologically they contained metrocytes at the periphery of the cyst with more densely staining merozoites in the central region. By 443 d.p.i. typical 'thin' cysts 2-3.5 mm in length were seen in the flank and external thoracic muscles. By 765 d.p.i. sarcocysts were 5 mm in length. The ultrastructure of the cyst wall of these cysts resembled that of S. medusiformis. At 1132 d.p.i. sarcocysts measured 4 mm X 0.5 mm.     

Histopathologic evidence for parvovirus infection in dogs

Two dogs kenneled at a commercial establishment died of a disease manifested as severe hemorrhagic diarrhea. Histopathologic findings in both dogs bore a striking resemblance to those typical of feline infectious enteritis. Viral particles resembling members of the Parvoviridae family were observed in the contents of the small intestine of one of the dogs. The disease was similar to the recently recognized canine gastroenteritis associated with a parvovirus-like agent.     

Suspected Sarcocystis infection in an aborted bovine foetus

Extract

Sir:- Samples from a case of sporadic abortion, two weeks before term in a two-year-old heifer, were submitted to the Palmerston North Animal Health Laboratory. They consisted of fresh foetal stomach contents, fixed foetal lung, and maternal urine and serum. No significant pathogens were isolated from the stomach contents or urine and serological tests for brucellosis and leptospirosis were negative.     

Immunohistochemical and histopathological study of experimental rabies infection in mice.

An immunohistochemical and histopathological study using the ABC technique was carried out to examine time-sequential virus spread in the central nervous system (CNS) of mice after inoculation with the CVS strain of fixed rabies virus by different routes; intracerebral (ic), intraocular (io), intranasal (in), intramuscular (im) and subcutaneous (sc). Only the ic and io inoculations caused fatal infections, so that detailed analysis was conducted on mice inoculated by these two routes. In ic-inoculated mice, viral antigens were detected mainly in neurons in the cerebral cortex and in the pyramidal cells and granular cells of the hippocampus. After io inoculation, viral antigen was first detected in the trigeminal nerve ganglia, following which it spreads to the cerebral cortex and cerebellum. In the hippocampus only a few cells were viral antigen-positive at the early stage after io inoculation. There were no inflammatory lesions or Negri bodies in the CNS of mice infected by either route. This suggests that clinical signs such as ataxia or depression leading to death may be due to the direct effect of the virus on the functions of neural cells, but not to inflammatory reactions. The ABC method will be useful for the early diagnosis of suspected patients or animals to have the disease when conventional histopathological and immunofluorescent antibody techniques can not detect lesions or viral antigens.