粪抗原检测法诊断犬细粒棘球绦虫感染的研究 Ⅰ.用细粒棘球绦虫成虫虫体抗原—抗体系统检测粪抗原方法的建立

用细粒棘球绦虫成虫虫体抗原及其免疫家兔血清ＩｇＧ建立了用于检测家犬粪抗原诊断细粒棘球绦虫成虫感染的双抗体夹心ＥＬＩＳＡ方法。对用离子交换层析、ＳＰＡ亲和层析、抗兔ＩｇＧ抗体亲和层析和细粒棘球绦虫成虫虫体抗原亲和层析等四种方法纯化的抗体进行了比较，以抗原亲和层析法纯化的抗体免疫活性最高，用双抗体夹心ＥＬＩＳＡ检测抗原的终点在标本缓冲液中为２．５ｎｇ／ｍｌ，在健康家犬粪便悬液的上清中为５ｎｇ／ｍｌ。检测１１只人工感染细粒棘球绦虫成虫的家犬粪便标本，粪抗原阳性率达１００％。     

粪抗原检测法诊断犬细粒棘球绦虫感染的研究Ⅲ.双抗体夹心ELISA法检测粪抗原诊断家犬细粒棘球绦虫感染的现场评价

本文报道用槟榔碱驱虫法对检测粪抗原诊断家犬细粒棘球绦虫感染的应用价值进行现场比较评价的结果。７３只受试犬中有１６只对槟榔碱无反应。在导泻成功的５７ 只犬中粪抗原阳性者１１只阳性率１９．２％ 。其中驱虫阴性的３８只犬中粪抗原阳性者仅２只（５．３％ ）。在１０只驱出细粒棘球绦虫的家犬中８只粪抗原阳性。５ 只驱出泡状带绦虫的犬中粪抗原阳性者１ 只,但反应强度低。粪抗原的反应强度与细粒棘球绦虫的感染强度呈正相关（ｒ＝ ０．９４）。证明本法可用于家犬细粒棘球绦虫感染的调查。     

Human cystic echinococcosis in two Mongolian communities in Hobukesar (China) and Bulgan (Mongolia)

In order to investigate the prevalence of human cystic echinococcosis (CE) in traditional Mongolian communities in western Mongolia and Xinjiang (northwest China), studies were carried out between 1995 and 2000, on two ethnically identical populations in Hobukesar (China) and Bulgan (Mongolia). The prevalence of human hepatic CE in the two communities was significantly different. In Hobukesar, human CE prevalence by ultrasound was 2.7% (49/1844), while in Bulgan it was 0.2% (4/1609) (P<0.001). Dog surveys showed that coproantigen-positive rates or dog necropsy positives were similar in both communities (35.0% in Hobukesar and 35.7% in Bulgan). Comparing possible risk factors, there appeared to be some significant differences between the two communities, which might contribute to the observed difference in CE prevalence. These included: the proportion of herdsman or farmers recorded; the proportions of dog ownership and livestock ownership; and the proportion of families practising home slaughter. The presence of a Russian dog-dosing programme up to the mid-1980s may explain the lower prevalence of human CE in the Bulgan population; no similar programme operated in the China-administered Hobukesar community.     

Modelling the spatial distribution of Echinococcus multilocularis infection in foxes

Alveolar echinococcosis is a rare but fatal disease in humans and is caused by the fox tapeworm Echinococcus multilocularis. The densities of fox and grassland rodent populations and the interactions between them influence E. multilocularis transmission rates in Europe. Successful rabies control has caused fox populations and E. multilocularis prevalence rates to increase in many European countries. The potential increase of the infection pressure on the human population motivates the monitoring of the infection status of foxes over space and time. Detection of E. multilocularis antigen levels in fox faecal samples collected in the field might provide a pragmatic methodology for epidemiological surveillance of the infection status in wildlife hosts across large areas, as well as providing an indication of the spatial distribution of infected faeces contaminating the environment. In this paper, a spatial analysis of antigen levels detected in faeces collected in the Franche-Comté region of eastern France is presented. In Franche-Comté, rodent outbreaks have been observed to originate in areas rich in grassland. Spatial trends in fox infection levels were modelled here as a function of the composition ratio of grassland in the landscape derived from the CORINE land-cover map. Kriging models incorporating the grassland trend term were compared to a variety of models in which five alternative trend expressions were used: the alternative trend expressions included linear and quadratic polynomials on the x and y coordinates with and without a grassland term, and a constant mean model. Leave-one-out cross-validation indicated that the estimation errors of kriging with a trend models were significantly lower when the trend expression contained the grassland index term only. The relationship between observed and predicted antigen levels was strongest when the estimated range of autocorrelation was within the home range size of a single fox. The over-dispersion of E. multilocularis in foxes may therefore account for the majority of spatial autocorrelation locally, while regional trends can be successfully modelled as a function of habitat availability for intermediate hosts.     

Detection of Coproantigens by Sandwich ELISA in Rabbits Experimentally Infected with Fasciola gigantica

Background

The study was targeted to report the appearance of coproantigens in feces and circulating antibodies in the serum of Fasciola gigantica experimentally infected rabbits.

Methods

Copro Hyper Immune Serum (HIS) and Excretory-Secretory Hyper Immune Serum (ES HIS) antigens were used in a sandwich ELISA for the detection of F. gigantica antigens in feces of 12 rabbits experimentally infected with different doses of F. gigantica encysted metacercariae (EMC) (10, 25 and 30 EMC). The relation between time of appearance of coproantigens in feces and anti-Fasciola antibodies in serum was evaluated.

