Prevalence, transmission, and pathogenicity of Sarcocystis gigantea of sheep

Between March and May 1983, tongues and esophagi of 355 adult ewes from Colorado and Idaho were examined for grossly visible sarcocysts. Sarcocysts of Sarcocystis gigantea were found in 35 sheep. Cats fed sarcocysts from these naturally infected sheep shed sporocysts in their feces. Two adult ewes and 12 lambs inoculated with 1,000 to 1,000,000 sporocysts were euthanatized at postinoculation days (PID) 146, 230, 265, 391, 721, and 882, and their tissues were fed to Sarcocystis-free cats. All inoculated sheep remained clinically normal except for mild pyrexia between PID 12 and 18. Sarcocysts first became grossly visible at PID 391 and sarcocysts from sheep first became infectious for cats at PID 230.     

Serologic prevalence of toxoplasmosis in cattle, sheep, goats, pigs, bison, and elk in Montana

Serum samples from 2,539 cattle, 649 sheep, 123 goats, 413 pigs, 93 bison, and 56 elk from Montana were examined for antibody to Toxoplasma gondii in the Sabin-Feldman dye test or the modified agglutination test (MAT). Cattle, bison, and elk serum samples were treated with 0.2 M-mercaptoethanol before examination in MAT. In the dye test, 13.2% of sheep, 5.0% of pigs, and 22.7% of goats had antibody at a dilution of greater than or equal to 1:16. In the MAT, 3.2% of cattle, 3.1% of bison, and none of the elk were positive at a dilution of greater than or equal to 1:128.     

Sarcocystis Infection in Sheep from South-Western Norway

The occurrence of Sarcocystis infection and pathological changes were recorded in samples of the heart, diaphragm, and oesophagus from 198 healthy sheep representing 3 different age groups, obtained from an abattoir.The infection rate of S. gigantea (syn. S. tenella) was 18.2 %, and the distribution within groups was: ewes 30.0 %, yearlings 11.6 %, lambs nil. The infection rate of S. tenella (syn. S. ovicanis) was 65.1 %, and the corresponding distribution was: ewes 83.5 %, yearlings 74.4 %, and lambs 25.0 %. A third type of Sarcocystis sp. displaying thick wall was found in 3 samples.Focal interstitial infiltrates of mononuclear cells were demonstrated in 47.9 % of the hearts, in 19.6 % of the diaphragms and in 31.3 % of the oesophagi. The occurrence of Sarcocystis and the focal interstitial mononuclear cell infiltrates were positively correlated (P < 0.0001). Morphologically identical sporocysts typical of S. tenella were produced by dogs and foxes fed naturally infected sheep tissues. A cat fed S. gigantea macrocysts produced sporocysts characteristic for the species.Sarcocystis; pathology; life cycle; final hosts; sheep.     

Hosts of two canid genera, the red fox and the dog, as alternate vectors in the transmission of Sarcocystis tenella from sheep

Microscopic sarcocysts recovered from naturally infected sheep were infective to both the domestic dog (Canis familiaris) and the red fox (Vulpes vulpes). The parasite was passaged through experimental specific-parasite-free (SPF) sheep three times: infection was transmitted twice with sporocysts from foxes and subsequently with sporocysts from dogs. The sarcocysts from sheep muscle were infective to both dogs and foxes on each occasion. A cat was not infected. The prepatent period in individual canids ranged from 7 to 15 days. Sporocyst excretion was still detectable 60 days post infection. This study establishes that canids of two genera may act as vectors for a single isolate of the same Sarcocystis species from sheep.     

Development of Sarcocystis alceslatrans Dubey, 1980, in the small intestine of dogs

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.     

Development of sarcocysts of Sarcocystis levinei in water buffalo infected with sporocysts from dogs

Half a million sporocysts of Sarcocystis levinei obtained from experimentally infected dogs were fed to a buffalo calf, and sarcocysts of this species were recovered from its oesophageal muscles when the animal was killed on the 62nd day of inoculation, thus establishing a buffalo-dog-buffalo cycle.     

