新疆和静县巴音布鲁克羊新孢子虫感染状况横断面研究

为估计新疆和静县巴音布鲁克羊新孢子虫流行率，了解其在羊群中的感染情况，通过横断面研究方法，采用两阶段抽样策略，在和静县下辖的12个乡镇中抽取67个养殖场点，采集1 340份血清样品，使用间接ELISA方法检测新孢子虫抗体；通过问卷调查，分析群间传播相关风险因素。抗体检测结果显示，和静县巴音布鲁克羊新孢子虫感染的群表观流行率为32.84%（95%CI：21.85%~45.40%），真实流行率为 36.05%（95%CI：24.93%~49.93%）；12个乡镇中，有8个检出阳性场群。对问卷调查结果，进行卡方检验和Logistic回归分析发现，“饲养方式为舍饲”“建厂时间在6年以上”和“圈舍没有消毒”等因素具有统计学意义（P＜0.05），为养殖场感染新孢子虫的主要风险因素。结果表明：新孢子虫在和静县巴音布鲁克羊群中流行普遍，流行范围较广；长时间舍内饲养、建厂时间久、卫生消毒管理差是导致新孢子虫流行的主要风险因素。因此，提高养殖场户饲养管理水平，定期对圈舍进行消毒并保证一定的空圈时间，可降低新孢子虫的感染风险。     

蒙古国科布多省牛新孢子虫病PCR诊断初报

为了查明科布多省牛只是否感染犬新孢子虫(Neospora caninum)并造成流产隐患,本文应用PCR方法,以新孢子虫NC-5为诊断靶基因,对随机采集科布多省3个检测点的120份牛血样进行DNA提取、扩增诊断,并基因测序。结果显示,成功获得了231 bp目的片段;测序结果经BLAST比对,与犬新孢子虫新西兰株(GenBank登录号:AY459289.1)同源性达99%,构建的系统发育树中,本株与犬新孢子虫聚为一支,置信度达99%。说明科布多省牛只已感染了新孢子虫;在3个检测点中,艾尔登特苏木乡感染率最高,为12.7%(7/55),总感染率为7.5%(9/120)。本文初次报道蒙古国科布多省牛群不同程度的感染新孢子虫,应该引起重视。     

吉林省延边地区宠物犬与牧场家犬的新孢子虫病流行病学调查

为了调查宠物犬和牧场内家犬的犬新孢子虫病的感染情况,以新孢子虫Nc GRA2t为诊断抗原,应用间接酶联免疫吸附试验(ELISA)对采自吉林省延边地区部分宠物医院的23份宠物犬血清和牧场内家犬的4份血清进行了检测。结果,宠物犬的犬血清感染率为0%,牧场内家犬的感染率为75%。牧场内家犬的新孢子虫病感染率较高,牧场内饲养牛存在感染新孢子虫的风险。     

巴州部分地区黑头羊新孢子虫病的循环抗体检测

运用新孢子虫重组抗原-P36蛋白和P43蛋白作为包被抗原,对采自巴州部分地区的180份黑头羊血清样品进行新孢子虫病rELISA方法检测。结果表明：P36抗原检出率为15.56%（28/180）;P43抗原检出率为18.33%（33/180）。两种抗原平均检出率为16.94%,阳性符合率为84.85%。通过本次试验,基本掌握了巴州地区部分地区黑头羊新孢子虫感染情况,为今后对当地新孢子虫病的调查和预防提供了科学依据和理论支持。     

河南孟津地区6种引起奶牛流产病原的PCR检测及分析

为调查孟津地区引起奶牛流产的主要病原,本实验采集该地区8个规模化奶牛养殖场共52头新鲜流产胎牛,及其母体的血液、阴道分泌物和鼻腔分泌物。对所采集样本进行新孢子虫（N.caninum）、弓形虫(T.gondii)、胎儿三毛滴虫(T. foetus)、布氏杆菌(B.abortus)、牛传染性鼻气管炎病毒（IBRV）和牛病毒性腹泻病毒（BVDV）6种常见流产病原的PCR和RT-PCR检测。结果显示,被检样本总感染率为44.2%（23/52）,其中新孢子虫感染率最高,为32.7%（17/52）;IBRV次之,为13.5%（7/52）;胎儿三毛滴虫、布氏杆菌、弓形虫和BVDV感染率分别为1.9%、1.9%、1.9%和0。11.5%（6/52）的被检样本存在混合感染,其中以新孢子虫+IBRV混合感染为主（50%,3/6）。结合被检流产奶牛的临床特征及饲养管理等因素,推断新孢子虫是导致该地区奶牛流产的主要病原。     

