ENHANCED understanding of syphilis is likely to emerge following a unique research project in which genomes of the bacteria that cause the condition were recovered from skeletal remains buried hundreds of years ago in Mexico. The team from the University of Tübingen, Germany, and the University of Zurich, Switzerland, believe the study provides the basis for a greater understanding of the history of this re-emerging infection.
Origins of Syphilis
Millions of new cases of sexually-transmitted syphilis are reported every year, but the origins of the disease are not well understood. This has led to much debate about which region of the world it emerged from to cause a 15th century syphilis pandemic in Europe. Efforts to study the condition in skeletal remains have been hampered by difficulties in distinguishing genetically between the subspecies of the bacterium Treponema pallidum which causes syphilis from that which causes yaws.
Treponemal DNA
For their study, the researchers analysed five skeletal remains from a historical site located in downtown Mexico City, which were selected because their skeletal features suggested they had a treponemal disease. Of these, three of the remains tested positive for treponemal DNA, each of which were infants and buried around 350 years ago during the colonial era.
Identification of Sub-Species
The team were able to discover the presence of the subspecies that causes syphilis, T. pallidum spp. pallidum, in two of these individuals and in the other, the yaws-causing T. pallidum ssp. pertenue. This was the first time the two had been distinguished between in skeletal remains. This new information has shed fresh light on the evolutionary history of syphilis. “Previous research that found the presence of T. pallidum ssp. pertenue in old world monkeys, and our finding that two T. pallidum subspecies likely caused similar skeletal manifestations in the past may suggest a more complex evolutionary history of T. pallidum than previously assumed”, commented Dr Alexander Herbig, University of Tübingen.
Further Investigation
Fundamentally, exciting new opportunities to study the disease more deeply have been provided by this first ever reconstruction of T. pallidum genomes from skeletal remains. “Further investigation of additional ancient samples from around the world will help to refine our understanding of this disease”, added Prof Johannes Krause, University of Tübingen.
James Coker, Reporter
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