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Abstract
Summary and conclusion
Sarcocystis species are widespread in cattle throughout the world, and some species are pathogenic and have medical importance.
In the present work, different species of Sarcocystis of cattle were studied in Assiut. Samples from the heart, oesophagus, diaphragm and ocular muscles were examined. In addition, blood samples were collected from 100 animal slaughtered in Assiut city abattoir.
Studies on Sarcocystis infection in cattle showed that the total infection rate was found to be 94% by light microscope examination and 98% serologically by enzyme linked immunosorbent assay ( ELISA ). Both macroscopic and microscopic Sarcocystis cysts were found in examined cattle.
The infection rate in different organs was 89% in ocular muscles, 84% in oesophageal muscles, 51% in heart muscles and 30% in diaphragmatic muscles.
Histological examination of infected muscles of cattle revealed the presence of two forms. The first one in the heart, oesophagus, diaphragm and ocular muscles possessed smooth and thin cyst wall. The second form recorded in ocular and oesophageal muscles only, it has a thick and radially striated cyst wall.
Ultrastructure studies of Sarcocystis species of cattle with transmission electron microscope revealed the presence of four species. The first one was Sarcocystis cruzi which characterized by thin wall with hair like villar protrusions folded over the surface
of the cyst and approximatly parallel to the cyst surface. Host
mitochondria seen near the parasitophorous vacuolar membrane of villar protrusions. The second species was Sarcocystis hirsuta that provided with club or bulb like villar protrusions with
tapered tips. Some of villar tips folded to form conical projections. The third species was Sarcocystis hominis with cylindrical (finger like) villar protrusions perpendicular on the cyst surface with broad tips. The fourth species was Sarcocystis fusiformis like cyst which has highly branched villar protrusions with constricted base. This is the first time of discription of this species in cattle.
Experimental infection of dogs and cats with Sarcocystis of cattle revealed that only the dogs complete the cycle of Sarcocystis cruzi. The dogs began to shed sporocysts in their faeces from seven days post inoculation. The sporocysts were low in number untill 30 days post inoculation, then the sporocysts increased in number and continuously passed till the end of experiment (60 days post inoculation ). The sporocysts measured 15.73 × 10.01µm.
Prevalence of infection with different species of Sarcocystis was high in examined cattle in Assiut city, the infection rate was 98%. This result may be due to direct contact of cattle with dogs and cats which leads to contamination of their food with oocysts of different species of Sarcocystis.
Sarcocystis cysts were detected in different examined organs, but highest infection rate was detected in ocular muscles (89%). Ocular muscles may play a role in dissemination of Sarcocystis infection in carnivorous, where it considered as unedible parts for human consumption.
Serological examination by ELISA confirms the microscopical examination and it is more accurate in diagnosis of Sarcocystosis.
The present work revealed sporadic cases of local myositis, three cases were detected in diaphragm, oesophagus and ocular muscles as a result of Sarcocystis infection.
Transmission electron microscopic examination was used for identification of different species of Sarcocystis, where the cyst wall and morphological characters of villar protrusions are the main criteria for differentiation between species. Four species were detected in the present work.
It is first time for detection of Sarcocystis fusiformis like cyst in cattle, but further studies are recommended to find out their life cycle.