Bovine tuberculosis in Canadian wildlife: An updated history

Mycobacterium bovis infection in wild animals attracted little attention in Canada until the disease was almost eliminated from domestic livestock. Tuberculosis was endemic in plains bison and occurred in elk, moose, and mule deer in Buffalo National Park (BNP), Alberta during the 1920s and 1930s. Bison were moved from BNP to Wood Buffalo National Park (WBNP), where tuberculosis became, and remains, endemic in bison, posing a risk to efforts to restore bison in northern Canada. Tuberculosis was found in a white-tailed deer in Ontario in 1959, and in an infected elk near Riding Mountain National Park (RMNP), Manitoba in 1992. Intense surveillance has resulted in detection of 40 elk, 8 white-tailed deer, and 7 cattle herds infected between 1997 and 2008 in the RMNP area. The strains of M. bovis in the RMNP area are different from strains tested from cattle and bison elsewhere in Canada. Management of tuberculosis in cattle and wild animals is challenging because of uncertainty about the ecology of the disease in various species, difficulty in obtaining samples and population data from wildlife, lack of validated tests, overlapping jurisdictions and authority, and conflicting values and opinions among stakeholders.     

Lesions in sheep inoculated with Sarcocystis tenella sporocysts from canine feces

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.     

IS SARCOCYSTIS TENELLA TWO SPECIES?

When mutton containing microscopic sarcocysts of Sarcocystis spp was fed to dogs and cats, only dogs excreted sporocysts in their faeces. Conversely, mutton containing macroscopic sarcocysts produced infection in cats but not dogs. Sheep were experimentally infected with sporocysts from the faeces of dogs and cats either separately or together, and reciprocal feeding trials with their meat carried out with dogs and cats. The results of the experiments strongly suggest that Sarcocystis tenella of sheep may be 2 distinct species, one with the cat as definitive host, and the other parasitising the dog.     

Historic, pre-European settlement, and present-day contribution of wild ruminants to enteric methane emissions in the United States

The objectives of this analysis were to estimate historic (pre-European settlement) enteric CH(4) emissions from wild ruminants in the contiguous United States and compare these with present-day CH(4) emissions from farmed ruminants. The analysis included bison, elk (wapiti), and deer (white-tailed and mule). Wild ruminants such as moose, antelope (pronghorn), caribou, and mountain sheep and goat were not included in the analysis because their natural range is mostly outside the contiguous United States or because they have relatively small population sizes. Data for presettlement and present-day population sizes, animal BW, feed intake, and CH(4) emission factors were adopted from various sources. Present-day CH(4) emissions from livestock were from recent United States Environmental Protection Agency estimates. The most important factor determining CH(4) emissions from wild ruminants in the presettlement period was the size of the bison population. Overall, enteric CH(4) emissions from bison, elk, and deer in the presettlement period were about 86% (assuming bison population size of 50 million) of the current CH(4) emissions from farmed ruminants in the United States. Present-day CH(4) emissions from wild ruminants (bison, elk, and deer) were estimated at 0.28 Tg/yr, or 4.3% of the emissions from domestic ruminants. Due to its population size (estimated at 25 million), the white-tailed deer is the most significant present-day wild ruminant contributor to enteric CH(4) emissions in the contiguous United States.     

Isolation of Sarcocystis falcatula from the South American opossum (Didelphis albiventris) from Argentina.

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.     

