Outbreak of foetal infection with bovine pestivirus in a central Queensland beef herd

OBJECTIVE: To describe a significant outbreak of foetal infection and subsequent losses due to bovine pestivirus on a 5200 ha beef breeding and fattening property in central Queensland. DESCRIPTION OF THE HERD: The affected herd consisted of 656 cows, including 269 recently purchased cows, and 221 heifers that were joined in December/January 1995/96. There were approximately 2500 cattle on the property. INVESTIGATION: Following the purchase of 269 cows in October 1995, which were mingled with the existing cow herd, losses were experienced due to foetal infection with bovine pestivirus. These losses were recorded between 1996 and 1999 as: reduced pregnancy rates, losses between pregnancy testing (midpregnancy) and branding (calves averaged 3 months-of-age), losses due to pneumonia and ill-thrift between branding and approximately 12 months-of-age, and losses due to ill-thrift and the chronic wasting form of mucosal disease thereafter. All surviving calves were tested for bovine pestivirus in 1997 at an average of 10 months. Fifty-three calves were identified as persistently infected with bovine pestivirus. A further 110 calf losses could reasonably be attributed to bovine pestivirus infection. Persistently infected cattle were always unthrifty compared to their virus negative counterparts. Only one persistently infected calf was identified, on the basis of severe ill thrift, in the 1997 birth cohort and none in 1998. CONCLUSIONS: This outbreak of foetal infection with bovine pestivirus resulted in significant production losses. These losses were recorded over the three years subsequent to the outbreak. Significant numbers of persistently infected calves were not evident among calves born in the two years after this outbreak.     

Border disease in Norway. Serological examination of affected sheep flocks

Serological examination of 4 Border disease affected flocks of sheep using the neutralization test showed antibody prevalences between 14 and 96 %. Prevalence in yearlings in 3 of the 4 flocks was 37 %, it increased with age to 72 % in 5-year-old sheep. Possible reason for low prevalence (2 %) in yearlings in one of the flocks is discussed.     

A herd level analysis of a Corynebacterium pseudotuberculosis outbreak in a dairy cattle herd

Corynebacterium pseudotuberculosis infection in an Israeli dairy cattle herd is described. The disease was characterized by ulcerative granulomatous lesions, which occurred in an epidemic form. Thirty-two cows and two heifers were affected, the ratio of the number affected to number at risk being 17.5 : 1 and 9.5 : 1, respectively. The culling rate was 50% of the affected animals. Most of the affected animals were cows (91.2%), with one first-calving cow (2.9%) and two heifers (5.9%) also affected. The infection occurred during the summer to autumn months (August-December), and lasted 118 days. The incubation period is about 2 months. The disease appeared in two clinical forms - cutaneous and mastitic - or as a mixed form. C. pseudotuberculosis organisms that were isolated from the ulcerative granulomatous lesions and from milk samples failed to reduce nitrate. A decrease in milk production (4%) and an increase in the bulk-milk somatic cell count from a herd mean of 240 x 10(3) mL(-1) to 460 x 10(3) mL(-1) were noted during the morbidity period. The organism was isolated from milk samples of eight animals (25%). Clinical, epizootiological and microbiological aspects of the infection are described.     

An outbreak of sarcocystosis in a cattle herd.

In a cattle herd, 3 steers had anorexia and variable emaciation; 1 showed additional muscle stiffness, pyrexia, became recumbent and was killed in extremis. Gross changes in tissue specimens from this steer included grey-white foci in the skeletal muscle and a thickened, fibrous pleura. By histology interstitial pneumonia, myocarditis and necrotizing myositis were seen. There were wide-spread vascular lesions with endothelial damage, thrombosis and periarterial infiltrations. Sarcocystis-like schizonts were found in several organs, and different stages of thin-walled sarcocysts were seen in the myocardium. Examination of organs of 6 other steers in the same herd slaughtered 2 months later showed myocarditis, myositis, interstitial pneumonia and occasional vascular occlusions. There were a few schizonts in the spleen and lungs, and thin-walled sarcocysts were seen in the myocardium and skeletal muscle. It is concluded that development of vascular lesions probably represents an important step in the pathogenesis of sarcocystosis.     

