河南省奶牛安氏隐孢子虫感染的流行病学调查

为了解河南省奶牛安氏隐孢子虫病流行情况,采用饱和蔗糖溶液漂浮法和改良抗酸染色法对河南省12个规模化奶牛场和7个奶牛养殖小区共计2 268份粪便样本进行检查,发现109份为阳性粪便样本,感染率为4.8%。卵囊呈长椭圆形,平均大小为7.8μm×6.4μm,卵囊指数为1.22;12个养殖场中10个为阳性场,7个养殖小区中4个为阳性小区,不同地区奶牛安氏隐孢子虫感染率统计学差异显著(P0.05);不同年龄段奶牛安氏隐孢子虫感染率统计学差异极显著(P0.01);不同养殖方式奶牛隐孢子虫感染率统计学差异不显著(P0.05)。结果表明:奶牛隐孢子虫感染流行范围较广,存在一定人兽共患风险。     

河南省部分地区乳牛隐孢子虫病的流行病学调查

为进一步掌握乳牛隐孢子虫病在河南省的流行动态,从河南省郑州、开封、济源和鹤壁4个地区9个奶牛场采集12月龄以内的乳牛粪便样品582份,用饱和蔗糖溶液漂浮法和改良抗酸染色法进行检测。结果显示,隐孢子虫总感染率为26．12％（152／582）。其中,断乳前犊牛（5日龄至2月龄）隐孢子虫感染率为30．91％（51／165）,断乳后犊牛（3～12月龄）感染率为24．22％（101／417）。依据形态数值初步鉴定为2种隐孢子虫,即微小隐孢子虫和安氏隐孢子虫。微小隐孢子虫在断乳前犊牛阳性样品中的比率为50．98％（26／51）,在断乳后乳牛阳性样品中的比率为9．90％（10／101）。另外,饲养方式（断乳前犊牛单独隔离饲养和未隔离饲养）对断乳前犊牛2种隐孢子虫的感染率有显著影响。     

河南省绵羊隐孢子虫病的流行病学调查

为获得河南省绵羊隐孢子虫的流行病学资料,应用饱和蔗糖溶液漂浮法和改良抗酸染色法对河南省4个地区的5个羊场共1701份绵羊粪样进行了检测,并对绵羊隐孢子虫感染的风险因素进行了评估。结果表明,查出隐孢子虫阳性样品80份,总阳性率为4．70％,3周龄羔羊和产后3周母羊的感染率最高,分别为41.18%和6．29％。根据隐孢子虫卵囊的形态学数值分析结果,将发现于绵羊的隐孢子虫卵囊初步鉴定为微小隐孢子虫和安氏隐孢子虫。同时发现绵羊隐孢子虫感染存在年龄差异,但未见明显的季节性变化。     

河北省奶牛场犊牛安氏隐孢子虫的分离鉴定

本研究从河北省奶牛场有腹泻症状2月龄左右的犊牛粪便中分离卵囊,进行病原分离与虫株鉴定。采集腹泻犊牛的新鲜粪便24份,采用饱和蔗糖溶液漂浮法和抗酸染色法检测隐孢子虫卵囊,观察卵囊形态、大小。提取卵囊基因组DNA,进行18S rRNA基因PCR扩增及琼脂糖凝胶电泳检测。对扩增片段进行序列测定及分析,进一步确定分离虫株隐孢子虫的种类/基因型,根据18S rRNA基因核苷酸序列构建系统发育进化树,确定虫株亲缘关系。结果显示,5份样品检出隐孢子虫卵囊,感染率为20.83%。形态学观察卵囊呈长圆形或椭圆形,大小为(5.0～8.2)μm×(4.2～6.3)μm,平均大小为6.6μm×5.3μm,卵囊指数为1.24,鉴定分离虫株为安氏隐孢子虫。PCR扩增出预期大小为1 188 bp的特异性片段,序列分析和同源性分析结果表明,分离株与安氏隐孢子虫AB089285.2株、AB513856.1株、AY954885.1株的同源性为98.7%～98.8%,进一步表明分离的隐孢子虫虫株为安氏隐孢子虫。在种系进化关系上,分离株与安氏隐孢子虫AB513856.1株亲缘关系最近。本研究为揭示河北省奶牛隐孢子虫病的流行特征,实施有效防制措施提供了科学依据。     

湖南省牛的隐孢子虫病调查及小鼠感染试验

对湖南省８个县（市）的２９６头奶牛、１７７头水牛及１２头黄牛进行了隐孢子虫病的调查。发现６个县（市）的牛有隐孢子虫的感染。奶牛感染率为５．３％～２８．８％，其中某牧场１岁以下犊牛的感染率（４６．７％）高于１岁以上牛（２３．９％），３、４月龄犊牛的感染率（分别为１００％和６０％）高于４月龄以上的犊牛；水牛感染率６．６％～４０％；黄牛中未发现隐孢子虫感染。以牛粪中分离出的隐孢子虫卵囊人工感染小鼠成功，     