犬新孢子虫速殖子接种妊娠矮小山羊引起流产,死胎和死产

犬新孢子虫引起的流产是美国和世界各地奶牛业的一个主要生产问题，感染新孢子虫而引起的流产了于矮山羊。我们给妊娠矮上山羊人工接种犬新孢子虫，以确定接种后否引起流产。试验用７只矮小山羊（１只对照，６只接种犬新孢子虫）。整个试验中，对照羊一直正常，且产下２只健康羔羊，接种犬新孢子虫的妊娠山辜发生流产，死胎和死产。妊娠早期（５１天）接种２只妊娠山关胎儿死亡和流产，或胎儿被吸收，流产胎儿的大脑、 心脏发现犬新     

感染犬新孢子虫泌乳奶牛流产后的早期恢复

本文旨在评价感染犬新孢子虫奶牛流产后的繁殖性能。在92头流产奶牛中,有68头牛为犬新孢子虫血清阳性,有24头为阴性。只给每天产奶量在25kg以上的流产后发情牛输精,在流产的30d中,当发情第一次输精时检查子宫复旧正常。在92头流产奶牛中,有73头(79.3%)妊娠,这其中有57头(83.8%)是犬新孢子虫血清阳性,有16头(66.7%)为阴性。经t-检验和秩和检验分析,妊娠天数及泌乳次数在犬新孢子虫血清阳性和阴性牛间没有差异,而犬新孢子虫血清阳性牛从流产到第一次人工授精的间隔时间、妊娠所需的授精次数,以及从流产到下一次妊娠的间隔时间都显著低于血清阴性牛(P0.0001)。经Log线性回归分析发现,牛群、泌乳次数、流产时的妊娠天数,以及从流产到人工授精所需时间对牛群没有显著影响。据优势比分析,犬新孢子虫血清阳性牛在流产后第一次人工授精妊娠的几率是血清阴性牛的6.22倍。在流产30d内对53头犬新孢子虫血清阳性牛(78%)授精,有26头(49%)妊娠,而仅1个血清阴性牛(4.2%)在30d内待授精,并且第一次授精后仍未孕。这些结果表明,感染犬新孢子虫的奶牛流产后一个月内可以授精,并有很高的生育率。建议早期检查犬新孢子虫血清阳性流产奶牛子宫复旧状况。     

新疆尼勒克县牛新孢子虫病PCR调查与分析

犬新孢子虫是牛流产的重要原因之一.为查清尼勒克县规模化养殖的牛群出现流产的原因,本文应用PCR检测方法,以新孢子虫NC5为诊断靶基因,对采自流产多发地—某乡8个养殖户的共计260份牛全血DNA进行诊断,并测序.结果显示,成功获得了231bp目的片段,新孢子虫病总感染率为5.0％;构建的系统发育树中,本株与Genbank...     

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。     

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。     

Prevalence of antibodies to Neospora caninum in dogs of rural or urban origin in central New Zealand

AIM: To investigate the seroprevalence of Neospora caninum infection in populations of dogs from dairy farms, sheep/beef farms and urban areas in the central part of New Zealand. It was postulated seroprevalence would be higher for farm dogs than urban dogs if the life-cycle of this parasite involves transmission between dogs and cattle.

METHODS: Serum samples were obtained from dogs that lived on dairy farms (n=161), sheep/beef farms (n=154) and in urban situations (n=150). The relative risk of detecting antibodies to N. caninum using an immunofluorescent antibody test (IFAT) was compared between farm and urban dogs.

RESULTS: The relative risk of having a titre of ≥1:200 to N. caninum was 2.43 (95% CI=1.88-3.14) for dairy-farm dogs and 3.16 (95% CI=2.48–4.02) for sheep/beef-farm dogs, compared with urban dogs. At this titre, which is currently used in New Zealand to indicate seropositivity, seroprevalence of N. caninum infection was 30.7% in urban dogs, 74.5% in dairy-farm dogs and 96.8% in sheep/beef-farm dogs.

CONCLUSION: This observation is consistent with a cycling of this disease between cattle and dogs on farms in New Zealand and with higher exposure of dogs to N. caninum on farms than occurs in urban environments. The prevalence of antibodies in all three groups of dogs tested in this study (dairy-farm dogs, sheep/beef-farm dogs and urban dogs) is higher than has generally been reported elsewhere. New Zealand farm dogs have a higher serological prevalence of N. caninum infection than urban dogs.