Results

The earliest diagnostic coproantigen was recorded at 21^st, 25^th and 28^th day post-infection (p.i.) in groups of rabbits infected with 30, 25 and 10 F. gigantica EMC respectively. Both HIS and ES HIS were able to detect coproantigens in feces of rabbits infected with 30 EMC at day 21 p.i. The appearance of F. gigantica coproantigens in feces of infected rabbits was concurrent to the appearance of anti-Fasciola antibodies in blood (3^rd week p.i.). However, coproantigen has specific ability for direct assessment of active infection with minimal cross-reaction with other heterologous parasitic infections.

Conclusion

The findings hold promise for a more accurate diagnostic technique in the near future for suspected Fasciola infection.     

Evaluation of PCR based coprodiagnosis of human opisthorchiasis

In this study, a recently developed PCR test for the detection of Opisthorchis viverrini in human faecal samples was evaluated using two parasitological methods as references. During a survey of foodborne trematodes (FBT) in the Vientiane Province, Lao PDR, 85 samples were collected and evaluated for FBT eggs by the Kato Katz (KK) technique, the formalin ethyl acetate concentration technique (FECT) and a PCR analysis for the distinction between O. viverrini and other FBT. The two parasitological methods did not differ in the ability of detecting FBT eggs, and a single KK reading was characterized by a sensitivity of 85% when compared to two FECT readings. The PCR tested positive only in cases where eggs had been demonstrated by parasitological examination. However, the PCR tested negative in some samples with very high egg counts. Demonstrating a PCR sensitivity of approximately 50% in samples with faecal egg counts>1000, the previously reported PCR sensitivity based on in vitro studies was not supported. It is believed that technical problems rather than diagnostic reference related issues were responsible for the relatively low PCR performance. Further studies should aim at optimizing DNA extraction and amplification, and future PCR evaluation should include specificity control such as the scanning electron microscopy of eggs in test samples or the expulsion of adult trematodes from PCR tested individuals.     

四川省藏族牧区家犬棘球绦虫病流行病学调查研究(英文）

目的 对四川省甘孜县达通玛藏族牧区家犬感染细粒棘球棘球绦虫和多房棘球棘球绦虫进行流行病学调查和评价感染风险因素。 方法 分别对甘孜县达通玛藏族牧区查龙、卡龙、大德和查扎等4乡的犬主进行问卷调查,了解家犬感染棘球绦虫的相关因素。剖检流浪犬,检测棘球绦虫感染率,并用此结果评价粪抗原?鄄ELISA方法。用该方法检测家犬感染棘球绦虫的阳性率,评价犬驱虫效果。用χ2 检验和方差分析对结果进行统计。 结果 2000年流浪犬棘球绦虫感染率为60.9%（14/23）,其中细粒棘球绦虫感染率为26.1%（6/23）,多房棘球绦虫感染率为34.8%（8/23）。粪抗原?鄄ELISA特异性为80.0%,敏感性为92.3%。家犬粪抗原?鄄ELISA阳性率平均为50%（290/580）。从2003年起,经每半年1次吡喹酮犬驱虫（5 mg/kg）,2005年同一犬群粪抗原阳性率降为17.0%（99/580）。犬感染风险因素调查发现敞放犬粪抗原阳性率[40.4%（65/161）]明显高于半栓养犬[白天拴养夜晚放养的犬32.3%（109/337）;夜晚拴养白天放养的犬29.2%（21/72)]及一直栓养的犬[20%（2/10）] （P＜0.01）;主人缺乏防治相关知识的犬[38.1%（121/318）]和不进行驱虫的犬[47.7%（92/193）],阳性率明显高于主人具有相关知识[28.6%（75/262）]和驱虫犬[20.4%（79/387）] （P＜0.05 和P＜0.01）。粪抗原?鄄ELISA阳性率与犬的年龄、性别和饲养家畜的种类无关。 结论 四川省甘孜县达通玛藏族牧区是家犬两种棘球绦虫病流行区。粪抗原?鄄ELISA法可用于检测犬棘球蚴病。犬敞放和不对犬驱虫,以及牧民缺乏相关知识是造成家犬棘球蚴病传播、流行的重要原因。     

Reemergence of canine Echinococcus granulosus infection, Wales

As a consequence of large-scale outdoor slaughter of sheep during the 2001 foot and mouth disease (FMD) outbreak in the United Kingdom and the possibility of increased risk for transmission of Echinococcus granulosus between sheep and dogs, a large survey of canine echinococcosis was undertaken in mid-Wales in 2002. An Echinococcus coproantigen-positive rate of 8.1% (94/1,164) was recorded on 22% of farms surveyed, which compares to a rate of 3.4% obtained in the same region in 1993. Positivity rates between FMD-affected properties and unaffected ones did not differ significantly. Significant risk factors for positive results in farm dogs were allowing dogs to roam free and the infrequent dosing (>4-month intervals) of dogs with praziquantel. When these data are compared to those of a previous pilot hydatid control program in the area (1983-1989), an increase in transmission to humans appears probable.     

ELISA检测粪抗原诊断寄生虫感染的研究进展

双抗体夹心法ELISA检测寄生虫粪抗原,用于诊断寄生虫病或确定寄生虫感染,特别是肠道寄生虫感染,具有敏感、特异、快速,可区分现症感染与既往感染,且具有早期诊断和疗效考核价值等特点,是临床或现场个体检查及群体流行病学调查与监测的重要工具和手段。