Castex, D. | Search bioRxiv

bioRxiv2020

Five millennia of Bartonella quintana bacteremia.

Bartonella quintana caused trench fever in the framework of two World Wars and is now recognized as an agent of re-emerging infection. Many reports indicated the popularity of B. quintana exposure since the 90s. For evaluating its prevalence in ancient populations, we used real-time PCR to detect B. quintana DNA in 400 teeth collected from 145 individuals dating from the 1st to 19th centuries in nine archeological sites with the presence of negative controls. Fishers exact test was used to compare the prevalence of B. quintana detection in civil and military populations. B. quintana DNA was confirmed in a total of 28/145 (19.3%) individuals, comprising 78 citizens and 67 soldiers, 20.1% and 17.9% of which were positive for B. quintana bacteremia, respectively. This study collected previous studies on these ancient samples and showed that the presence of B. quintana infection followed the course of time in human history; a total of 14/15 sites from five European countries had a positive prevalence. The positive rate in soldiers was higher than those of citizens, with 20% and 18.8%, respectively, in the 18th - 19th centuries, but the difference in frequency was not significant. These results confirmed the role of dental pulp in diagnosing B. quintana bacteremia in ancient populations and showed the incidence of B. quintana in both citizens and soldiers. Many recent findings contributed to understanding the coevolution of the relationship between B. quintana and humans.

microbiology↗

bioRxiv2018

A phylogeography of the second plague pandemic revealed through the analysis of historical Y. pestis genomes

The second plague pandemic (14th - 18th century AD), caused by the bacterium Yersinia pestis, is infamous for its initial wave, the Black Death (1346-1353 AD), and its repeated scourges in Europe and the vicinity until the Early Modern Era. Here, we report 32 ancient Y. pestis genomes spanning the 14th to 17th century AD through the analysis of human remains from nine European archaeological sites. Our data support an initial entry of the bacterium from Eastern Europe and the absence of genetic diversity during the Black Death as well as low diversity during local outbreaks thereafter. Moreover, analysis of post-Black Death genomes shows the diversification of a Y. pestis lineage into multiple genetically distinct clades that may have given rise to more than one disease reservoir in, or close to, Europe. Finally, we show the loss of a genomic region that includes virulence-associated genes in strains associated with late stages of the second plague pandemic (17th - 18th century AD). This deletion could not be detected in extant strains within our modern dataset, though it was identified in a today-extinct lineage associated with the first plague pandemic (6th - 8th century AD), suggesting convergent evolution during both pandemic events.

evolutionary biology↗