Abortions caused by protozoa in agricultural animals]

A review is given on abortions in livestock caused by Toxoplasma gondii, Neospora caninum and Sarcocystis spp. Special emphasis is put on diagnostic procedures. T. gondii is considered to be a major cause of abortions in sheep and goats. Diagnosis is based on the characteristic lesions in the cotyledons, histologic and immunohistochemical examination, and on the detection of specific antibodies in body fluids or serum of aborted fetuses. Whether abortions in swine due to T. gondii are of practical importance is still unclear. The most important causative protozoal agent of abortions in cattle is Neospora caninum. This protozoon was found in 19 per cent of cattle fetuses submitted for examination in USA. Occasionally it was found also in aborted lambs, kids and foals. Diagnosis is based on the histologic or immunohistochemical detection of the parasite. Abortions can be regularly induced experimentally in large and small ruminants and in pigs by the oral inoculation of sporocysts of certain Sarcocystis species. However, under natural conditions abortion due to Sarcocystis was diagnosed only occasionally and only in cattle and sheep. The histologic examination of the fetus and fetal membranes is the only way to diagnose Sarcocystis abortion or neonatal infection at present.     

First isolation of Sarcocystis hominis from cattle in Japan.

Sarcocystis hominis was first isolated from slaughtered cattle raised in Japan. Cysts were 1,220-4,460 x 80-384 microns in size and their wall was 3 to 6 microns thick and appeared radially striated in the histopathological sections because of the presence of palisade-like villar protrusions on the surface. The protrusions were 3.1-4.3 x 0.7-1.1 microns in size and had many microtubules in the core. Two cynomolgus monkeys, Macaca fascicularis, fed with the Sarcocystis cysts began to pass sporocysts, which measured a size of 14.3-15 x 9.5-10 microns, in the feces 10 days after ingestion.     

Surveys on Coxiella burnetii infections in Swedish cattle,sheep, goats and moose

Background

Q fever is a zoonotic disease caused by the bacterium Coxiella burnetii. Prevalence data in ruminant species are important to support risk assessments regarding public and animal health. The aim was to investigate the presence of or exposure to C. burnetii in cattle, sheep, goats and moose, and to compare two enzyme-linked immunosorbent assays (ELISAs). National surveys of antibodies against C. burnetii were performed for dairy cattle (n=1537), dairy goats (n=58) and sheep (n=518). Bovine samples consisted of bulk milk, caprine of pooled milk, and ovine of pooled serum. Antibodies were investigated in moose samples (n=99) from three regions. A one-year regional cattle bulk milk survey was performed on the Isle of Gotland (n=119, four occasions). Cattle, sheep and goat samples were analysed with indirect ELISA and moose samples with complement fixation test. For the sheep, goat, and parts of the cattle survey, samples were run in parallel by ELISAs based on antigens from infected ruminants and ticks. Bulk milk samples from the regional cattle survey and vaginal swabs from a subset of the sheep herds (n=80) were analysed for the agent by polymerase chain reaction. Spatial clustering was investigated in the national cattle survey.

Results

The prevalence of antibodies in dairy herds was 8.2% with large regional differences. High risk clusters were identified in the southern regions. The prevalence among dairy herds on the Isle of Gotland varied from 55.9% to 64.6% and 46.4% to 58.9.0% for antibodies and agent, respectively, overall agreement between agent and antibodies was 85.2%. The prevalence of antibodies in sheep was 0.6%, the agent was not detected the vaginal swabs. Antibodies were not detected in goats or moose, although parts of the moose samples were collected in an area with high prevalence in cattle. The overall agreement between the two ELISAs was 90.4%.

Conclusions

The prevalence of antibodies against C. burnetii in dairy cattle in Sweden shows large regional differences. The results suggest that C. burnetii is a rare pathogen among Swedish moose, dairy goat and sheep. ELISAs based on ruminant and tick antigen performed in a similar manner under Swedish conditions.     

Frequency of Sarcocystis in pigs in Ohio and attempted transmission to cats and dogs.

Tissues of 236 sows, obtained at slaughter in Xenia, Ohio, were examined microscopically after trypsin digestion. Sarcocystis bradyzoites were found in eight of 236 (3.4%) pigs (in 8 diaphragms, 7 esophagi, and 1 heart) and in three of 101 tongues. After these infected porcine tissues were fed to three dogs and three cats, none of the animals shed Sarcocystis sporocysts in their feces.     

