牛肉孢子虫病研究：流行病学调查与病原种类研究

本文报告1986——1988年对贵州省五地区十个县(市)耕牛肉孢子虫病调查,共剖检水牛155头和黄牛195头。调查肉孢子虫感染情况;对几种住肉孢子虫进行形态观察、测量大小和动物感染试验。结果表明:贵州耕牛住肉孢子虫共有三种,总感染率为89.4%。寄生于水牛的住肉孢子虫有两种,Ⅰ、梭形住肉孢子虫 sarcocystisfusiformis,感染率100%,终宿主为猫,Ⅱ、小型住肉孢子虫 sarcocystis sp,感染率83.9%(与梭形住肉孢子虫混合感染);终宿主为狗。Ⅲ、黄牛一种;枯氏住肉孢子虫 sarcocystis cruzi,感染率81%,终宿主为狗。三种住肉孢子虫以梭形住肉孢子虫感染最严重。患牛全身布满包囊,病变明显而销毁和高温处理的占3.9%。各种感染程度分别为:轻度占62%,中度占24%,严重占14%。包囊在牛体内的分布以食道最多,为100%,颈肌次之,为73.5%,舌肌和背肌均为40%,心肌未见有此种包囊。三种住肉孢子虫以梭形住肉孢子虫的包囊最大,平均9×3.5毫米,孢子囊较小,平均13.4×7.8微米,慢殖子平均14.4×5.5微米。小型住肉孢子虫和枯氏住肉孢子虫两者相似,包囊细小,大小分别为1.6×0.17毫米和2×0.16毫米.慢殖子大小为13.8×6.7微米和13.87×4.93微米,孢子囊大小为15.81×10.33微米和15.75×10.22微米。猫感染梭形住肉孢子虫排囊前期6—7天,排囊持续2—22天,狗感染小型住肉孢子虫排囊前期为8天,持续1—20天;狗感染枯氏住肉孢子虫排囊前期为10天,持续1—10天。兔感染各种住肉孢子虫均未获得成功。对本病的防治方法文内提出讨论建议。     

水牛枯氏住肉孢子虫在水牛与黄牛体内的发育史

11头5～8月龄公水牛犊和2头7日龄黑白花奶牛犊,分别人工感染80～2000万个水牛源枯氏住肉孢子虫孢子囊,2头同龄公水牛犊不感染作对照。感染后12、22和32天在大、中、小血管和毛细血管内出现第一代裂殖体,32.86×16.43(19.08～46.64×12.72～21.2)μm,含100～450个裂殖子;32～46天在毛细血管和小血管内发现大量的第二代裂殖体,18.21×9.87(10.60～29.68×6.36～13.78)μm,含30～110个裂殖子;28～40天,第二代裂殖子出现于血液中或单核细胞内;46天初级幼包囊形成,78天部分包囊成熟,98天(黄牛)包囊成熟。     

中国水牛两种住肉孢子虫包囊超微结构的比较研究

本文对采自我国湖南水牛食道肌的大、小两种住肉孢子虫包囊的超微结构进行了研究。两种包囊的细胞(母细胞和缓殖子)未发现有明显的结构区别,而包囊壁的结构则揭示出明显的差异。大包囊的原囊壁向表面皱褶形成菜椰花样的突起,突起内含纤丝,突起表面有凹陷;而小包囊的原囊壁皱褶形成长指形的突起,突起内不含纤丝,倒伏在包囊表面,突起壁是平滑的,无凹陷。这一观察表细:我国水牛体内的大包囊属于梭形住肉孢子虫,小包囊可能是枯氏住肉孢子虫。     

水牛梭形住肉孢子虫抗原的制备及反应原性研究

将制备的水牛梭形住肉孢子虫包囊抗原及缓殖子抗原，应用血清学试验鉴定了其反应原性。结果表明，水牛梭形住肉孢子虫包囊抗原，缓殖子抗原与自然感染病牛剖检的阳性吻合率分别为５６％和７１％；水牛梭形住肉孢子虫与黄牛枯氏住肉孢子虫之间有共同抗原成份。     