鹿粘膜病病毒的分离鉴定

本研究首次应用MDBK传代细胞从腹泻幼鹿粪样中分离获得一株病毒(MDV N71).该毒株可使培养细胞出现明显的空泡变性,电镜负染观察接毒细胞培养物见有典型的粘膜病病毒粒子.MDV N71在MDBK传代细胞上的TCID50为10-5.4,对乙醚、氯仿和胰蛋白酶敏感,56℃ 70 min被灭活.对酸的耐受力较弱,在pH3.0环境下毒力明显降低.对碱有较强的耐受力,在pH9.0环境下依然稳定.不凝集绵羊、猪、兔和鸡红细胞.用MDV长春184毒株的特异性免疫荧光抗体染色(IFA),可以在感染细胞浆内见有特异性荧光.该毒株的致细胞病变作用,可被MDV长春184毒株抗血清所中和.提取病毒感染细胞的总RNA进行反转录聚合酶链反应(RT-PCR),结果扩增出的片段大小为400 bp.根据MDVN71的理化特性、形态学、生物学、免疫学和RT-PCR鉴定结果,确证MDV N71株为粘膜病病毒,这为深入探讨鹿MD的诊断和防制以及进行分子生物学研究奠定了基础.     

Association of herd BRSV and BHV-1 seroprevalence with respiratory disease and reproductive performance in adult dairy cattle

Background

The aim of this study was to detect the associations between bovine herpesvirus 1 (BHV-1) status of a herd and respiratory disease (BRD) occurrence and reproductive performance in pregnant heifers and cows. The association between management-related factors and higher BRD occurrence was also estimated.

Methods

Serum samples, collected from cows and youngstock from 103 dairy cattle herds, were analyzed for antibodies against BHV-1, bovine respiratory syncytial virus (BRSV), bovine viral diarrhoea virus (BVDV), and Mycoplasma bovis. A questionnaire was used to collect data concerning herd management factors and reproductive performance, as well as the occurrence of clinical signs of respiratory disease in the last two years, as evaluated by the veterinarian or farm manager. Multiple correspondence analysis (MCA) and logistic regression analysis were performed to identify and quantify the risk factors.

Results

A low to moderate prevalence (1-49%) of BRSV antibodies among youngstock was associated with a high occurrence of respiratory disease (OR = 6.2, p = 0.010) in cows and in-calf heifers. Employees of the farm may participate in the spread of such disease. Larger herd size, loose-housing of cows, housing youngstock separately from cows until pregnancy, and purchasing new animals were factors possibly related to a high occurrence of respiratory disease symptoms in pregnant heifers and cows. The highest risk of abortions (> 1.3%) and increased insemination index (number of inseminations per pregnancy) (> 1.9) occurred in herds with a moderate prevalence of BHV-1 antibodies (1-49%) in cows.

Conclusions

BHV-1 was not associated with acute respiratory disease in adult dairy cattle, however was significantly related to reproductive performance. BRSV possesses the main role in respiratory disease complex in adult dairy cattle.     

Seroprevalence of Neospora caninum infection following an abortion outbreak in a dairy cattle herd

OBJECTIVE: To investigate the seroprevalence of Neospora caninum infection in a commercial dairy cattle herd, 15 months after detection of an abortion outbreak. PROCEDURE: Sera from the whole herd (n = 266) were examined for N caninum antibodies by indirect fluorescent antibody test (IFAT) and immunoblot analysis. Herd records were reviewed to collate serological results with abortion history, proximity to calving, and pedigree data. RESULTS: The seroprevalence of N caninum infection was 24% (63/266) for IFAT titre > or = 160, 29% (78/266) for immunoblot positive (+ve), and 31% (82/266) for IFAT > or = 160 and/or immunoblot +ve; 94% (59/63) of animals with IFAT > or = 160 were immunoblot +ve. The association between seropositivity (IFAT > or = 160 and/or immunoblot +ve) and history of abortion was highly significant (P < 0.001); the seroprevalence was 86% (18/21) in aborting cows, compared with 30% (50/164) in non-aborting animals. The abortion rate for seropositive cows was 26% (18/68) compared with 3% (3/117) for seronegative animals. IFAT titres of infected cows were higher within 2 months of calving than at other times (P < 0.001). The association between seropositivity in dams and daughters was highly significant (P = 0.009). CONCLUSIONS: The abortions were associated with N caninum infection and there was evidence of reactivation of latent infection close to calving and congenital transmission of infection. Immunodominant antigens identified by immunoblots may prove useful for improved diagnostic tests.     