CLINICAL RELEVANCE: Management and disease control practices that break the life-cycle of transmission between cattle and dogs should assist in controlling cattle abortion due to N. caninum.     

Neospora caninum infection as a cause of reproductive failure in a sheep flock

Neospora caninum has been detected only sporadically in cases of ovine abortion, and it has therefore traditionally been considered as an unimportant parasite in small ruminants. This study was carried out with the aim of identifying the pathogen causing serious reproductive problems on a commercial sheep farm. Sera from all rams and ewes tested negative for antibodies against Border disease virus, Schmallenberg virus and Coxiella burnetii, and infections by these agents were therefore ruled out. Nevertheless, seropositivity to N. caninum and/or Toxoplasma gondii was detected, although the seroprevalence was higher in the case of N. caninum. The percentage of lambings and the number of lambs per dam were significantly lower in ewes that were seropositive to N. caninum while no effect on these parameters was detected in ewes that were seropositive to T. gondii. There was also no evidence of infection by T. gondii in the foetal/lamb tissues analyzed by PCR and/or immunohistopathological techniques. On the contrary, the DNA of N. caninum was detected in 13 out of 14 foetuses/lambs descendant from dams seropositive to this parasite. Characteristic lesions caused by N. caninum and/or its antigen were also detected. Genotyping of the N. caninum DNA revealed only two closely related microsatellite multilocus genotypes. The results clearly demonstrate that infection by N. caninum was the cause of the low reproductive performance of this sheep flock.     

Incidence and vertical transmission rate of Neospora caninum in sheep

The infection by Neospora caninum in sheep can lead to abortion and the birth of weak and debilitated lambs. The aim of this study was to assess the incidence of natural infection by Neospora caninum and the vertical transmission rate among sheep. A flock of 50 sheep was monitored for serum antibody titres against N. caninum and seroconversion over a period of six months using an indirect ELISA technique. The offspring of the herd was also investigated regarding anti-N. caninum antibodies to determine the vertical transmission rate through the indirect immunofluorescence technique. The initial and final prevalences of infection by N. caninum were 26.0% (13/50) and 72.0% (36/50), respectively, and the incidence of infection by N. caninum in the present study was 62.2% (23/37). The vertical transmission rate found was 15.4% (2/13). A high incidence of infection by N. caninum in sheep was observed, and this is the first report assessing the incidence of N. caninum among naturally infected sheep.     

Prevalence of anti-Toxoplasma gondii and anti-Neospora caninum antibodies in sheep from Mossoró, Rio Grande do Norte, Brazil

Toxoplasma gondii is an obligate intracellular parasite with a variety of hosts, responsible for reproductive problems and economic losses in sheep flocks. Neospora caninum was recently identified and its clinical presentation in sheep is similar to that of toxoplasmosis, which can cause repeated abortions, though less frequently in this species. In order to confirm the prevalence of these agents in the city of Mossoró, Rio Grande do Norte, Brazil, 409 serum samples from adult sheep (364 females and 45 males) were tested by the indirect immunofluorescence antibody test, using cut-off point at a dilution of 1:64 and 1:50 for T. gondii and N. caninum, respectively. From the 35 properties examined, 23 (65.7%) had at least one seropositive animal for T. gondii and six (17.1%) for N. caninum. The prevalence of seropositive animals for T. gondii was 20.7% and for N. caninum 1.8%. There was no association between the presence of the agent’s antibody and gender, reports of reproductive problems and presence of dogs and/or cats in the properties. T. gondii is well distributed and N. caninum has low prevalence in sheep and in the properties of the studied region.     

Effects of crossbreed pregnancies on the abortion risk of Neospora caninum-infected dairy cows