住肉孢子虫组织石蜡切片过氧化物酶染色检测水牛住肉孢子虫病抗体的研究

本文报告采取自然感染梭形住肉孢子虫包囊的水牛肌肉组织石蜡切片抗原,应用辣根过氧化物酶标记抗体,间接染色法,检测来自我省湘北、湘中地区的75头水牛及5头黄牛血清中的住肉孢子虫抗体,其检出率分别为94.66%和80%。结果表明IIP法对病牛血清中特异性抗体的检出有较高的敏感性和特异性。     

水牛枯氏住肉孢子虫病

水牛枯氏住肉孢子虫病是近年来新发现的一种寄生虫病、该病不但危害水牛的健康，而且严重影响其肉品卫生。湖南省畜牧兽医研究所与北京农业大学等单位合作对该病进行了较详尽的研究。一、病原枯氏住肉孢子虫Sarcocystiscruzi（Hasselman－n1923，Wenyenl926）属泡子虫纲Sporozoasida，真球虫目Eucoccidiorida发美尔亚目Eimerioria，住肉抱子虫科Sarcocystjda，住肉泡子虫属Sarcocystis。最初Ha。elmannl923年发现于黄牛心肌中，命名为Mieshc。riacruzj。过去人们长期把它看作是梭形住肉泡子虫已fusiformis（水牛一猫住肉泡子虫）的同物…     

牛和羊心肌住肉孢子虫包囊病理组织学及分型

运用石蜡切片HE染色和PCR技术,调查分析牛和羊心肌(黄牛405份,绵羊311份)食源性住肉孢子虫病的流行情况和感染强度。结果发现,黄牛住肉孢子虫感染率为49.38%(200/405,95%CI=44.54~54.23),感染密度为5.17~8.73个/cm2,绵羊住肉孢子虫的感染率为32.48%(101/311,95%CI=27.51~37.87),感染密度为7.06~32.02个/cm2。其中黄牛住肉孢子虫薄壁包囊占88.00%,厚壁包囊2.00%,混合感染10.00%,而绵羊住肉孢子虫薄壁包囊、厚壁包囊、混合感染的感染率分别为38.61%,31.68%,29.71%。牛、羊心肌消化液成功扩增出DNA长度为350bp的牛住肉孢子虫基因片段、羊住肉孢子虫600bp的基因片段,进而验证形态学结果。病理组织学观察和PCR结果显示,牛和羊心肌中分别存在住肉孢子虫S.cruzi、S.hominis和S.arieticanis、S.tenella,均对牛羊存在致病性,并且危害肉品质量安全。该研究为防控牛羊住肉孢子虫病,牛、羊肉品的安全监测提供参考依据。为中原地区牛、羊心肌住肉孢子虫病流行情况的首次报道。     

水牛住肉孢子虫病的研究进展

本文综述了国内外关于水牛住肉孢子虫病的病原、生活史、流行病学、临床与病理学、免疫诊断、肉品卫生及防治等方面的研究成果。详细论述了新证实的水牛枯氏住肉孢子虫及另外两种住肉孢子虫的形态学、发育史、致病性等生物学特性和水牛住肉孢子虫病的临床与病理学,五种检测抗原和抗体的免疫学诊断技术与药物防治方法。     

