Disease has plagued humans from the beginning of our existence. Cancer, including breast and prostate cancer, tuberculosis, sinusitis and dental disease affected the ancients worldwide. A third of all mummies studied show evidence of clogged arteries. It has recently been discovered that 5300-year old Ȍtzi, the Iceman, had H pylori, a bacterial infection that can cause stomach ulcers and must have made him very uncomfortable (A. Kraft, CBS News, Jan. 7, 2016). It can be found also in pre-Columbian Mexico so it was widespread. Diseases that thrive in large populations such as plague, influenza, measles and cholera did not become big killers until the rise of cities where they often determined the political and social outcome of history.
Smallpox has been a major threat and was present at least 5,000 years ago in northern Africa. It is estimated that at least one third of those infected died of the disease which was not controlled until 1798 when Edward Jenner introduced the vaccine. Before that, countless millions including many important leaders succumbed to it: Ramses V of the 18th dynasty in Egypt in 1156 b.c.e., Queen Mary II of Scotland in 1694, the Holy Roman Emperor, Joseph I in 1711, Russian Tsar Peter II in 1730 and French King Louis XV in 1774. Documents from India and China show massive infections there also, and it was smallpox that almost completely wiped out the Aztecs, Incas and other Amerindian populations in the Americas after the arrival of Spanish explorers (H. Whipps, Live Science, June, 2008). This event had global significance as the precipitous drop in the indigenous population allowed Europeans to freely occupy the devastated land.
A plague (perhaps Typhoid Fever) caused Athens to lose the Peloponnesian War in 430 b.c.e. It killed nearly a third of the population as well as the brilliant Athenian leader, Pericles. No other leader was up to the job and the city eventually fell to the Spartans. Another disease that probably lost a war was cholera in 218 b.c.e. when Hannibal set out to attack Rome with 50,000 troops and animals (Polybius and Livy say 80 elephants). Nearly half of Hannibal’s troops were lost crossing the Italian Alps (Polybius), probably because the first line would have had the use of pristine mountain streams but those streams would have been polluted by the time the last troops got to them. The war would likely have had a different outcome if Hannibal had not lost so many soldiers (and nearly all of the elephants).
A particularly bad type of malaria probably helped to cause the fall of the Roman Empire in the 5th century c.e. British scientists David Soren and Robert Sallares have found DNA evidence that reveals malaria as the cause of many children’s deaths (children are especially vulnerable to malaria) around Lugnano, Italy, and Roman writers tell of a pestilence there and that many people died of fevers. The labor shortage left swamps undrained allowing mosquitoes to spread so that Rome, a city of millions, was reduced to a town of only a few thousand (A. Thompson, BBC, Feb. 17, 2011) and unable to defend itself from attack.
A very devastating disease, the Bubonic Plague, has been found as early as 5th century b.c.e. in Egyptian mummies (E. Panagiotakopulu, Journal of Biogeography, 2004, 31) and sounds similar to the devastating wave that moved along trade routes from Asia through Europe in the 14th century c.e. That medieval plague killed at least seventy-five million people signaling the beginning of the end of Mongol power in Asia and ending the feudal system in Europe. That changed European society and economy and helped to foster an intellectual movement that led to the European Renaissance, the Reformation, and stimulated the scientific thinking that eventually spawned the Industrial Revolution (Whipps, April 2008).
Modern technology makes world-changing diseases less likely to alter history but the HIV epidemic and the recent ebola scare serve to remind us of the power of nature.