Sarcocystis infection in pigs of Hissar, Haryana, India and its transmission to dogs

Sarcocystis zoites were found in pepsin digests of 68.8% of 157 pigs from Hissar, Haryana. Sarcocystis-infected meat was fed to 4 young dogs and 2 cats. The dogs shed Sarcocystis sporocysts in their faeces 12 days after eating infected meat whereas cats did not shed sporocysts.     

The in vitro excystation of Sarcocystis gigantea sporocysts

Studies on the in vitro excystation of Sarcocystis gigantea sporocysts revealed that pretreatment before exposure to trypsin and bile was an essential prerequisite. However, in contrast to Sarcocystis tenella and Sarcocystis capracanis, incubation in cysteine hydrochloride under CO2 was largely unsuccessful for excysting Sarcocystis gigantea: of the pretreatments tested, only exposure to sodium hypochlorite proved effective. Excystation from sodium hypochlorite-pretreated S. gigantea sporocysts took place in trypsin and bile between temperatures of 30 and 43 degrees C and occurred rapidly at 39 degrees C. While the presence of bile or bile salts was essential for this process, that of trypsin was not, although more sporocysts excysted in its presence than in its absence. Excystation occurred in the presence of all bile types tested but not when Tween 80 was substituted for bile. The highest levels of excystation were recorded when cattle or sheep bile or sodium taurocholate were used and the lowest when chicken or pig bile were employed. Neither the concentration of sheep bile above 2.5%, nor hydrogen ion concentration (pH range 5.0-10.0) appeared to have any marked effect on the level of excystation obtained.     

Serologic responses of cats against experimental Sarcocystis neurona infections

Sarcocystis neurona is the most important cause of a neurologic disease of horses, equine protozoal myeloencephalitis (EPM). Cats and other carnivores can act as its intermediate hosts and horses are aberrant hosts. Little is known of the sero-epidemiology of S. neurona infections in cats. In the present study, antibodies to S. neurona were evaluated by the S. neurona agglutination test (SAT). Cats fed sporocysts from the feces of naturally infected opossums or inoculated intramuscularly with S. neurona merozoites developed high levels (> or =1:4000) of SAT antibodies. Antibodies to S. neurona were not found in a cat inoculated with merozoites of the closely related parasite, Sarcocystis falcatula. These results should be useful in studying sero-epidemiology of S. neurona infections in cats.     

Haematological and biochemical findings in bovine post-parturient haemoglobinuria and the accompanying Heinz-body anaemia

Sarcocysts morphologically similar to Sarcocystis muris were observed in the skeletal muscles of mice dosed with free isosporan sporocysts recovered from the faeces of naturally infected cats. Kittens fed these mice shed similar sporocysts measuring 8.7 ±0.1 x 10.8 ±0.1 μm in their faeces five to six days later. Feeding these sporocysts to mice and rats resulted in the formation of identical sarcocysts in mice, but not rats. Attempts to induce similar infections in mice using naturally acquired isolates of I. felis were unsuccessful.     

The prevalence and identity of Sarcocystis in beef cattle in New Zealand

Muscle tissue from the oesophagus and diaphragm of 500 beef cattle slaughtered in New Zealand was examined for Sarcocystis infection by microscopic examination of cysts isolated from muscle samples. All cattle were infected with Sarcocystis; based on light microscopy of cysts, 98% had thin-walled Sarcocystis cruzi cysts and 79.8% had thick-walled (Sarcocystis hirsuta/Sarcocystis hominis) cysts. Cysts were also collected for electron microscopy and transmission experiments. Thick-walled cysts could not be distinguished as S. hirsuta or S. hominis by light or electron microscopy. Thick-walled cysts were fed to three cats and one human volunteer; one cat shed sporocysts but not the human volunteer. Electron microscopy of the cysts revealed many features that have not been described previously.