An outbreak of Streptococcus canis mastitis in a dairy herd in Israel

CASE HISTORY: An increase in the bulk somatic cell count (BSCC) of up to 1,000 × 10³ cells/ml occurred in a dairy herd in Israel at the end of 2001 and beginning of 2002.

CLINICAL FINDINGS: Bacteriological examination of milk from 69 cows revealed a high prevalence of Streptococcus group G bacteria, identified as S. canis, affecting 38% of cows and 20% of all quarters. Isolates were sensitive to cephalothin and moderately sensitive to penicillin G. Infected cows were separated from the herd, treated with intramammary antibiotics, milked last, and strict hygiene practices were introduced to the milking routine. The pathogen was cleared from the herd and BSCC decreased to 250-350 × 103 cells/ml after 6 months.

DIAGNOSIS: Streptococcus canis mastitis.

CLINICAL RELEVANCE: Streptococcus canis infection may cause subclinical mastitis and high bulk SCC in dairy herds and be resolved by treatment with intramammary antibiotics and the introduction of strict hygiene practices.     

An outbreak of Streptococcus canis mastitis in a dairy herd in Israel

CASE HISTORY: An increase in the bulk somatic cell count (BSCC) of up to 1,000 x 103 cells/ml occurred in a dairy herd in Israel at the end of 2001 and beginning of 2002. CLINICAL FINDINGS: Bacteriological examination of milk from 69 cows revealed a high prevalence of Streptococcus group G bacteria, identified as S. canis, affecting 38% of cows and 20% of all quarters. Isolates were sensitive to cephalothin and moderately sensitive to penicillin G. Infected cows were separated from the herd, treated with intramammary antibiotics, milked last, and strict hygiene practices were introduced to the milking routine. The pathogen was cleared from the herd and BSCC decreased to 250-350 x 103 cells/ml after 6 months. DIAGNOSIS: Streptococcus canis mastitis. CLINICAL RELEVANCE: Streptococcus canis infection may cause subclinical mastitis and high bulk SCC in dairy herds and be resolved by treatment with intramammary antibiotics and the introduction of strict hygiene practices.     

猪繁殖与呼吸综合征病毒持续感染与保护性免疫应答机制

对猪繁殖与呼吸综合征病毒持续感染与保护性免疫应答机制目前尚未完全阐明,有报道认为病毒中和抗体对抗感染不起保护性作用,甚至起负作用。近年来的研究结果表明,中和抗体在保护性免疫中起重要作用。文章针对猪繁殖与呼吸综合征病毒持续感染与清除,病毒抗原表位与中和抗体的产生机制,病毒感染动物免疫应答反应模型,病毒中和抗体在保护性免疫中的作用等内容做一综述。     

