DNA from a microbe that is transmitted by body lice and can cause trench fever, was recently identified in a human tooth dating back more than 4000 years, according to a new report.

Currently, it is estimated that 14 percent of homeless people with body lice are infected with Bartonella quintana. The new findings suggest that infection with this bacterium is actually very old.

Dr. Didier Raoult, from Unite des Rickettsies in Marseille, France, and colleagues tested for B. quintana DNA in human molars obtained from an archeological site in southeastern France.

Radiocarbon dating indicated that the humans had died around 2100 BC.

As a comparison, teeth extracted in 2003 from patients with no evidence of B. quintana exposure were tested for microbial DNA.

One of the ancient molars harbored DNA that was identical to a known B. quintana gene fragment. Further testing of a related sequence revealed two mutations not previously described for the bacterium.

“The present study is the first to report an ancient ectoparasite-borne bacterial disease in humans,” the investigators write in the February 15th issue of The Journal of Infectious Diseases.

“These data may encourage scientists to use molecular techniques to explore ancient ectoparasites and human remains, in an attempt to research the history of ectoparasite-borne pathogens and to develop new insights into the coevolution of the host-bacteria relationship of B. quintana and humans.”

SOURCE: The Journal of Infectious Diseases, February 15, 2005.