环境因素对球虫卯囊孢子化的影响

探讨环境因素对球虫卵囊孢子化的影响,为切断鸡球虫病的感染途径提供依据。本实验将未孢子化球虫卵囊分别置于高温干燥、高温潮湿、室温三个不同环境中处理后,再按常规方法培养,并测其孢子化率。结果表明:80℃高温干燥环境中放置15 min以上,80℃高温潮湿环境中放置30 min以上,室温环境中放置1 d以上,卵囊均已完全丧失孢子化能力。     

Detection of Cryptosporidium parvum and Cryptosporidium muris in soil samples

 The flotation procedure for the detection of Cryptosporidium parvum and Cryptosporidium muris oocysts in feces was adapted for use on soil samples. Soil samples were seeded with known amounts of purified C. parvum or C. muris oocysts and Cryptosporidium spp.-free bovine feces. The limit of detection for this procedure was determined at different levels of inoculation for each species. At each level of inoculation, 30 control samples were processed and the observer was blind to the status of the sample. All samples were examined for the presence of Cryptosporidium spp. oocysts using phase-contrast microscopy. The samples were seeded with the following estimated counts of C. parvum oocysts: 1000/g, 1250/g, and 1500/g. These levels had sensitivities of 88%, 90%, and 93%, respectively. All inoculation levels had a specificity of 100%. Thirty additional samples were inoculated with C. muris and the limit of detection was found to be 76 oocysts/g sample, with a sensitivity of 97% and a specificity of 100%. Received: 4 October 1999     

Use of a novel soil tilting table apparatus to demonstrate the horizontal and vertical movement of the protozoan pathogen Cryptosporidium parvum in soil

A novel greenhouse based soil tilting table apparatus was used to investigate the potential for movement of the protozoan pathogen Cryptosporidium parvum both through and across a low permeability soil following the application of contaminated livestock waste to land. Soil blocks supported at an angle of 7.5% by the soil table were inoculated at one end with oocyst seeded slurry and subsequently irrigated at regular intervals over a 70-day period. Movement of the pathogen in runoff was demonstrated for at least 21 days and in one case in excess of 70 days from the time of inoculation. Water was also lost following percolation down through the soil profile and significant numbers of oocysts were also lost via this route, average numbers leached decreasing from 8.36±0.56×10⁶ at day 1 to 2.27±0.73×10⁴ at day 70. At the end of the study cores were removed from the soil blocks to determine the location of oocysts remaining within the soil. Numbers decreased down through the soil profile and as the distance from the point of inoculation increased so that 70 cm from the point of inoculation no oocysts could be detected in the soil at any depth. This implies that oocysts contained in runoff stay in the aqueous phase and do not precipitate out onto the soil surface, suggesting that even if the distances travelled are increased there may still be a significant pollution threat.     

鸡球虫的分离与感染试验

[目的]为探讨长期有效的鸡球虫病防控方法奠定基础.[方法]分离并培养鸡球虫卵囊,通过感染雏鸡试验研究其卵囊发育和感染的过程.[结果]分离到的球虫卵囊大多形态饱满,为宽椭圆形,少数为卵圆形,壁光滑,中间明显可见1个圆形核,原生质呈淡褐色,卵囊大小约为18.5～25.5 μm× 16.7～22.5 μm.正常的孢子化卵囊多能见到分化明显的4个孢子,18 h可看到部分卵囊孢子化,36h孢子化达80％.接种后发病雏鸡的体重缓慢增加,血便明显,死亡率较高,同时解剖可见盲肠病变明显,肠壁增厚,严重者因充满大量血液而盲肠肿大.[结论]根据卵囊的形态、发病鸡的临床表现、卵囊寄生部位和盲肠病理变化等特征,初步判断分离的球虫主要为柔嫩艾美耳球虫.     

