Seroprevalence and Influence of Bovine Leukemia Virus on the Incidence of Mastitis in Dairy Herds
Seroprevalence and Influence of Bovine Leukemia Virus on the Incidence of Mastitis in Dairy Herds
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DOI：
10.22456/1679-9216.109458
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发表时间：
2021-01-26
影响因子：
0.2
通讯作者：
Di Filippo, Paula Alessandra
中科院分区：
文献类型：
--
作者：
de Almeida, Italo Camara;Hatum de Almeida, Sayanne Luns;Di Filippo, Paula Alessandra
背景资料：地方性牛白血病（EBL）是一种慢性病毒性疾病，其病原体是一种致癌的δ逆转录病毒，称为牛白血病病毒（VLB）。它在奶牛群中广泛分布，可能需要几年时间才能出现第一次临床表现。VLB血清反应阳性的动物更容易发生感染性疾病，如乳腺炎。本研究的目的是评估巴西圣埃斯皮里托的Caparao地区的EBL血清阳性率、乳腺炎的患病率、白血病和乳腺炎之间的可能关联以及与白血病相关的危险因素。对854头临床健康的杂交牛进行了地方性牛白血病的流行率及其与乳房炎的关系的研究在2015年2月至12月期间，使用来自巴西圣埃斯皮里托南部Caparao Capixaba微区12个自治市农场的不同泌乳期（Bos tauros tauros x Bos tauris indicus）奶牛。EBL的血清阳性率用琼脂扩散试验确定，临床型乳腺炎的存在用黑色背景杯试验确定，隐性乳腺炎的存在用CMT确定。针头的重复使用、挤奶类型、生殖管理、小牛死亡率、生殖问题的存在和产奶量是评估的风险因素。通过比值比（95%置信区间）估计变量之间的关联。相关性的显著性通过卡方检验确定。调查对象中，FBI型、临床型和隐性乳房炎的患病率分别为56.79%、5.50%和43.55%。EBL病毒感染与隐性乳房炎的发生呈正相关（P < 0.05，OR = 1.41，CI = 1.07-1.86）。一次性针头的重复使用（OR = 1.92，CI = 1.46-2.53），机械挤奶（OR = 2.03，CI = 1.34-3.08），犊牛死亡率（OR = 2.39; CI = 1.25-4.55）和存在生殖问题（OR = 1.62，CI = 1.23-2.14）为LEB的危险因素（P < 0.05）。农民对EBL缺乏了解，未能采取控制和消除措施，有利于牛群中出现新病例。动物年龄、购买动物时未进行检查、重复使用直肠触诊手套和针头等因素均有助于感染的传播。与隐性乳房炎相关的经济损失甚至可能大于临床型乳房炎造成的经济损失。临床型乳房炎患病率的差异可能与饲养制度、管理类型、集约化程度和生产水平有关。在这种情况下，我们注意到大量动物出现亚临床感染，而农民可能无法察觉到这种损失。得出的结论是，EBL是广泛存在于卡帕劳圣埃斯皮里托的地区的城市的奶牛群。在调查的一些城市，临床型和亚临床型乳腺炎的患病率很高。EBL的存在增加了发生亚临床乳腺炎的机会。一次性针头的重复使用和机械挤奶被认为是与EBL相关的风险因素。EBI血清反应剂动物更可能出现小牛死亡和生殖问题。有必要讨论该地区的最佳卫生管理制度，并作出更好的经济和社会反应，然后通过技术援助制定教育和执行措施。
Background: The enzootic bovine leukosis (EBL) is a viral disease with a chronic aspect and its etiological agent is an oncogenic deltaretrovirus called bovine leukemia virus (VLB). It has a wide distribution in dairy cattle herds, and it may take several years before the first clinical manifestations occur. Animals seropositive for VLB are more susceptible to developing infectious diseases such as mastitis. The objective of this study was to evaluate the seroprevalence of EBL, the prevalence of mastitis, the possible association between leukosis and mastitis, and the risk factors related to leukosis in municipalities of the Caparao region of Espirito Santo, Brazil.Materials, Methods & Results: The prevalence of enzootic bovine leukosis and its association with mastitis were evaluated in an 854 clinically healthy crossbred (Bos tauros tauros x Bos taurus indicus) dairy cows were used, in different lactation phases, from farms located in the 12 municipalities that compose the Caparao Capixaba micro-region, in the southern part of Espirito Santo, Brazil, in the period from February to December 2015. The seroprevalence of EBL was determined by the agar gel immunodiffusion test, the presence of clinical mastitis was ascertained by the black background mug test and of subclinical mastitis by the CMT. The reuse of needles, type of milking, reproductive management, calf mortality, presence of reproductive problems and milk yield were the risk factors assessed. The association between the variables was estimated by the odds ratio (95% confidence interval). The significance of the associations was determined by the Chi-square test. The prevalence of FBI-, clinical and subclinical mastitis was 56.79%, 5.50% and 43.55%, respectively. There was a positive association between the EBL virus and the presence of subclinical mastitis (P < 0.05, OR = 1.41, CI = 1.07-1.86). The reuse of disposable needles (OR = 1.92, CI = 1.46-2.53), mechanical milking (OR = 2.03, CI = 1.34-3.08), calf mortality (OR = 2.39; CI = 1.25-4.55) and the presence of reproductive problems (OR = 1.62; CI = 1.23-2.14) were considered risk factors associated with LEB (P < 0.05).Discussion: Enzootic bovine leukosis is disseminated in the dairy herds in the municipalities the study. The lack of knowledge about EBL among farmers and the failure to adopt measures for its control and elimination favor the appearance of new cases in the herd. Factors such as animal age, absence of exams when purchasing animals, reuse of gloves for rectal palpation and needles, contribute to dissemination of the infection. The economic losses associated with subclinical mastitis can even be greater than those caused by clinical mastitis. The differences for prevalence of clinical mastitis can be associated with the breeding system, type of management, intensification and level of production. In this context, we noted a much larger number of animals with subclinical infection, where the losses may not be perceptible to the farmers. It is concluded that EBL is widespread in dairy herds of the municipalities of Caparao Espirito Santo's region. The prevalence of clinical and subclinical mastitis is high in some cities surveyed. The presence of EBL increases the chances of developing subclinical mastitis. The reuse of disposable needles and mechanical milking were considered risk factors associated with EBL. Seroreagent animals for EBI, are more likely to present calf mortality and reproductive problems. It is necessary to discuss the best sanitary management system for the region, with a better economic and social response and then carry out the elaboration of educational and implementation measures, through technical assistance.