牦牛的住肉孢子虫两新种宿主范围的研究

对牦牛的两新种住肉孢子虫进行了宿主范围的研究,其结果是:耗牛住肉孢子虫(S.Poephagi sp nov.),用20只无卵囊的健康幼犬,10只无卵囊的健康幼猫,分别口服感染其包囊4000条/只,感染后每天连续进行粪便检查,幼犬未见有印囊或孢子囊排出,幼猫感染后第7～10天开始排出孢子囊,排出持续期为8～12天,平均每克粪便内有43.6(11～71)个,孢子囊呈圆形或卵圆形,无色透明,大小为13.68×9.39(9～15.8×7～13.2)μm,牦牛住肉孢子虫是猫源性虫体,犬不能作为终未宿主。牦牛犬住肉孢子虫(S.Poephagicanis sp.nov.),用20只无卵囊的健康幼犬和10只幼猫,分别人工感染其包囊4000条/只,感染后连续检查粪便,幼犬在感染后第7～20天开始排出孢子囊,大多数是在第7～9天排出,持续期为13～26天,每克粪便内平均排出孢子囊203(15～286)个,孢子囊呈椭圆形,两端较钝,大小为14.63×10.63(10.5～18.5×7～14.25)μm,有两层囊壁,外膜光滑,该种为犬源性虫体,猫不能作为终末宿主。大白鼠、小白鼠、豚鼠、家兔和小鸡分别口服感染两种住肉孢子虫包囊,感染后经粪便检查,均未发现有孢子囊,上述实验动物各口服从幼猫粪便获取的牦牛住肉孢子虫孢子囊,或从幼犬粪便获取的牦牛犬住肉孢子虫孢子囊,90天后剖检,肌肉内均无包囊存在,证明这些动物均不能作其宿主动物。     

肉孢子虫包囊简易直接检查法

据Heydorn等报道:寄生于牛的肉孢子虫有枯氏住肉孢子虫、人住肉孢子虫、猫住肉孢子虫三种,三种在包囊的形态学上有所差异。齐藤守弘等设计了肉孢子虫包囊简易直接检查法,并与以前的胰蛋白酶消化法进行了比较:用这两种方法检查肉孢子虫,检出率几乎无差异。但是,用     

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.     

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.     

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.     

Prevalence and distribution patterns of <Emphasis Type="Italic">Sarcocystis</Emphasis> spp. in buffaloes in Beni-Suef,Egypt

This study was performed for the purpose of investigating the prevalence of Sarcocystis spp. in buffaloes in Beni-Suef Governorate, Egypt. Both macroscopic (Sarcocystis fusiformis) and microscopic (Sarcocystis levinei) cysts were recognized, and were differentiated by their morphological features and location in the tissues. Of 379 buffaloes examined in abattoirs in Beni-Suef, 299 were found to be infected, with an overall prevalence of 78.9%. Depending on age, three categorized groups of naturally infected buffaloes were examined: male buffalo calves aged 1.5–2 years, adult females aged 2–5 years, and females older than 5 years. Among these groups, infection rates were 74.5%, 82.3%, and 81.2%, respectively. Organs examined included esophagus, tongue, and heart. Macroscopic cysts were examined by the naked eye through meat inspection in abattoirs, while the pepsin-digestion method and the histological technique were applied to detect microscopic cysts. It has been found that esophagus showed the highest rate of infection among the infected organs, with both macroscopic and microscopic cysts seen in the infected buffaloes. Moreover, results of the pepsin-digestion method proved more accurate than those produced by the histological technique in terms of infection rates for the microscopic cysts. Our findings indicated that infected buffaloes aged 2–5 years showed the highest mixed infection rate (82.3%) for both types of cysts. The high prevalence of microscopic Sarcocystis spp. in Beni-Suef Governorate reflects a significant role played by stray dogs, rather than cats, in the transmission of these parasites.     

Coyote as a final host for Sarcocystis species of goats, sheep, cattle, elk, bison, and moose in Montana

Tissues (1 kg) from sheep, goats, cattle, moose, bison, or elk naturally infected with Sarcocystis species were fed to one to four Sarcocystis-free coyotes and the number of sporocysts in feces and intestines were counted. All 12 coyotes fed naturally infected tissues shed Sarcocystis in feces, with a prepatent period of 9 to 15 days. The four coyotes fed infected beef had 15, 25, 113, and 201 million sporocysts in their feces and intestines. The coyotes fed elk, moose, or bison had 2.5, 15, and 2.5 million sporocysts in their intestines, respectively. Sporocysts in feces of coyotes fed musculature of cattle, sheep, goats, and elk were structurally similar to those described previously from the feces of dogs. This is evidently the first report of the completion of life cycle of Sarcocystis species in moose and bison. Cross-transmission experiments indicated that one species of goat Sarcocystis completes its life cycle in both dog and coyote and that the ovine Sarcocystis is not transmissible to goats.     

