Clinical surveillance of enteric pathogens like Salmonella is integral to track outbreaks and endemic disease trends. However, clinic-centered disease monitoring biases toward detection of severe cases and underestimates the incidence of self-limiting gastroenteritis and asymptomatic strains. Monitoring pathogen loads and diversity in municipal wastewater (MW) can provide insight into asymptomatic or subclinical infections which are not reflected in clinical cases. Subclinical infection patterns may explain the unusual observation from a year-long sampling campaign in Hawaii: Salmonella enterica serovar Derby was the most abundant pulsotype in MW but was detected infrequently in clinics over the sampling period. Using whole-genome sequencing data of Salmonella isolates from MW and public databases, we demonstrate that the Derby serovar has lower virulence potential than other clinical serovars, particularly based on its reduced profile of genes linked with immune evasion and symptom production, suggesting its potential as a subclinical salmonellosis agent. Furthermore, MW had high abundance of a rare Derby sequence type (ST), ST-72 (rather than the more common ST-40). ST-72 isolates had higher frequencies of fimbrial adherence genes than ST-40 isolates; these are key virulence factors involved in colonization and persistence of infections. However, ST-72 isolates lack the Derby-specific Salmonella pathogenicity island 23 (SPI-23), which invokes host immune responses. In combination, ST-72’s genetic features may lead to appreciable infection rates without obvious symptom production, allowing for subclinical persistence in the community. This study demonstrated wastewater’s capability to provide community infectious disease information—such as background infection rates of subclinical enteric illness—which is otherwise inaccessible through clinical approaches.

中文翻译：

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市政废水监测揭示了罕见病肠炎沙门氏菌血清型德比菌株的高度社区疾病负担。

沙门氏菌等肠道病原体的临床监测对于追踪疾病暴发和地方病趋势至关重要。但是，以临床为中心的疾病监测偏向于发现严重病例，并低估了自限性胃肠炎和无症状菌株的发生率。监测市政废水（MW）中的病原体负荷和多样性可以提供对无症状或亚临床感染的见解，而在临床病例中没有反映出这种情况。亚临床感染模式可能解释了在夏威夷进行的为期一年的采样活动中所观察到的异常现象：肠炎沙门氏菌血清德比是MW中最丰富的脉冲型，但在采样期间在临床上很少发现。使用沙门氏菌的全基因组测序数据从MW和公共数据库中分离出来的病毒，我们证明了Derby血清型的毒力潜力比其他临床血清型低，尤其是由于其与免疫逃逸和症状产生相关的基因谱减少，表明其具有亚临床沙门氏菌病的潜力。此外，MW具有丰富的稀有Derby序列类型（ST）ST-72（而不是更常见的ST-40）。ST-72菌株比ST-40菌株具有更高的纤维粘附基因频率。这些是感染定植和持续感染的关键毒力因子。但是，ST-72分离株缺乏德比特异性沙门氏菌致病岛23（SPI-23），它调用宿主的免疫反应。综合而言，ST-72的遗传特征可能导致明显的感染率，而没有明显的症状产生，从而使社区中的亚临床持续存在。这项研究证明了废水具有提供社区传染病信息的能力，例如亚临床肠道疾病的背景感染率，否则无法通过临床方法获得。