Eosinophilic myositis resulted from Sarcocystis infection in prime marbled beef of Japanese black cattle

Partial changes of color (greenish to brownish) were found in prime marbled beef of Japanese black cattle. The disseminated lesions of the skeletal muscles were histopathologically examined in relation to Sarcocystis infection. The lesions in the muscles showed granulomas with inflammatory cell infiltration. The sarcocysts had a distinct wall, which was radically striated by palisading villar protrusions. The sarcocyst wall was surrounded by degenerative eosinophils and necrotic muscle fibers. In conclusion, eosinophilic myositis in prime marbled beef of Japanese black cattle resulted from Sarcocystis spp. infection. The muscular lesions were characterized by the presence of granulomas and capsulated sarcocysts surrounded by numerous eosinophils.


Introduction
Japanese black cattle were excised in the slaughter house in Matsuzaka-city and submitted to our Previous studies suggested that Sarcocystis spp., institutes.The specimens containing visible lesions often found in association with granulomatous were fixed in 10% neutral buffered formalin, myositis, should be responsible for eosinophilic processed by routine methods and embedded in myositis (Jensen et al., 1986;Gajadhar et al., 1986;paraffin wax. 4-µm paraffin sections were stained with Gajadhar and Marquardt, 1991;Wouda et al., 2006).hematoxylin and eosine (HE) and by van Gieson's and Eosinophilic myositis is a relatively rare disease in Weigert's staining.cattle observed in meat inspection after slaughter.

Sarcocystis infection in heart, esophagus, diaphragm
Macroscopic findings: The marbled beef had welland tongue of slaughtered cattle.Although the skeletal demarcated, oval or elongated greenish or grayishmuscles are the most often eaten parts of beef, the green lesions up to 2-10 mm in length and 2-8 mm in prevalence of Sarcocystis is relatively low in these diameter.The small disseminated lesions were a muscles.In addition, skeletal muscles are not severely typical form of eosinophilic myositis which resulted in affected by Sarcocystis.carcass condemnation (Figure I).The large-sized The prevalence of Sarcocystis spp.cysts was lesions were discrete focal stripes or patches.In some lower in Japanese beef (6.31%) than in beef imported portions, there was a rigid bulging of brownish lesions from America (36.78%) or Australia (29.49%) (Ono (Figure II). and Ohisumi, 1999).Marbled beef of Japanese black Histopathological findings: The lesions in the cattle is highly valued as brand-name beef produced in marbled muscles showed granulomas with the specified farms.
inflammatory cell infiltration.The granulomatous I found a partial change of color in prime beef of lesions had a central core consisting of degenerative Japanese black cattle.In this study, the disseminated eosinophilic leucocytes and remnants of necrotic lesions of the skeletal muscles were histopathoskeletal muscle fibers.Among the marbled muscle logically examined in relation to Sarcocystis infection.
fibers, there was accumulation of mixed inflammatory

Materials and Methods
cells, mainly eosinophils with some neutrophils, macrophages and plasma cells, as well as erythrocytes Samples of muscles from the hindquarters in (Figure III).Pale to neutral staining eosinophils were In the present study, histopathological examinations indicated that granuloma-associated observed around the sarcocysts with thick cyst wall.
sarcocysts were partially destroyed or enclosed by There was also diffuse eosinophil infiltration in the dense, organized accumulations of inflammatory connective tissue of normal skeletal muscles (Figure IV).cells.These results showed that the thick cyst walls in The sarcocysts had a distinct wall, which was the lesions were identical to those of Sarcocystis radically striated by palisading villar protrusions.The hirsute.The thick walled sarcocyst cannot be sarcocyst wall was surrounded by degenerative distinguished whether it is Sarcocystis hirsute or eosinophils and necrotic muscle fibers (Figure IV).
Sarcocystis hominis.However, Sarcocystis hominis Adjacent to the trapped sarcocyst, this cyst were has not yet been reported in Japan.enclosed with a thick outer rim of degenerative The pathogenesis of eosinophilic myositis is not hyalinized remnants of muscle fibers.
clear and this muscular lesion is not always found in Histopathological examinations revealed that cattle suffering from Sarcocystis spp.The incidence of eosinophilic miositis were closely associated with eosinophilic myositis is usually low in cattle (Wouda Sarcocystis infection.et al., 2006).This breed of cattle was mainly fed with Discussion concentrated fed.It is uncertain whether the cattle made some contact with carnivores as the definitive Muscle sarcocystosis is a parasitic infection host.The histopathological examinations showed 2 acquired by ingestion of sarcocysts of Sarcocystis spp.
kinds of morphological changes as follows: in feces from an infected carnivore.Sarcocystis spp.
granulomas with peripheral cell infiltration and have 2-host life cycle between carnivores and capsulated sarcocysts surrounded by degenerative herbivores.In this life cycle, cattle are known to serve eosinophils.The initial cellular response seemed to be as the intermediate host.In the previous study, the induced by substances (eosinophil chemoattractant) cows experimentally challenged with sporocysts released from the sarcocysts during their normal showed various clinical signs with myositis (Savini et metabolic process.These findings provided a al., 1996).Histopathologically, skeletal myositis was presumption that cattle with eosinophilic myositis associated with a mononuclear cell infiltration were predisposed to produce IgE in response to (primarily lymphocytes).Degenerating sarcocysts in Sarcocystis bradyzoite antigen, and that eosinophilic muscles elicited a mononuclear cell (mainly lymphocytic) response as early as 1 to 3 months after myositis represented an abnormal response to sarcocyst degeneration, including a host-dependent, infection.
Figure-I.Macroscopic photograph.Oval or elongated brownish lesions are seen in the marbled beef.Figure-II.Macroscopic photograph.A discrete large-sized lesion in the muscle.F i g u r e -I I I .M i c r o s c o p i c p h o t o g ra p h .Granuloma with inflammatory cell infiltration is seen.× 100, HE stain.Figure-IV.Microscopic photograph.Diffuse eosinophil infiltration seen in the connective tissue of normal skeletal muscles.× 150, HE stain.Figure-V.Microscopic photograph.The capsulated sarcocyst is surrounded by degenerative eosinophils and necrotic muscle fibers.× 150, HE stain.