BACKGROUND In 2018, an outbreak of leptospirosis was identified among raspberry workers from a mixed-berry farm in New South Wales, Australia. Initial testing had not revealed a cause, but eventually leptospirosis was detected via polymerase chain reaction (PCR). Further serological testing detected Leptospira borgpetersenii serovar Arborea, of which rodents are the predominant reservoir. Leptospirosis is rare in Australia, with outbreaks usually related to flooding. We conducted an investigation to identify risk factors for infection, to inform control measures. METHODS Cases were detected through laboratory notifications, hospital-based syndromic surveillance, awareness-raising among farm employees and clinician alerts. Confirmed cases had a four-fold rise in antibody titre or single titre ≥400 on microscopic agglutination test, and a positive IgM. Probable cases had a positive Leptospira PCR or IgM, and possible cases had a clinically compatible illness. We conducted a case-control study among raspberry workers on the farm and compared reported exposures between cases and seronegative controls. We assessed environmental risks on-site and tested rodents for leptospirosis. RESULTS We identified 84 cases over a 5-month period (50 confirmed, 19 probable and 15 possible). Compared with controls, cases were less likely to wear gloves and more recently employed. Cases also more commonly reported always having scratched hands, likely from the thorns on raspberry plants. We observed evidence of rodent activity around raspberry plants and three of thirteen trapped mice tested positive for Leptospira Arborea. Control measures included enhanced glove use, doxycycline prophylaxis and rodent control. CONCLUSIONS This is the largest known outbreak of leptospirosis in Australia. Workers were likely exposed through scratches inflicted during harvesting, which became contaminated with environmental leptospires from mice. Leptospirosis should be considered an occupational risk for raspberry workers, requiring protective measures. Chemoprophylaxis may assist in controlling outbreaks. PCR assists in the early diagnosis and detection of leptospirosis and should be included in surveillance case definitions.

中文翻译：

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2018年澳大利亚树莓工人中钩端螺旋体病暴发的调查和响应。

背景技术2018年，在澳大利亚新南威尔士州的一个混合浆果农场的树莓工人中发现了钩端螺旋体病暴发。最初的测试未发现原因，但最终通过聚合酶链反应（PCR）检测到钩端螺旋体病。进一步的血清学检测发现了博氏钩端螺旋体血清型的Arborea，其中啮齿动物是主要的储库。钩端螺旋体病在澳大利亚很少见，暴发通常与洪水有关。我们进行了调查，以找出感染的危险因素，并为控制措施提供依据。方法通过实验室通报，医院综合症状监测，农场员工意识增强和临床医生警报来发现病例。在显微镜凝集试验中，确诊病例的抗体滴度上升了四倍，或单价≥400，IgM阳性。可能的病例钩端螺旋体PCR或IgM呈阳性，可能的病例具有临床上相容的疾病。我们在农场的覆盆子工人中进行了病例对照研究，比较了病例与血清阴性对照之间的报道暴露。我们在现场评估了环境风险，并测试了啮齿动物钩端螺旋体病的啮齿动物。结果我们在5个月内确定了84例（确诊50例，可能19例，可能15例）。与对照组相比，病例戴手套的可能性较小，而最近才使用。还更普遍地报告病例总是被手抓伤，可能是由于覆盆子植物的刺刺引起的。我们观察到了覆盆子植物周围啮齿动物活动的证据，并且有十三只被困小鼠中的三只测试为Arborea钩端螺旋体呈阳性。控制措施包括加强手套使用，强力霉素的预防和啮齿动物的控制。结论这是澳大利亚已知的最大的钩端螺旋体病暴发。工人很可能会因收获期间造成的划痕而暴露，这些划痕已被小鼠的环境钩端螺旋体污染。钩端螺旋体病应被视为覆盆子工人的职业风险，需要采取防护措施。化学预防可能有助于控制疾病爆发。PCR有助于钩端螺旋体病的早期诊断和发现，应将其包括在监测病例定义中。钩端螺旋体病应被视为覆盆子工人的职业风险，需要采取防护措施。化学预防可能有助于控制疾病爆发。PCR有助于钩端螺旋体病的早期诊断和发现，应将其包括在监测病例定义中。钩端螺旋体病应被视为覆盆子工人的职业风险，需要采取防护措施。化学预防可能有助于控制疾病爆发。PCR有助于钩端螺旋体病的早期诊断和发现，应将其包括在监测病例定义中。