Contagious impetigo in a dairy cattle herd

Abstract Impetigo and fürunculosis appeared in a dairy cattle herd in association with intensive showering of the lactating cows during the summer months. Heifers and dry cows in the same herd, as well as those in a neighbouring herd in the same village, which was not showered and served as a comparison herd, remained unaffected. Skin lésions declined with the termination of showering. Only six animals [three cows (7.3%) and three first-calving cows (20%)] had to be treated parenterally with antibiotics. Resumen En un rebafio de vacas de leche aparecieron cuadros de impetigo y fürunculosis asociados a las duchas frecuentes aplicadas durante los meses de verano a las vacas lactantes. Las novillas y vacas secas en el mismo rebaño, asi como las de un rebaño vecino de la misma localidad y que no recibian duchas fueron usadas como rebaño de comparación, no se vieron afectadas. Las lesiones cutáneas remitieron al dejar de aplicar las duchas. Tan solo en seis animales [tres vacas (7, 3%) y tres vacas en primer parto (20%)] fue necesario aplicar una terapia parenteral con antibióticos. [Yeruham, I., Elad, D., Perl, S., Nyska, A., Vishinsky, Y. Contagious impetigo in a dairy cattle herd (Impetigo contagioso en un rebaño de vacas de leche). Veterinary Dermatology 1996; 7 : 239–242.] Résumé Impétigo et füronculose se sont manifestés dans un troupeau laitier, en relation avec un douchage intensif des vaches allaitantes pendant les mois d'été. Les jeunes et les vaches taries du même troupeau, ainsi que celles d'un troupeau voisin du même village, non douchées et servant d'élément de comparaison, restèrent inaffectés. Les lésions cutanées ont régressé dês la cessation des douchages. Seuls six animaux (trois vaches-7, 3%-et trois vaches primipares-20%-) durent etre traités par antibiothérapie parentérale. [Yeruham, I., Elad, D., Perl, S., Nyska, A., Vishinsky, Y. Contagious impetigo in a dairy cattle herd (Impétigo contagieux dans un troupeau de vaches laitières). Veterinary Dermatology 1996; 7 : 239–242.] Zusammenfassung Eine Impetigo und Furunkulose trat bei einer Milchviehherde in Verbindung mit intensivem Abduschen bei den laktierenden Kühen während der Sommermonate auf. Färsen und trockenstehende Kühe in der selben Herde sowie die einer Nachbarherde im selben Ort, die nicht abgeduscht wurden und als Vergleichsgruppe dienten, blieben unverändert. Die Hautveränderungen reduzierten sich mit Beendigung des Abduschens. Nur sechs Tiere (drei Kühe (7, 3%) und drei Kalbinnen (20%)) mußten parenteral mit Antibiotika behandelt werden. [Yeruham, I., Elad, D., Perl, S., Nyska, A., Vishinsky, Y. Contagious impetigo in a dairy cattle herd (Ansteckende Impetigo bei einer Milchviehherde). Veterinary Dermatology 1996; 7 : 239–242.]     

牦牛病毒性腹泻/粘膜病的防制研究

20世纪80年代以来，我国牦牛群中陆续发现牛病毒性腹泻／粘膜病(BVD／MD)，血清阳性率在30％～42．4％之间，病死率在30％左右，本研究先后从四川、西藏等地牦牛中分离出病毒，并对其进行各种生物学特征鉴定后，表明该病毒与标准毒属同一种，所不同的是四川牦牛病毒株属非致细胞病变型，即属NCP型。但回归本动物能复制出典型病例。目前尚无国产牛粘膜病疫苗用于生产。本研究依据猪瘟病毒与牛病毒性腹泻／粘膜病病毒具有交叉免疫性的原理，用猪瘟弱毒苗对牦牛病毒性腹泻／粘膜病进行预防，试验证明用猪瘟弱毒苗可以预防牛病毒性腹泻／粘膜病，且安全可靠，具有实用价值。     

Salmonella Typhimurium persistence in a Hunter Valley dairy herd

OBJECTIVE: An epidemiological study was undertaken at a Hunter Valley dairy with persistent Salmonella Typhimurium infection. The aim of the study was to identify cattle currently or previously infected with Salmonella, possible sources of the organism, patterns of spread, and husbandry practices that could be improved. METHODOLOGY: Faecal samples, feed, water and environmental samples were cultured for Salmonella and blood samples were tested for antibodies against Salmonella (Dublin and Typhimurium). A questionnaire was designed to identify possible risk factors associated with Salmonella excretion. RESULTS: S Typhimurium was apparently introduced from an old to a new dairy through manure spread as fertiliser. Salmonella apparently persisted in the effluent pond, and the following year clinical cases occurred after pasture, irrigated with water from the pond, was grazed by dry cows, and adult cattle became clinically ill with salmonellosis. The disease spread to other cows and calves. Poor design of calf pens assisted spread of Salmonella from sick to healthy calves. In addition, there was suspected transmission to the dairy farmer's 9-month-old daughter. Salmonellosis on a farm is a potential zoonotic risk to farm workers and their families. There is also the risk that cull cows may carry Salmonella to the abattoir and subsequently into the human food chain. Methods of waste management, and the design of calf pens, were identified as major risk factors that could be improved to minimise the spread of salmonellosis on this property.     

Investigation of an outbreak of mucosal disease in a beef cattle herd in southwestern Saskatchewan.

