Human leptospirosis in Seychelles: A prospective study confirms the heavy burden of the disease but suggests that rats are not the main reservoir.
Human leptospirosis in Seychelles: A prospective study confirms the heavy burden of the disease but suggests that rats are not the main reservoir.
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DOI：
10.1371/journal.pntd.0005831
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发表时间：
2017-08
影响因子：
3.8
通讯作者：
Tortosa P
中科院分区：
文献类型：
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作者：
Biscornet L;Dellagi K;Pagès F;Bibi J;de Comarmond J;Mélade J;Govinden G;Tirant M;Gomard Y;Guernier V;Lagadec E;Mélanie J;Rocamora G;Le Minter G;Jaubert J;Mavingui P;Tortosa P
钩端螺旋体病是由致病性钩端螺旋体引起的一种细菌性人畜共患病，大鼠被认为是其主要宿主。热带国家的疾病发病率较高，尤其是在岛屿生态系统中。我们的目标是确定塞舌尔（根据历史数据，该国排名世界第一）目前钩端螺旋体病的负担，建立动物宿主与人类疾病之间的流行病学联系，并确定传播的驱动因素。共有223名出现不明原因急性发热症状的患者参加了一项为期12个月的前瞻性研究，并通过实时PCR、IgM ELISA和MAT进行钩端螺旋体病检测。此外，还对主岛上被困的 739 只老鼠进行了肾携带钩端螺旋体的调查。所有分子证实的阳性样本均进一步进行基因分型。共有 51 名患者符合急性钩端螺旋体病的生物学标准，相当于每 100,000 名居民的年发病率为 54.6 例（95% CI 40.7–71.8）。黄鼠属中的钩端螺旋体运输。总体较低 (7.7%)，但褐家鼠 (52.9%) 显着高于家鼠 (4.4%)。问号钩端螺旋体是唯一在人类和大鼠中检测到的物种，由三种不同的序列类型 (ST) 代表。其中两种是在三分之二的人类急性病例中发现的新型 ST，而值得注意的是在大鼠中却没有。这项研究表明，人类钩端螺旋体病仍然是塞舌尔的一个沉重的疾病负担。基因型数据表明，老鼠实际上并不是人类疾病的主要宿主。我们强调，塞舌尔迄今为止实施的预防措施的效果相当有限。这可能是由于对排泄动物种群的控制措施无效造成的，也可能是由于对主要污染源的错误识别造成的。总而言之，所提供的数据刺激了对替代储存动物宿主的探索。钩端螺旋体病是一种新出现的环境传染病，由称为钩端螺旋体的螺旋形细菌引起。人类通常在娱乐或与工作相关的户外活动中通过接触动物宿主排出的尿液而被感染。作为一种人畜共患疾病，钩端螺旋体病是“同一个健康”概念的一个很好的例子，因为它将人类、动物和生态系统连接在一个病原体维持和传播的网络中。这种人畜共患疾病在热带地区特别是热带岛屿上非常流行。据报道，塞舌尔群岛是全球人类发病率最高的国家，尽管这些数字是基于过时的研究和/或不太具体的测试。本次调查旨在提供有关塞舌尔人类钩端螺旋体病负担的最新信息，并探讨其环境方面的传播链。提供的数据证实该疾病仍然严重影响该国。对人类急性病例中致病性钩端螺旋体的基因分型表明，该疾病涉及三种不同的序列类型（ST）。然而，通常被认为是塞舌尔主要宿主的老鼠只携带其中一种 ST，仅在少数人类病例中发现。因此，看来老鼠可能不是塞舌尔钩端螺旋体病的主要宿主，这对于采取预防措施以更好地控制人类钩端螺旋体病具有重要影响。
Leptospirosis is a bacterial zoonosis caused by pathogenic Leptospira for which rats are considered as the main reservoir. Disease incidence is higher in tropical countries, especially in insular ecosystems. Our objectives were to determine the current burden of leptospirosis in Seychelles, a country ranking first worldwide according to historical data, to establish epidemiological links between animal reservoirs and human disease, and to identify drivers of transmission. A total of 223 patients with acute febrile symptoms of unknown origin were enrolled in a 12-months prospective study and tested for leptospirosis through real-time PCR, IgM ELISA and MAT. In addition, 739 rats trapped throughout the main island were investigated for Leptospira renal carriage. All molecularly confirmed positive samples were further genotyped. A total of 51 patients fulfilled the biological criteria of acute leptospirosis, corresponding to an annual incidence of 54.6 (95% CI 40.7–71.8) per 100,000 inhabitants. Leptospira carriage in Rattus spp. was overall low (7.7%) but dramatically higher in Rattus norvegicus (52.9%) than in Rattus rattus (4.4%). Leptospira interrogans was the only detected species in both humans and rats, and was represented by three distinct Sequence Types (STs). Two were novel STs identified in two thirds of acute human cases while noteworthily absent from rats. This study shows that human leptospirosis still represents a heavy disease burden in Seychelles. Genotype data suggests that rats are actually not the main reservoir for human disease. We highlight a rather limited efficacy of preventive measures so far implemented in Seychelles. This could result from ineffective control measures of excreting animal populations, possibly due to a misidentification of the main contaminating reservoir(s). Altogether, presented data stimulate the exploration of alternative reservoir animal hosts. Leptospirosis is an emerging environmental infectious disease caused by corkscrew shaped bacteria called Leptospira. Humans usually get infected during recreational or work-related outdoor activities through contact with urine excreted by animal reservoirs. As a zoonotic disease, leptospirosis is a good example of the One Health concept for it links humans, animals and ecosystems in a web of pathogen maintenance and transmission. This zoonosis is highly prevalent in the tropics and especially in tropical islands. Seychelles archipelago has been reported as the country with highest human incidence worldwide, although figures are based on dated studies and/or poorly specific tests. The presented investigation aimed at providing an updated information on human leptospirosis burden in Seychelles and exploring the transmission chains in their environmental aspects. Presented data confirms that the disease still heavily impacts the country. Genotyping of pathogenic Leptospira in human acute cases reveals that three distinct Sequence Types (STs) are involved in the disease. However, rats typically considered as the main reservoir in Seychelles, harbor only one of these STs, found only in a minority of human cases. Hence, it appears that rats are likely not the main reservoir of leptospirosis in Seychelles, which has important consequences in terms of preventive measures to be implemented for a better control of human leptospirosis.