School of Biological Sciences, University of Aberdeen, Aberdeen, UK.
National Institute for Communicable Diseases, Division of National Health Laboratory Service, Johannesburg, South Africa.
Parasit Vectors. 2020 Nov 11;13(1):570. doi: 10.1186/s13071-020-04444-0.
Rattus spp. are frequently implicated as key reservoir hosts for leptospirosis, one of the most common, but neglected, bacterial zoonoses in the world. Although leptospirosis is predicted to be a significant public health threat in Africa, studies from the continent are limited.
Rattus spp. (n = 171) were sampled (January-May 2016) across the City of Johannesburg, South Africa's largest inland metropole. Rattus spp. genetic diversity was evaluated by full length (1140 bp) cyt b sequencing of 42 samples. For comparison, a further 12 Rattus norvegicus samples collected in Cape Town, South Africa's largest coastal metropole, were also genotyped. Leptospira infections were identified and genotyped using real-time PCR and multi-locus (lfb1, secY and lipL41) DNA sequencing.
Five R. norvegicus haplotypes were identified across Johannesburg, four of which have not previously been detected in South Africa, and one in Cape Town. Across Johannesburg we identified a Leptospira spp. infection prevalence of 44% (75/171) and noted significant differences in the prevalence between administrative regions within the metropole. Multi-locus sequence analyses identified a clonal genotype consistent with L. borgpetersenii serogroup Javanica (serovar Ceylonica).
The prevalence of infection identified in this study is amongst the highest detected in Rattus spp. in similar contexts across Africa. Despite the complex invasion history suggested by the heterogeneity in R. norvegicus haplotypes identified in Johannesburg, a single L. borgpetersenii genotype was identified in all infected rodents. The lack of L. interrogans in a rodent community dominated by R. norvegicus is notable, given the widely recognised host-pathogen association between these species and evidence for L. interrogans infection in R. norvegicus in Cape Town. It is likely that environmental conditions (cold, dry winters) in Johannesburg may limit the transmission of L. interrogans. Spatial heterogeneity in prevalence suggest that local factors, such as land use, influence disease risk in the metropole.
In South Africa, as in other African countries, leptospirosis is likely underdiagnosed. The high prevalence of infection in urban rodents in Johannesburg suggest that further work is urgently needed to understand the potential public health risk posed by this neglected zoonotic pathogen.
褐家鼠等鼠种常被认为是钩端螺旋体病的主要储存宿主，钩端螺旋体病是世界上最常见但被忽视的细菌性人畜共患病之一。尽管钩端螺旋体病预计将成为非洲的重大公共卫生威胁，但来自该大陆的研究有限。
2016 年 1 月至 5 月，在南非最大的内陆大都市约翰内斯堡采集了褐家鼠等鼠种（n=171）。通过对 42 个样本的全长（1140bp）细胞色素 b 测序评估了褐家鼠等鼠种的遗传多样性。为了进行比较，还对南非最大的沿海大都市开普敦采集的另外 12 只挪威鼠进行了基因分型。使用实时 PCR 和多基因座（lfb1、secY 和 lipL41）DNA 测序鉴定和基因分型钩端螺旋体感染。
在约翰内斯堡发现了 5 种挪威鼠的单倍型，其中 4 种以前在南非没有发现，1 种在开普敦发现。在约翰内斯堡，我们发现钩端螺旋体感染的流行率为 44%（75/171），并注意到大都市内各行政区之间的流行率存在显著差异。多基因座序列分析鉴定了一种与伯氏钩端螺旋体血清群爪哇型（血清型锡兰型）一致的克隆基因型。
本研究中在褐家鼠等鼠种中检测到的感染率是在非洲类似背景下检测到的最高感染率之一。尽管在约翰内斯堡鉴定的挪威鼠单倍型存在异质性，表明其入侵历史复杂，但所有感染啮齿动物中均鉴定出单一的伯氏钩端螺旋体基因型。在以挪威鼠为主的啮齿动物群落中没有发现问号钩端螺旋体是值得注意的，因为这些物种之间广泛存在宿主-病原体的关联，并且在开普敦的挪威鼠中发现了问号钩端螺旋体感染的证据。约翰内斯堡寒冷干燥的冬季可能限制了问号钩端螺旋体的传播。流行率的空间异质性表明，土地利用等局部因素可能会影响大都市的疾病风险。
在南非，与其他非洲国家一样，钩端螺旋体病可能被漏诊。约翰内斯堡城市啮齿动物的高感染率表明，迫切需要进一步研究以了解这种被忽视的人畜共患病病原体可能带来的公共卫生风险。