This study describes the epidemiological investigation of an outbreak of mucosal disease that occurred on a ranch in southwestern Saskatchewan. Over a six-month period during the fall and winter of 1991-1992, in a herd of 515 beef cattle and 96 bison, 20 yearling cattle from a group of 105 housed in one feedlot pen died from mucosal disease. A further eight yearlings were slaughtered for salvage because they were at risk of dying from mucosal disease. Mucosal disease mortalities were the first observed evidence of fetal infections with bovine viral diarrhea virus in this herd. Animals that died from mucosal disease exhibited signs of ill thrift prior to death. Deaths from mucosal disease were confined to the progeny of one herd of beef cows. Following an outbreak of fetal infection with bovine viral diarrhea virus during 1989-1990, at least 28 (22%) of the 128 calves born from this herd of cows in the spring of 1990 were persistently infected with bovine viral diarrhea virus. However, only one calf born from this herd in 1991, and five calves born from all herds in 1992 were persistently infected. Of the five persistently infected calves born in 1992, three were born to persistently infected replacement heifers born in 1990. These heifers calved without assistance in 1992, but only one of their calves survived past three days of age, and it was persistently infected. In January 1992, 82% of the total herd had reciprocal antibody titers to bovine viral diarrhea virus of > or = 1024 which suggested a high level of herd immunity to bovine viral diarrhea virus.(ABSTRACT TRUNCATED AT 250 WORDS)     

An acute outbreak of teat lesions affecting 38% of a dairy herd in Northland

Extract

Teat lesions are common in dairy cattle in New Zealand. Most of the infectious cases are caused by pseudocowpox virus, but lesions similar to those caused by bovine herpesvirus (BHV)-2 have been described clinically and confirmed serologically in New Zealand (Horner and Raynel 1988). BHV-2 and BHV-4 cause an acute viral disease in cattle known as bovine herpes mammillitis or ulcerative mammillitis (Hillerton et al 2001). Presumptive cases have been reported in New Zealand based on the nature and distribution of lesions (Daniel 1970). The disease is probably endemic in New Zealand but is poorly documented and generally considered to be mild and sporadic. The main differential diagnosis is pseudocowpox, which is often also present in herds affected with bovine herpes mammillitis, and dual infections of individual cattle have been reported (Gibbs et al 1972). To my knowledge, neither BHV-2 nor BHV-4 have yet been isolated in New Zealand.     

用中和免疫过氧化物酶试验检测牛血清中BVD/MD病毒

用中和免疫过氧化物酶试验检测内蒙、北京送检的26份牛血清中BVDV,检出阳性14份,将其中3份用荧光抗体法检测BVDV,均为阳性。试验表明,中和免疫酶试验用于BVDV检测前景广阔。     

牛病毒性腹泻病毒致病机制研究进展

牛病毒性腹泻（bovine viral diarrhea,BVD）和黏膜病（mucosal disease,MD）均是由牛病毒性腹泻病毒（bovine viral diarrhea virus,BVDV）感染引发的传染病,严重威胁世界养牛业的发展。文章概述了BVDV分型及其分子生物学特征,并从急性感染、经胎盘或子宫感染、持续性感染和黏膜病4个方面总结了近期国内外BVDV致病机制的研究进展。根据序列保守性及是否致细胞病变可将BVDV分为两种基因型和两种生物型,其中,新发现的"HoBi"株归类为瘟病毒属。BVDV基因进化很快,基因组编码4种结构蛋白和8种非结构蛋白,编码蛋白在病毒的复制、翻译及在宿主致病过程中发挥重要作用。BVDV致病机制复杂,急性感染会造成病毒血症、繁殖障碍、免疫抑制等,急性感染牛发生腹泻的原因与BVDV感染胃肠道的肌层、黏膜下层并干扰肠道神经的正常功能相关,非致细胞病变型（NCP）BVDV是造成急性感染的病因。胚胎感染BVDV取决于病毒首次侵袭时胎儿在子宫内的生长阶段。NCP型BVDV具有抑制胎儿体内产生Ⅰ型干扰素的能力,致使该病毒在宿主中得以生存并形成持续性感染牛,当持续性感染牛再次感染与NCP型BVDV高度同源的致细胞病变型（CP）毒株时直接诱发黏膜病。两种生物型的产生是发生持续性感染和黏膜病的重要因素,NCP型可向CP型BVDV进行转化。本综述有助于发现控制BVD-MD传播的新途径,为消灭该病和新型疫苗的研制提供参考。