The Prevalence Investigation And The Ultrastructure Study Of Sarcocystis

[Objectives] To investigate the prevalence of the Sarcocystis in pigs and human muscles in Yunnan Province. To study the ultrastructure of the sarcocyst from pigs, and the influence of preserving pork samples by freezing on the sarcocyst ultrastructure. To explore whether we can preserve samples by freezing to further identify the Sarcocystis.[Methods] A muscule compress method was used to examine the pork samples and muscle samples of human autopsy. The sarcocysts of Sarcocystis suihominis was isolated from the muscle samples on the day of collecting the samples, 3 days and 30 days after preservation by freezing at -20# respectively and isolated sarcocysts of Sarcocystis miescheriana from the muscle samples on the day of collecting and 20 days after freezing preservation respectively. Then the ultrastructure of the two kind of sarcocysts was observed by transmission electron microscope.[Results] The sarcocysts were found in 78 of 127 (61.4 %) of pigs in Eryuan county Dali and the prevalence of S.swhominis(6\A%) was remarkably higher than that of S.miescheriana (1.6%). However, the Sarcocystis prevalence of pigs in Kunming City was 43.2%(64/148),and the prevalence of S.suihominis (10.8%) was remarkably lower than that of S.miescheriana (32.4%)(P<0.001). The total prevalence of pigs in Eryuan county Dali was higher than that in Kunming, The 17 human body autopsy muscle samples examined were all negativeThe cyst wall of S.suihominis had hairlike villar protrusions. There were slight waves at the base of the protrusions , the villar protrusions had many microtubules extending from their tips to the ground substance(GS), the GS was approximately 0.36 microm thick. S.miescheriana sarcocyst wall had fingerlike protrusions of which the size varies greatly, there were bulblike inpocketings at the base or among the protrusions The tips of the protrusions were flat or blunt. There were small number microtubules in the middle of the protrusions, the cyst wall of the two Sarcocystis were still clear after freezing. There was no obvious change in the length, width of2001the protrusions and the thickness of the ground substance after freezing(P>0.05). But the structure of the bradyzoite in the sarcocysts was dim and even dissolved. These changes were more significant as the time gone on.[Conclusions] The major species of the Sarcocystis in the infective pigs in Eryuan county Dali and in Kunming is S.suihominis and S.miescheriana respectively. The Sarcocystis prevalence of pigs in Eryuan county Dali is significantly higher than that in Kunming. Compared with the past, there is no obvious change in the Sarcocystis prevalence of pigs in Eryuan county Dali but that in Kunming is much lower. The Sarcocystis infection in human muscles in Yunnan had not been found this time. The cyst wall of S.suihominis and S.miescheriana each has its unique ultrastructure characteristics which can be used as an effective means to identify the species of the Sarcocystis. Preserving the muscle samples by freezing has no influence on identifying the species and the ultrastructure of the sarcocysts wall is preserved well in a certain time.