ISEM UMR226, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France.
MIVEGEC, IRD, CNRS, Université de Montpellier, Montpellier, Centre IRD de Cayenne, Guyane française.
PLoS Negl Trop Dis. 2019 Jan 7;13(1):e0007074. doi: 10.1371/journal.pntd.0007074. eCollection 2019 Jan.
Zoonotic pathogens respond to changes in host range and/or pathogen, vector and host ecology. Environmental changes (biodiversity, habitat changes, variability in climate), even at a local level, lead to variability in environmental pathogen dynamics and can facilitate their transmission from natural reservoirs to new susceptible hosts. Whilst the environmental dynamics of aquatic bacteria are directly linked to seasonal changes of their habitat they also rely on the ecological processes underpining their transmission. However data allowing the comparison of these ecological processes are lacking. Here we compared the environmental dynamics of generalist and vector-borne aquatic bacterial pathogens in the same unit of time and space, and across rural and urban habitats in French Guiana (South America).
Using Leptospira sp. and Mycobacterium ulcerans we performed an environmental survey that allowed the detection of both pathogens in urban vs. rural areas, and during rainy vs. dry weather conditions. All samples were subjected to qPCR amplifications of LipL32 (Leptospira sp.) and IS2404 and KR (M. ulcerans) genetic markers. We found (i) a greater presence of M. ulcerans in rural areas compared with Leptospira sp., (ii) that modified urban environments were more favourable to the establishment of both pathogens, (iii) that Leptospira sp. presence was enhanced during the rainy season and M. ulcerans during the dry period, and (iv) differences in the spatial distribution of both bacteria across urban sites, probably due to the mode of dissemination of each pathogen in the environment.
We propose that in French Guiana simplified and modified urban ecosystems might favour leptospirosis and Buruli ulcer emergence and transmission. Moreover, disease risk was also constrained by seasonality. We suggest that the prevention of aquatic bacterial disease emergence in impoverished urban areas of developing countries would benefit from seasonal diseases targeted surveys, which would maximise limited budgets from cash-strapped health agencies.
人畜共患病病原体对宿主范围和/或病原体、媒介和宿主生态的变化作出反应。环境变化（生物多样性、栖息地变化、气候变异性），即使在地方一级，也会导致环境病原体动态的可变性，并促进它们从自然宿主传播到新的易感宿主。虽然水生细菌的环境动态与它们栖息地的季节性变化直接相关，但它们也依赖于支撑其传播的生态过程。然而，缺乏允许比较这些生态过程的数据。在这里，我们在同一时间和空间内，以及在法属圭亚那（南美洲）的农村和城市栖息地中，比较了普通和媒介传播的水生细菌病原体的环境动态。
使用钩端螺旋体和溃疡分枝杆菌，我们进行了一项环境调查，允许在城市与农村地区，以及在雨季与旱季条件下检测到这两种病原体。所有样本均接受了钩端螺旋体（Leptospira sp.）和 IS2404 和 KR（M. ulcerans）遗传标记的 qPCR 扩增。我们发现：（i）与钩端螺旋体相比，溃疡分枝杆菌在农村地区的存在更为普遍；（ii）改良的城市环境更有利于两种病原体的建立；（iii）钩端螺旋体的存在在雨季增强，而溃疡分枝杆菌在旱季增强；（iv）两种细菌在城市地点的空间分布存在差异，这可能是由于每种病原体在环境中的传播方式不同。
我们提出，在法属圭亚那，简化和改良的城市生态系统可能有利于钩端螺旋体病和伯里溃疡的出现和传播。此外，疾病风险还受到季节性的限制。我们建议，从现金拮据的卫生机构有限的预算中，通过针对季节性疾病的调查，最大限度地利用资金，来预防发展中国家贫困城市地区的水生细菌病的出现。
