Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Department of Medicine, University of Cambridge, Cambridge, United Kingdom.
Center for Vaccine Development and Global Health (CVD), University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
PLoS Negl Trop Dis. 2022 Jun 29;16(6):e0010178. doi: 10.1371/journal.pntd.0010178. eCollection 2022 Jun.
Typhoid fever epidemiology was investigated rigorously in Santiago, Chile during the 1980s, when Salmonella enterica serovar Typhi (S. Typhi) caused seasonal, hyperendemic disease. Targeted interventions reduced the annual typhoid incidence rates from 128-220 cases/105 population occurring between 1977-1984 to <8 cases/105 from 1992 onwards. As such, Santiago represents a contemporary example of the epidemiologic transition of an industrialized city from amplified hyperendemic typhoid fever to a period when typhoid is no longer endemic. We used whole genome sequencing (WGS) and phylogenetic analysis to compare the genotypes of S. Typhi cultured from acute cases of typhoid fever occurring in Santiago during the hyperendemic period of the 1980s (n = 74) versus the nonendemic 2010s (n = 80) when typhoid fever was rare. The genotype distribution between "historical" (1980s) isolates and "modern" (2011-2016) isolates was similar, with genotypes 3.5 and 2 comprising the majority of isolations, and 73/80 (91.3%) of modern isolates matching a genotype detected in the 1980s. Additionally, phylogenomically 'ancient' genotypes 1.1 and 1.2.1, uncommon in the global collections, were also detected in both eras, with a notable rise amongst the modern isolates. Thus, genotypes of S. Typhi causing acute illness in the modern nonendemic era match the genotypes circulating during the hyperendemic 1980s. The persistence of historical genotypes may be explained by chronic typhoid carriers originally infected during or before the 1980s.
20 世纪 80 年代，智利圣地亚哥对伤寒流行病学进行了严格调查，当时沙门氏菌血清 Typhi（S. Typhi）引起季节性、高度流行的疾病。有针对性的干预措施降低了每年的伤寒发病率，从 1977-1984 年的 128-220 例/105 人口降至 1992 年以后的<8 例/105。因此，圣地亚哥是一个工业化城市从放大的高度流行的伤寒到不再流行的时期的流行病学转变的现代例子。我们使用全基因组测序（WGS）和系统发育分析来比较在 20 世纪 80 年代高度流行期间（n = 74）和 2010 年代（n = 80）非流行期间从圣地亚哥急性伤寒病例中培养的 S. Typhi 的基因型，当时伤寒很少见。“历史”（20 世纪 80 年代）分离株和“现代”（2011-2016）分离株之间的基因型分布相似，基因型 3.5 和 2 构成了大多数分离株，80 株现代分离株中有 73 株（91.3%）与 20 世纪 80 年代检测到的基因型相匹配。此外，系统发育上“古老”的基因型 1.1 和 1.2.1 也被检测到，这两种基因型在全球收集的样本中都很少见，而且在现代分离株中也有明显的增加。因此，在现代非流行时期引起急性疾病的 S. Typhi 基因型与 20 世纪 80 年代高度流行时期流行的基因型相匹配。历史基因型的持续存在可能是由在 20 世纪 80 年代期间或之前感染的慢性伤寒携带者引起的。