Previous studies have shown that the use of beef bull semen significantly reduces the rate of abortions due to Neospora caninum in artificially inseminated (AI) seropositive dairy cows. In addition, certain beef breeds could be more resistant to N. caninum infection and abortion than others. The aim of the present study was to determine whether different crossbreed pregnancies, those derived from Limousin, Charolais, Piedmontese or Belgian Blue semen, carry different risks of abortion in Neospora-infected dairy cows. The effects of possible interactions between maternal levels of N. caninum antibodies and the different breed crosses were also evaluated. The study was performed on five commercial Holstein–Friesian dairy herds in Northeast Spain with previously confirmed diagnoses of N. caninum infection in aborted foetuses. The study population was comprised of 1115 pregnancies: 633 pregnancies recorded after AI using Holstein–Friesian semen from 18 bulls and 482 after AI using beef semen from 27 bulls (304 inseminations using semen from Limousin bulls, 191 from Belgian Blue bulls, 89 from Piedmontese bulls and 49 from Charolais bulls). Abortion rates were 32.2% (155/482) and 15.2% (96/633) for seropositive cows inseminated with Holstein–Friesian and beef breed semen, respectively. Logistic regression analysis revealed the herd and the interaction between maternal N. caninum antibody titre and the different crossbreeds as significant factors affecting the abortion rate. Lowest abortion rates, similar to that shown by seronegative animals in the analysed herds (3.2%, 239/7432), were observed in dams AI using Limousin semen that had low (<30 relative index (RI) units) N. caninum antibody titres (2.1% abortion, 3/145) and these cows were used as reference. Compared to the cows used as reference, cows with low N. caninum antibody titres (<30 RI units) showed a similar risk of abortion when inseminated with Piedmontese or Charolais bull semen, but higher risk of abortion when inseminated with Holstein (17.9 times) or Belgian Blue (7.2 times) bull semen. All cows with high N. caninum antibody titres (≥30 RI units) had a higher risk of abortion, ranging from 8.9 times (cows inseminated with Limousine semen) to 37.8 times (cows inseminated with Piedmontese semen), compared to the cows used as reference. In conclusion, different crossbreed pregnancies carried different abortion risks in Neospora-infected dairy cows. The use of beef bull semen dramatically reduced the risk of abortion in dairy cows, especially if Limousin breed semen was used. Moreover, this reduction was found to be dependent on the N. caninum antibody titre such that the lowest incidence of abortions was recorded in Limousin semen inseminated cows with low antibody titres. Insemination of Neospora-seropositive cows with beef bull semen could both reduce the risk of abortion and avoid breeding replacements for infected cattle.     

Isolation of faecal chlamydia from sheep in Britain andtheir characterization by cultural properties

Faeces samples were taken per rectum from sheep on 26 farms in England and Wales and examined for thepresence of chlamydia by culture McCoy cell monolayers. Thirteen of the fars were known to have had abortion outbreaks associated with Chlamydia psittaci (enzootic abortion) and 13 were free of this infection. The chlamydia isolated were characterized by cultural techniques. Chlamydia were isolated from the faeces of lambs on all 26 farms and the prevalence of infection varied from 5–50% on individual farms. There was no significant difference between the proportion of infected lambs on farms where enzootic abortion was present or absent. Lambs first showed infection when they were 3 months old and the prevalence rate of infection increased up to 9 months old. No chlamydia were isolated from the faeces of 316 adult ewes. The chlamydia were identified as enteric rather than abortion type and thus were C. pecorum rather than C. psittaci.     

Prevalence of <Emphasis Type="Italic">Toxoplasma gondii</Emphasis> and <Emphasis Type="Italic">Neospora caninum</Emphasis> infections in sheep from Federal District,central region of Brazil

Serum samples from 1028 sheep were collected from 32 herds within Federal District, in the central region of Brazil. The samples were examined by indirect fluorescent antibody test (IFAT) using sera diluted 1:64 and 1:50 as cut-off values for the detection of antibodies against Toxoplasma gondii and Neospora caninum, respectively. The observed prevalence for T. gondii infection was 38.22% (26.81%<CI 0.95<49.62%), and the titers ranged from 64 to 65536. The observed prevalence for N. caninum infection was 8.81% (7.08%<CI 0.95<10.53%). The titers ranged from 50 to 51200. The reactant sera to both pathogens corresponded to 4.67% of the samples. The risk factors were not determined because of the absence of negative herds for T. gondii and the high proportion of positive herds for N. caninum (87.50%). The prevalence for T. gondii infection was significantly higher among males than in females. The present work is the first report on seroprevalence of T. gondii and N. caninum in sheep from Federal District and shows that infection by both parasites is widespread in the ovine population from this region.     