Prevalence of Sarcocystis spp. in meat-producing animals in Iraq.

The prevalence of Sarcocystis spp. infection was investigated in 605 sheep, 826 goats, 1080 cattle, 580 water buffaloes and 36 camels slaughtered from 1992 to 1996 in the Baghdad area (Iraq) using naked eye examination for macroscopic sarcocysts, and peptic digestion, muscle squash, squeezing methods and indirect fluorescent antibody test (IFAT) for microscopic types. The intestinal stages of the parasite were also studied in dogs experimentally fed with tissues containing microscopic cysts. The percentage prevalence of macroscopic cysts were 4.1, 33.6, 0.2, 15.6 and 0, and of the microscopic type, 97.0, 97.4, 97.8, 82.9 and 91.6 for the above-mentioned hosts, respectively. Among the different organs examined, macroscopic cysts were found to be highest in the oesophagus and the lowest in the heart. Peptic digestion method gave the highest rate (93.3%) followed by indirect fluorescent antibody test (IFAT) (88.6%), squeezing (81.3%), and muscle squash (81.2%). Each infected dog shed a total of about 150-200 million sporocysts. Histologically, developmental stages of the parasite were detected in the small intestinal mucosa of the dogs on Days 7 and 13 post-infection.     

Host resistance and faecal sporocyst excretion in dogs exposed to repeated infection with Sarcocystis levinei

A marked reduction in the faecal excretion of sporocysts was observed in experimental pups, following the repeated oral administration to them of buffalo cardiac muscle infected with Sarcocystis levinei. Sporocysts excreted from days 9 to 25 post-infection (pi) exhibited a gradual reduction in the quantum. Maximum intensity of excretion of sporocysts was recorded between days 9 and 16 pi, becoming moderate after day 16, light after day 21 and completely absent after day 36. After the subsequent feeding to pups of S. levinei infected buffalo cardiac tissues at 40 day intervals the quantity of sporocysts shed was less, the prepatent period was prolonged and the patent period was considerably shortened. The peak period of excretion varied depending upon the number of exposures of the pups to the infected S. levinei tissues from buffaloes (Bubalus bubalis).     

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.     

Prevalence,biology, and distribution pattern of Sarcocystis infection in water buffalo (Bubalus bubalis) in Iran

This study was conducted to determine the prevalence, distribution pattern, and the Sarcocystis species involved in slaughtered water buffaloes (Bubalus bubalis) in the Khuzestan, Iran by macroscopic and histological examination. The esophagus, heart, diaphragm, tongue, masseter, and thigh muscles were investigated. Esophagus and thigh muscles of only 3 of the 100 examined water buffaloes (3%) were infected with macroscopic Sarcocystis, whereas at microscopic level Sarcocystis were found in 83 of the 100 examined animals (83%). The highest prevalence rate of microscopic cysts was found in masseter muscle (57.1%) and then followed by tongue, diaphragm, esophagus, heart, and finally, thigh muscles (30.0%). There was no significant difference between males (83.6%) and females (82.0%) or between two investigated age groups (≤2 years old, 78% versus >2 years old, 88%). Based on the size of the sarcocysts, thickness of the walls and location of the cysts, Sarcocystis buffalonis as a macroscopic form and Sarcocystis levinei and Sarcocystis dubeyi as the microscopic forms were diagnosed in the examined muscles of the buffaloes of this area. Sarcocystis fusiformis was not seen in the examined organs of these buffaloes. The high prevalence rate of microscopic Sarcocystis in this region indicates that dogs have a more significant role than cats in transmission of these protozoa.     

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.