Emerging Leptospira strain poses public health risk for dairy farmers in New Zealand
Emerging Leptospira strain poses public health risk for dairy farmers in New Zealand
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DOI：
10.1016/j.prevetmed.2019.104727
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发表时间：
2019-10-01
影响因子：
2.6
通讯作者：
Heuer, C.
中科院分区：
文献类型：
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作者：
Yupiana, Y.;Vallee, E.;Heuer, C.
在 20 世纪 80 年代引入奶牛疫苗接种之前，奶牛钩端螺旋体感染和奶牛场工人钩端螺旋体病在新西兰很常见。尽管乳制品行业内广泛接种疫苗，但疫苗接种的长期有效性和当前钩端螺旋体暴露状况仍然未知。 2016 年 1 月至 4 月进行了一项横断面研究，以调查致病性钩端螺旋体属的流行情况。牛和牛群尿液中的 DNA 及其与已知流行的五种钩端螺旋体血清型的关系。从国家数据库中随机选择了 200 个奶牛场。每个农场从成年奶牛身上采集了 20 对血液和尿液样本 (n = 4000)。使用显微凝集测试对血清型 Hardjobovis（称为 Hardjo）、Pomona、Copenhageni、Ballum 和 Tarassovi 进行测试，滴度 >= 48 被视为阳性。使用扩增 gryB 基因的定量实时 PCR (qPCR) 测试尿液。除一只牛群外，所有牛群都接种了二价 Hardjo/Pomona 疫苗或包含哥本哈根疫苗的三价疫苗。总共有 2.4% 的奶牛尿液 qPCR 呈阳性，27% 的农场至少有一头尿液 qPCR 阳性奶牛。总体而言，63% 的奶牛对一种或多种血清型呈血清反应阳性：Hardjo 为 44%，Pomona 为 28%，Copenhageni 为 15%（在接种疫苗的牛群中），对于未接种疫苗的奶牛：Copenhageni 为 1%，Ballum 为 3%，Tarassovi 为 17%。在 94 头 qPCR 尿液阳性奶牛中，51 头对 Tarassovi 呈血清反应，3 头对 Ballum 呈血清反应，3 头对 Copenhageni 呈阳性，24 头对 Hardjo 呈阳性，17 头对 Pomona 呈阳性，后两头可能反映了疫苗接种滴度。发现塔拉索维的脱落和血清学之间存在很强的关联。虽然没有证据表明当前的疫苗接种计划不能有效地预防目标血清变种，但塔拉索维血清变种显然已经出现在新西兰奶牛中。由于塔拉索维目前未包含在疫苗中，并且在乳制品工人通报的钩端螺旋体病病例中普遍存在，因此我们得出结论，该血清型对公共健康构成风险。
Leptospira infection in dairy cattle and leptospirosis in dairy farm workers were common in New Zealand prior to the introduction of dairy cattle vaccination in the 1980s. Despite widespread vaccination within the dairy industry, the long-term effectiveness of vaccination and current Leptospira exposure status remained unknown. A cross-sectional study was conducted from January-April 2016 to investigate the prevalence of pathogenic Leptospira spp. DNA in urine at cow and herd level, and its relationship to five Leptospira serovars known to be endemic. Two hundred dairy farms were randomly selected from the national database. Twenty paired blood and urine samples were collected on each farm from adult cows (n = 4000). Sera were tested using the Microscopic Agglutination Test against serovars Hardjobovis (termed Hardjo), Pomona, Copenhageni, Ballum and Tarassovi with titres >= 48 being considered positive. Urine was tested using quantitative real-time PCR (qPCR) that amplifies the gryB gene. All but one herd had been vaccinated with a bivalent Hardjo/Pomona or trivalent vaccine incorporating Copenhageni. In total, 2.4% of cows were urine qPCR positive and 27% of farms had at least one urine qPCR positive cow. Overall 63% of cows were seropositive to one or more serovars: 44% for Hardjo, 28% for Pomona, 15% for Copenhageni (in vaccinated herds), and for unvaccinated cows: 1% for Copenhageni, and 3% for Ballum and 17% for Tarassovi. Of the 94 qPCR urine-positive cows, 51 were seropositive to Tarassovi, 3 to Ballum, 3 to Copenhageni, 24 to Hardjo, and 17 to Pomona, the latter two presumably reflecting vaccination titres. A strong association was found between shedding and serology for Tarassovi. While there was no evidence that current vaccination programmes were ineffective in protecting against their target serovars, serovar Tarassovi has apparently emerged in NZ dairy cattle. As Tarassovi is currently not included in vaccines and is prevalent in notified leptospirosis cases in dairy workers, we concluded that this serovar poses a public health risk.