Archaeologists found 32 bony nodules scattered in the man's pelvic region, the largest about 0.9 inches (2.2 centimeters) in diameter. Such nodules are often a sign of tuberculosis, a lung infection caused by the bacterium Mycobacterium tuberculosis. Tuberculosis is the most common culprit in cases of calcified nodules, study leader Mark Pallen, a microbial genomist at Warwick Medical School in England, said in a statement.
Pallen and his colleagues sampled one of the nodules and subjected it to a process called "shotgun metagenomics." Instead of searching for a particular DNA signature, shotgun metagenomics takes the approach of simply sampling all the DNA present, just to see what turns up.
To the researchers' surprise, the man did not have tuberculosis. Instead, the bony nodule held the DNA signature of the bacterium Brucella melitensis, the microbe that causes brucellosis.
Brucellosis can be transmitted from livestock to humans in several ways. One possibility is that the man caught the disease from direct contact with animals - perhaps while slaughtering a sheep or delivering a newborn lamb. Or he could have gotten the disease from drinking unpasteurized milk or eating unpasteurized cheese. The Brucella strain that infected the man was a close relative of modern Italian strains, the researchers found, and sheep and goat herding have long histories in the region.