隐孢子虫卵囊部分特性研究

本试验对小球隐孢子虫卵囊、鼠隐孢子虫卵囊以及新发现的隐孢子虫亚型卵囊的抗酸染色特性进行了观察，发现只有小球隐孢子虫卵囊具有酸染色特性。     

奶牛源微小隐孢子虫的分子鉴定及动物感染试验

采用饱和蔗糖溶液漂浮法检查商丘市某奶牛场牛新鲜粪便样本的隐孢子虫卵囊,用18SrRNA基因对隐孢子虫进行PCR扩增和限制性片段长度多态性分析;基于GP60基因位点对微小隐孢子虫进行基因亚型鉴定。结果显示:103份样本中有50份为隐孢子虫阳性,42份经形态学鉴定为安氏隐孢子虫,8份形态学未能鉴定到种。经限制性片段长度多态性分析,7个分离株为微小隐孢子虫,1个分离株为牛隐孢子虫;序列比对分析,7个微小隐孢子虫均为人兽共患基因亚型IIdA19G1。接种1头3日龄犊牛1×106个卵囊,潜隐期为3d,显露期为14d,于感染后第7天和第10天出现2个排卵囊高峰期,收集到大量纯卵囊。     

合肥市犬隐孢子虫感染情况初步调查

目的了解合肥市犬隐孢子虫的感染情况。方法在合肥市随机采集不同年龄、性别与饲养条件的犬粪样69份,采用金胺-酚改良抗酸染色法检测粪样隐孢子虫感染情况,并根据卵囊大小和形态,进行虫种鉴定。结果犬隐孢子虫感染率为28.99%。对68个隐孢子虫卵囊进行观察和测量,椭圆形卵囊大小平均为6.20μm×4.34μm,卵囊形状指数平均为1.44,初步鉴定为鼠隐孢子虫（Cryptosporidium muris）;近圆形卵囊,大小平均为4.69μm×4.58μm,卵囊形状指数平均为1.125,初步鉴定为微小隐孢子虫（Cryptosporidium parvum）。结论犬隐孢子虫的感染率存在年龄差异,年龄越小,感染率越高;饲养管理条件差的犬隐孢子虫感染率高;而隐孢子虫感染率与性别没有关系。     

广东省乳牛隐孢子虫病的流行病学调查

对广东省10个奶牛场进行了隐孢子虫病的流行病学调查，并按大致10％的采样率采集了1087头乳牛的新鲜粪便，以饱和蔗糖漂浮法和改良抗酸染色法检查隐孢子虫卵囊，其中检出卵囊的阳性牛92头，阳性率为8．46％；有7个场检出隐孢子虫卵囊，场阳性率为70％。这7个奶牛场的卵囊阳性检出率分别是10．00％、7．19％、6．67％、9．80％、6．72％、12．76％和6．72％。调查发现，乳牛隐孢子虫的阳性率和感染强度与乳牛年龄呈负相关关系，而且可能与气候有关；所检出的隐孢子虫卵囊经形态学鉴定为鼠隐孢子虫(Crptosporidium muris)。     

河南省鸵鸟隐孢子虫流行病学调查

为了系统掌握河南地区鸵鸟隐孢子虫流行状况,于2006年8月～2007年8月对河南地区6个养殖场共829份样品应用饱和蔗糖溶液漂浮法和改良抗酸染色法进行感染情况调查,结果显示隐孢子虫总感染率为1.7%(14/829),其中,郑州某驼鸟场的感染率2.8%(14/506),其他养殖场未发现隐孢子虫感染.所查到的14份隐孢子虫阳性样品来自20～40日龄鸵鸟,表明幼龄鸵鸟更容易感染隐孢子虫.鸵鸟隐孢子虫卵囊大小为4.2～6.0 μm×4.5～5.0 μm,平均5.56 μm×4.48 μm,卵囊形状指数(L/W )为1.24(n=100),根据卵囊形态结构特征初步鉴定为贝氏隐孢子虫(Cryptosporidium baileyi).     

Cryptosporidium infection in juvenile pet rabbits

Cryptosporidium infection was confirmed by fecal examination for the first time in pet rabbits in a wholesale store located in Kanagawa Prefecture, Japan. Fecal samples were obtained postmortem from juvenile rabbits (n=66), which had died after developing diarrhea. Feces from healthy rabbits (n=30) were also collected and examined as controls. Two types of Cryptosporidium oocysts distinctive in size and shape were found (Type A and B). Types A and B oocysts were detected from 16.7% and 13.6% of the diarrheic, and 3.3% and 0% of the normal feces, respectively. Since Cryptosporidium oocysts were detected at a higher rate in the diarrheic rabbits than in the healthy rabbits, special caution should be taken when handling a pet rabbit presenting with diarrhea.     