Coxiella burnetii shedding and environmental contamination at lambing in two highly naturally-infected dairy sheep flocks after vaccination

Abortion due to Coxiella burnetii was confirmed in the 2007/08 season in two naturally-infected dairy sheep flocks. Proportion of C. burnetii shedders and bacterial loads in vaginal mucus were high among aborted or lambed ewes, as was within-flock seroprevalence. Before the next reproductive season (2008/09) 75% of ewes and 50% of replacement lambs were vaccinated (Coxevac, CEVA Santé Animale) keeping the remaining as untreated controls. Compared with the previous year results when abortion outbreak started, a great reduction in the percentage of abortions, in the number of shedders and in the bacterial burden excreted by the ewes was found in both flocks. However, seroconversion in non-vaccinated yearlings from both flocks and the presence of C. burnetii DNA in bioaerosols taken at sheep premises at lambing indicated that infection was still active. No differences were observed between vaccinated and control groups in terms of proportion of C. burnetii shedders. These results suggest that optimal results of vaccination in heavily infected flocks may not be obtained in a short-term period.     

Relationship between Rainfall and Neospora caninum‐associated Abortion in Two Dairy Herds in a Dry Environment

The possible direct relationship between climate variations and abortion in Neospora caninum‐infected cows has not been studied. The objective of this study was to determine whether climate changes could be a risk factor for abortion in N. caninum‐infected cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection on aborted fetuses in two high‐producing dairy herds with a mean 27% seroprevalence of N. caninum antibodies. The final population study was comprised of 357 pregnancies in seropositive animals. Logistic regression analysis indicated no significant effects of herd, N. caninum antibody titre, climate variables during the first and third trimesters of gestation, mean and maximum temperature–humidity index values during the second trimester of gestation, and previous abortion on the abortion rate. Based on the odds ratio, a 1‐unit increase in lactation number yielded a 0.85‐fold decrease in the abortion rate. The likelihood of abortion was 1.9 times (1/0.54) lower for pregnant cows inseminated with beef bull semen compared with Holstein‐Friesian bull semen. The likelihood of abortion decreased significant and progressively by factors of 0.5, 0.41 and 0.3 for the respective classes 40–49, 30–39 and <30 rainfall mm during the second trimester of gestation (using the class ≥60 rainfall mm as reference). As a general conclusion, it seems that increased rainfall in a dry environment can compromise the success of gestation in N. caninum‐infected cows. Attempts should therefore be made to reduce environment effects during the second trimester of gestation, a period in which the immune response of cows is diminished.     

Associations between pregnancy outcome and serological response to Neospora caninum among a group of dairy heifers

AIM: To monitor pregnancy in a group of rising 2-year-old dairy heifers on a farm on which abortion due to Neospora caninum was known to occur in previous years.

METHODS: A prospective cohort study group of 164 rising 2-year-old heifers was pregnancy-tested and blood-sampled at 4–5-week intervals throughout gestation. Sera were tested for antibodies to N. caninum at 3–4-month intervals, using an enzyme-linked immunosorbent assay (ELISA). When loss of pregnancy was detected, an N. caninum indirect fluorescent antibody test (IFAT) was conducted retrospectively on stored sera collected the month before abortion, the month abortion was detected, and for the following 2 months, from heifers that aborted. All fetal and placental material detected following abortion was subjected to gross post-mortem and histopathological examination.

RESULTS: Eleven of 18 (61%) heifers that were seropositive and 4/146 (3%) heifers that were seronegative to N. caninum by ELISA, aborted. The relative risk for abortion among ELISApositive heifers was 23.6. Abortion occurred predominantly between Days 120 and 152 gestation among the ELISA-positive heifers and throughout gestation among the ELISA-negative heifers. IFAT titres rose around the time of abortion in most of the heifers that were previously seropositive by ELISA, but dropped rapidly again in post-abortion samples. IFAT titres among 4/6 ELISA-positive heifers that did not abort increased, but later in gestation than the time other heifers aborted. IFAT titres remained negative in heifers that aborted that were ELISAnegative.

CONCLUSIONS: Heifers that were seropositive to N. caninum by ELISA had a much greater risk of abortion than seronegative heifers. Most seropositive heifers showed evidence of a reactivation of infection during pregnancy. High (≥1:2,000) N. caninum IFAT titres also occurred in non-aborting heifers.

CLINICAL RELEVANCE: Culling of replacement heifers seropositive to N. caninum may be a cost-effective strategy for minimising risk of abortion. Pregnancy testing heifers before 5 months gestation may overestimate the number that calve in N. caninum-infected herds, but would assist in documenting the occurrence of abortion. Reliance on a high (>1:2,000) IFAT titre to rule-in N. caninum as a cause of abortion is likely to produce false-positive results.