Detection of Vibrio cholerae aDNA in human burials from the fifth cholera pandemic in Argentina (1886–1887 AD)

Abstract

Objective: Detecting traces of ancient DNA of Vibrio cholerae to provide genetic information associated with the fifth cholera pandemic.Materials: Sediment samples from the sacral foramina of four individuals were analyzed, recovered from a mass grave near an institution dedicated exclusively to the isolation and treatment of citizens infected with cholera in the late 19th century in the city of Cordoba, Argentina.Methods: Paleogenetic techniques (ancient DNA extraction, PCR amplification, and Sanger sequencing) were applied. Specific primers for Vibrio cholerae (VCR, ctxA, ctxB, and tcpA) were designed.Results: By amplifying and sequencing the Vibrio cholerae repeats fragment, the infection in at least one individual was confirmed.Conclusions: The synthesis of the paleogenetic results with the archaeological and historical evidence strongly supports that at least one individual from the mass grave in Cordoba, Argentina, was a victim of the fifth cholera pandemic.Significance: Confirming the presence of the disease through multiple lines of evidence, including genetic, archaeological, and historical analyses, strengthens and affirms our understanding of the presence, effects, and potential evolutionary paths of the disease in the past.Limitations: Vibrio cholerae repeats were sequenced in one individual, while the remaining genes could not be amplified, which is likely related to gene copy number.Suggestions for future research: Paleogenetic examination of ancient samples from different locations will broaden our understanding of the origin, evolution, and past dissemination of Vibrio cholerae epidemic strains.