Cryptosporidium infection in non-human hosts in Malawi

Of 1346 faecal samples from the Chikwawa and Thyolo districts of Malawi, analysed for the presence of Cryptosporidium oocysts between October 2001 and May 2003, 61.3% were from cattle (29.8% of these were from calves <6 months old). Cryptosporidium oocysts were detected during all three seasons studied in Chikwawa and Thyolo. In Chikwawa, 13.6% of adult cattle and 11.7% of calves were infected, compared to 28.9% of adult cattle and 36.7% of calves in Thyolo. Dependent on season, between 7.8% and 37.7% (Chikwawa) and 16.7% and 39.3% (Thyolo) of cattle samples contained oocysts. In Chikwawa, the highest percentage of infections occurred in the cool season, whereas in Thyolo, the highest percentage of infections occurred in the dry season. Faecal samples from goats [n=225], pigs [n=92], sheep [n=6]), rabbits, guinea pigs, chickens, ducks, turkeys, doves and guinea fowls were also analysed. Up to 5.6% of goat samples contained oocysts in Chikwawa, compared to between 16.7% and 39.3% in Thyolo. Again, in Chikwawa, the highest percentage of infections occurred in the cool season and the lowest in the rainy season, whereas, in Thyolo, the highest percentage of infections occurred in the dry season and the lowest in the cool season. In pigs, more infections were detected in the dry season in Chikwawa, but infections in the cool season were similar (17.7%), whereas in Thyolo, infections occurred in all three seasons (17.9% in the rainy season, 25% in the cool season and 60% in the dry season). Of ten diarrhoeic, oocyst positive cattle faecal samples collected from Chikwawa and subjected to PCR-RFLP, four oocyst positive samples (two from heifers, one from a cow and one unknown) were amplified at an 18S rRNA and Cryptosporidium oocyst wall protein (COWP) loci. RFLP of the 18S rRNA locus indicated that Cryptosporidium parvum, Cryptosporidium hominis, Cryptosporidium bovis and/or Cryptosporidium ryanae DNA, or a mixture of them was present. Cryptosporidium parvum DNA was identified in one sample that amplified at the COWP locus, indicating the presence of the major zoonotic Cryptosporidium species in Malawi.     

Host responses to Cryptosporidium infection

Cryptosporidium is a clinically and economically important infection whose pathogenic effect begins with colonization of the intestinal epithelium. Despite intensive efforts, a consistently effective therapy for the infection has yet to be identified. Morbidity and mortality results from ongoing loss of absorptive epithelium, which leads to villous atrophy and malabsorption and release of inflammatory mediators that stimulate electrolyte secretion and diarrhea. With further clarification of the mechanisms underlying enterocyte malfunction in Cryptosporidium infection, it should be possible to design rational nutritional and pharmacologic therapies to enhance nutrient and water absorption, promote the clearance of infected enterocytes, and restore normal villus architecture and mucosal barrier function.     

Prevalence of Cryptosporidium infection in calves in France

Two multicentre surveys were conducted in France to estimate the prevalence of Cryptosporidium infection in calves using qualitative ELISA for detection of Cryptosporidium coproantigens and oocysts. The first survey involved 4-12-day-old calves in six dairy-calf distribution centres, collecting calves from seven Administrative Regions (Aquitaine, Bretagne, Franche-Comté, Lorraine, Normandie, Nord, Pays de Loire). For each region, 20 calves were selected every month for 12 consecutive months (October 1995-September 1996). Prevalence of Cryptosporidium infection was 17.9% (Confidence Intervals (C.I.) 95%=[16.1%; 19.8%]) among the 1628 selected calves, of which only 5.3% had diarrhoea. The second survey conducted between November 1995 and May 1996 involved 4-21-day-old calves examined by veterinary practitioners who selected 189 livestock farms of dairy- or suckler-type in ten Administrative Departments (Allier, Cantal, Creuse, Doubs, Ille-et-Vilaine, Maine-et-Loire, Manche, Pas-de-Calais, Sa?ne-et-Loire, Vendée). Cryptosporidia were detected in 105 (55.6%) of the farms. Among the 440 calves examined, of which 398 (90.5%) presented diarrhoea, cryptosporidia were found in 191 animals, i.e. a prevalence of 43.4% (C.I. 95%=[38. 8%; 48.0%]). Breed of calves and type of housing had very little impact on prevalence in this survey. Some regional variations could be noticed, even if cryptosporidia infection is widespread. Monthly variations could be related to seasonal peaks in calving with a lower infection rate during summer.     

