284 • The Great Plaguehandling plague patients detected the signs and symptoms used diagnosti-
cally by Hodges, Boghurst, and other 1665 caregivers and administered anti-
biotics immediately. Later diagnosis by laboratory results from the Pasteur
Institute confirmed the presence of Yersinia pestis.
Ecology and Evolution
Little genetic distance separates a rarely encountered mild food- and water-borne
zoonotic pathogen from one of the most feared pathogens of human history.
—B. Joseph Hinnebusch, “Bubonic Plague: A Molecular Genetic Case
History of the Emergence of an Infectious Disease” ( 1997 ), referring
toYersinia pseudotuberculosis and Yersinia pestisAIDS now appears to be the ultimate microbial challenge to contemporary
medical research. But the wily plague bacillus is not far behind with its speed
and stratagems. An obvious defense for persons in an endemic plague area is
vaccination. Several vaccines were used during the Vietnam War. Unfor-
tunately, the vaccine’s protection lasts only about six months, it offers no pro-
tection against pneumonic plague, and it carries potentially harmful side ef-
fects. Unless someone is traveling to an area where plague frequently infects
humans, the preferred strategy bypasses immunization, treating with anti-
biotics after a diagnosis of plague. Streptomycin has been the antibiotic of
choice. Alternative drugs (harder to find and more expensive) may be avail-
able if a patient has a resistant strain. The discovery in 1997 by Dr. Carniel
and her colleagues of plague strains in Madagascar resistant to multiple anti-
biotics, including streptomycin, chloramphenicol, and tetracycline, has
caused great concern.^43 In 2001 another strain resistant to streptomycin was
identified, again in Madagascar.
The slow pace of discovering new antibiotics is troubling. If drug-resistant
microbes should cause an epidemic, we might be returned to a pre-Pasteu-
rian world. This makes us wonder what could have caused the end of a cycle
of epidemics, as occurred in the late Roman Empire during the eighth cen-
tury and again in the eighteenth century in Europe. If scientists can deter-
mine what caused the pandemic of the Black Death to end after four centu-
ries in Europe without antibacterial intervention, perhaps this knowledge
may be adapted to our newest antimicrobial techniques.^44
Historical hindsight suggests that something happened to the cohabiting