Cecil gave the ‘pro’ argument for syphilis
being introduced to the old world from the
new. Certainly popular culture has given
this attribution also (e.g., Voltaire’s
Candide, in which Dr. Pangloss’s syphilis
is traced back to Columbus).
For the ‘con’ argument, science cannot
discern any organic difference between the
spirochete that causes syphilis and that
which causes yaws. Yaws is well known to
have existed long before Columbus.
Yaws is a non-existent or nearly non-existent
disease these days. It is marked by skin
sores and lesions, and is spread by contact
presumably between sores and cuts, abrasions,
etc… The development of woolens and
textiles probably had an enormous impact
(downwards) on the incidence of this disease
in Europe soon after the millenium. It may
(or may not) be the case that the disease
simply shifted its primary transmission mode
about the time of Columbus.
Alas, we will probably never know. Still,
if the genome for syphilis and yaws (if the
spirochete or its bits can be obtained from
european sources prior to 1493), and they
in fact turn out to be identical or nearly
so, it would provide strong evidence against
syphilis being solely a new world disease
prior to 1492.