Cryptosporidium infection in dogs in Osaka,Japan

Cryptosporidium parvum is a zoonotic pathogen composed of genetically distinct but morphologically identical genotypes. Recent molecular study indicates that dogs may transmit the cattle genotype, which is known to be pathogenic to humans. Although large-scale studies of Cryptosporidium infection in dogs have been performed in several countries, the isolates were not accurately identified because of the lack of a method for molecular analysis. It is important to identify the isolates harbored in dogs, which come in close contact with humans, in order to control human cryptosporidiosis. The aim of the present study was to calculate the prevalence of Cryptosporidium infection in dogs in Osaka city, Japan, and to characterize the isolates molecularly. The prevalence was determined to be 9.3% (13/140) by PCR. All isolates were found to be Cryptosporidium canis (previously known as the dog genotype), which is thought to be non-pathogenic in humans, based on the sequencing of diagnostic fragments. These results indicate that PCR-based diagnostic methods are a useful tool for the diagnosis and molecular epidemiology of Cryptosporidium infection in dogs, and that dogs living in Osaka are not a significant reservoir for human cryptosporidiosis. It is unclear why C. canis is dominant in dogs. Further study is required to understand this partial parasitism.     

河南省山羊隐孢子虫流行病学调查

对河南省4个山羊场进行了隐孢子虫病流行病学调查.采集山羊粪样1 017份,以饱和蔗糖漂浮法和改良抗酸染色法检查,结果共检出隐孢子虫卵囊阳性山羊粪样28份,平均感染率为2.75%;有2个山羊场检出隐孢子虫卵囊,场感染率为50%;中牟某羊场阳性率最高,达4.95%;在各年龄段中,2～4月龄山羊隐孢子虫感染率最高,达5.43%;山羊隐孢子虫感染可能与季节有关;所检出的隐孢子虫卵囊经形态学观察,初步鉴定为微小隐孢子虫(Cryptosporidium parvum).     

Morphological and molecular characterisation of a mixed Cryptosporidium muris/Cryptosporidium felis infection in a cat

To date Cryptosporidium muris has been identified by microscopy and genotyping in cats in two studies. We report morphological and genetic evidence of a mixed C. muris and C. felis infection in a cat and provide the first histological, immunohistochemical, in situ hybridisation and genetic confirmation of a C. muris infection in the stomach of a cat. The cat suffered persistent diarrhoea after the initial consultation, which remained unresolved, despite several medical interventions. Further studies are required to determine the range, prevalence and clinical impact of Cryptosporidium species infecting cats.     

Prevalence of Cryptosporidium infection in dairy calves in western Washington

The prevalence and intensity of Cryptosporidium infection were examined in 445 Holstein calves at 10 dairy farms in western Washington, near Seattle. Fifty-one percent (176) of calves in the 7- to 21-day-old age group (n = 342) were positive for oocysts in the feces by carbolfuchsin staining. Prevalence and intensity of infection were highest in calves 8 to 14 days old; prevalence was 60% in this group, and 48% of the Cryptosporidium-positive calves had oocyst shedding at a 4+ level. A seasonal pattern in prevalence was not evident.     

Risk factors associated with Cryptosporidium parvum infection in cattle

A 2-year, cross-sectional study was conducted to identify risk factors for Cryptosporidium sp. infection in bovine farms in central Italy. Faecal samples were collected on 248 farms, from 2024 calves and analysed using ELISA and immunofluorescent assay (IFA) commercial kits. In all 101 samples confirmed to be positive with IFA, the aetiological agent was identified as Cryptosporidium parvumand a large genetic variability was detected by subtype analysis. The prevalence of farm infection ranged from 3.4% to 35.6%. Univariate analysis showed a number of putative risk factors, including the type of farm, stalling of calves, late supply of colostrum, number of heads and contact between calves and adults. However, multivariate analysis confirmed that the higher risk for calves was associated with housing calves separately from their dams, a characteristic practice of dairy herd, whereas calves being nursed by their dams, a characteristic of cow-calf herd resulted as a protective factor.     

Cryptosporidium infection as a cause of calf diarrhea

Cryptosporidiosis is a self-limiting protozoal disease of the intestinal tract. Although identified as possible agents of calf diarrhea less than 15 years ago, Cryptosporidium spp. are now believed to be common in calves and in many other host animal species worldwide. Recent literature on all aspects of cryptosporidiosis in calves is reviewed, predicaments in diagnosis and management are discussed, and public health concerns are raised.