Cryptosporidiosis in Horses of Urban Areas of Porto Alegre,Rio Grande do Sul,Southern Brazil

The aim of the present study was to detect the presence of Cryptosporidium spp. oocysts in the feces of horses used in military training and in horseback riding activities. A total of 90 fecal samples were collected from three sites in the city of Porto Alegre, state of Rio Grande do Sul, Brazil as follows: 71 samples were obtained from the Brazilian Army, seven from the hospital accredited with the School of Veterinary Medicine of Universidade Federal do Rio Grande do Sul, and 12 from a facility offering animal rest and training. All samples were collected between the months of January and February, 2008. They were screened microscopically for oocysts using the modified Ziehl–Neelsen staining technique. Oocysts were classified on the basis of their microscopic characteristics. The overall infection rate of horses as determined by microscopic analysis was 27.87% (25/90) and was identified only in horses raised in the Brazilian Army, with a rate of 35.21% (25/71). The morphometric analysis of oocysts revealed a mean size of 4.78 × 4.0 μm and a shape index of 1.16. None of the infected horses appeared to be clinically ill.     

Movement of the protozoan pathogen Cryptosporidium parvum through three contrasting soil types

The potential for transfer of the protozoan pathogen Cryptosporidium parvum through soil to land drains and, subsequently, water courses following the application of livestock waste to land was monitored in the laboratory using simulated rainfall and intact soil cores. Following irrigation over a 21-day period, Cryptosporidium parvum oocysts applied to the surface of soil cores (initial inoculum concentration 1×10⁸ oocysts core^–1) were detected, albeit in low numbers, in the leachates from clay loam and silty loam soils but not in that from a loamy sand soil. Variations in leaching patterns were recorded between replicate cores. At the end of the study soil cores were destructively sampled to establish the location of oocysts remaining within the soil. Distribution within cores was similar in all three soil types. The majority (72.8+-5.2%) of oocysts were found in the top 2 cm of soil, with numbers decreasing with increasing depth to 13.2±2.8%, 8.39±1.4%, and 5.36±1.4% at depths of 10, 20, and 30 cm, respectively.     

Toxoplasma gondii infection in cats from São Paulo state, Brazil: seroprevalence, oocyst shedding, isolation in mice, and biologic and molecular characterization

Cats are the most important hosts in the epidemiology of Toxoplasma gondii infections in humans and animals. Serologic and parasitological prevalence of T. gondii were determined in 237 cats from 15 counties in S?o Paulo state, Brazil. Antibodies to T. gondii were found in a 1:25 dilution of serum of 84 (35.4%) out of 237 cats by the modified agglutination test (MAT). Samples of brain, heart, tongue, and limb muscles (total 50 g) of 71 of the seropositive cats were pooled for each cat, digested in pepsin and bioassayed in mice. Faeces (1 g) from the rectum of each cat were examined microscopically for T. gondii-like oocysts and verified by bioassay in mice; T. gondii oocysts were found in the faeces of three (1.3%) of 237 cats. T. gondii was isolated from tissue homogenates of 47 cats. The DNA obtained from these 47 tissue isolates was characterized using the SAG2 locus: 34 (72.4%) isolates were type I, 12 (25.5%) were type III and one (2.1%) was mixed with types I and III. No type II isolates were detected. Most (23/34) of the type I isolates killed all infected mice and 7 of 12 type III isolates did not kill infected mice. Characterization of the SAG2 locus directly from tissue homogenates from 37 of 46 cats was successful. Genotypes obtained from these primary samples were the same as those from the corresponding isolates obtained in mice. Genotyping of the three oocyst isolates revealed that two were type I and one was type III. Molecular and biologic characteristics of T. gondii isolates from animals from Brazil are different from those from other parts of the world.     

柔嫩艾美耳球虫的抗原分析

本文采用十二烷基硫酸钠－聚丙烯酰胺凝胶电泳，免疫印渍技术，用抗柔嫩艾美耳球虫抗体分析了第二代型殖子、子孢子和未孢子化卵囊的蛋白质。ＳＤＳ－ＰＡＧＥ电泳银染表明第二代裂殖子主要蛋白质为：１７．６ＫＤ，２９．９ＫＤ，３８．９ＫＤ和５３．７ＫＤ，但用抗Ｅ．ｔｅｎｅｌｌａ抗体免疫印渍法检测出的主要抗原为：７８．０ＫＤ，８３．２ＫＤ和９５．５ＫＤ，这说明并不是含量高的蛋白质就是产生抗体的抗原；子孢子蛋白质含