Data from: Evidence of land-sea transfer of the zoonotic pathogen Campylobacter to a wildlife marine sentinel species

Environmental pollution often accompanies the expansion and urbanization of human populations where sewage and wastewaters commonly have an impact on the marine environments. Here, we explored the potential for faecal bacterial pathogens, of anthropic origin, to spread to marine wildlife in coastal areas. The common zoonotic bacterium Campylobacter was isolated from grey seals (Halichoerus grypus), an important sentinel species for environmental pollution, and compared to isolates from wild birds, agricultural sources and clinical samples to characterize possible transmission routes. Campylobacter jejuni was present in half of all grey seal pups sampled (24/50 dead and 46/90 live pups) in the breeding colony on the Isle of May (Scotland), where it was frequently associated with histological evidence of disease. Returning yearling animals (19/19) were negative for C. jejuni suggesting clearance of infection while away from the localized colony infection source. The genomes of 90 isolates from seals were sequenced and characterized using a whole-genome multilocus sequence typing (MLST) approach and compared to 192 published genomes from multiple sources using population genetic approaches and a probabilistic genetic attribution model to infer the source of infection from MLST data. The strong genotype-host association has enabled the application of source attribution models in epidemiological studies of human campylobacteriosis, and here assignment analyses consistently grouped seal isolates with those from human clinical samples. These findings are consistent with either a common infection source or direct transmission of human campylobacter to grey seals, raising concerns about the spread of human pathogens to wildlife marine sentinel species in coastal areas.

人口扩张与城市化进程常伴随环境污染问题，生活污水与废水通常会对海洋生态环境造成显著影响。本研究旨在探究人类来源的粪便源性细菌病原体向沿海海域海洋野生动物传播的潜在风险。研究从作为环境污染重要哨兵物种的灰海豹（Halichoerus grypus）体内分离出常见人畜共患病原菌弯曲杆菌（Campylobacter），并将其与野生鸟类、农业来源及临床样本中的分离株进行比对，以明确潜在的传播路径。在苏格兰五月岛（Isle of May）的灰海豹繁殖种群栖息地中，被采样的灰海豹幼崽有半数携带空肠弯曲杆菌（Campylobacter jejuni）：死亡幼崽的检出率为24/50，存活幼崽为46/90；该菌常与组织病理学病变证据相关联。返回该栖息地的一岁龄灰海豹（19/19）空肠弯曲杆菌检测结果均为阴性，这表明它们在离开该局部感染源栖息地期间清除了体内感染。研究人员对90株海豹来源的分离株进行全基因组测序与特征分析，采用全基因组多位点序列分型（whole-genome multilocus sequence typing, MLST）方法，并结合群体遗传学分析与概率性遗传溯源模型，将其与192株已公开的多来源分离株基因组进行比对，以基于MLST数据推断感染来源。较强的基因型-宿主关联性使得遗传溯源模型可应用于人类弯曲杆菌病的流行病学研究，本研究的分型归趋分析始终将海豹分离株与人类临床样本分离株归为同一聚类簇。上述研究结果支持两种潜在情形：一是二者共享同一感染源，二是人类携带的弯曲杆菌可直接传播给灰海豹，这引发了学界对人类病原体向沿海海域海洋野生动物哨兵物种传播的担忧。