Smallpox, yellow fever, cholera, typhus. The very names of these recurring epidemic diseases struck fear and panic in the hearts of early Philadelphians. We 21st century citizens can hardly imagine what it must of felt like to be in a city under the plague flag. The recent warnings of potential terrorism through release of anthrax and smallpox remind us that epidemics visited this, then America’s largest city, on a regular schedule.

Recorded outbreaks of yellow fever struck the Delaware Valley in 1792, 1820, 1841, 1855 and 1865. Record-keeping and non-uniform diagnoses helped to underreport or misidentify epidemics. Smallpox hit Philadelphia in 1775, 1860, 1865 and 1868, and, according to one historian, helped create the United States of America.

Smallpox (etymologically speaking, variola, Latin for "stained," is the formal name for this virus. In England, "Small pockes," that is, pouches or sacs, was distinguished from the "great pockes," syphilis.) was first recorded by the ancients and some Egyptian mummies show scars on their preserved flesh. The first writer to theorize about acquired immunity was Abu Becr Mohammed ibn Zacariya al-Razi, known to the west as Rhazes (865?-925?). In his Treatise on Small-Pox and Measles, he noted that the disease was transmitted from person to person and did not develop in those who previously had "Chicken-Pox" (also translated as "light or mild pox").

Smallpox devastated the New World populations after the Conquistadores’ arrival and it is well to note that infectious disease and warfare always travel together. In 1763, a British army commander in the New England colonies proposed distributing smallpox-laden blankets to unfriendly tribes of native peoples in order to achieve his military objectives. The Home Office did not endorse this early attempt at biological warfare against "civilians." A few years later, many of the colonists themselves became the enemy of Britain during the American Revolution and once again, smallpox enlisted itself among the troops of both armies.

Treatment in Europe only began in 1717, when English aristocrats introduced to the inoculation or variolation technique learned from the physicians to the Ottoman court. Material from the pustules of those victims experiencing mild cases of smallpox was introduced through a cut in the arm of the healthy patient who would, hopefully, only manifest slight symptoms and complete immunity. Another officer, an American colonist, General George Washington watched helplessly as half his American troops died of smallpox at the battle for Quebec in 1775. The British soldiers had been inoculated and had the distinct military advantage of being alive and well enough to repulse all attempts at expanding the Revolution to Canada.

In a letter by John Adams dated April 13, 1777, General Washington visited Southeast Square, a Philadelphia city park which had become a graveyard for indigents and plague victims.

I have spent an hour this morning in the Congregation of the dead. I took a walk into the ‘Potter’s Field,’ a burying ground between the new stone prison and the hospital, and I never in my whole life was affected with so much melancholy. The graves of the soldiers, who have been buried, in this ground, from the hospital...during the course of last summer, fall and winter, dead of the small pox and camp diseases, are enough to make the heart of stone to melt away! The sexton told me that upwards of two thousand soldiers had been buried there, and by the appearance of the grave and trenches, it is most probable to me that he speaks within bounds. To what causes this plague is to be attributed, I don’t know - disease had destroyed ten men for us where the sword of the enemy had killed one!

Almost fifty years later, the first home (1825) of Jefferson Medical College would stand solemn watch over this plot of earth, the same year it was renamed, Washington Square, in honor of those smallpox victims it still contains. But during the hard winter of 1777 at Valley Forge, General Washington agonized over the health of his men. He had resisted the dangerous game of inoculation; it would take months to successfully treat his army and if quarantine was breached he would be the bearer of a full-blown epidemic. No doubt based on his earlier Quebec experience, he finally decided that since "the small pox has made such Head in every Quarter" his army would be inoculated, including new recruits who were to be variolated "as fast as they arrived" against this "most dangerous enemy." According to the full analysis of historian Elizabeth A. Fenn (Pox Americana: the Great Smallpox Epidemic of 1775-82, Hill and Wang, 2001.) the American troops, now able to fight at full strength, took a renewed vigor to the field and, by extension, helped win independence and found a lasting nation.

Edward Jenner (1749-1823) was the English medical pioneer who made the connection between exposure to cowpox and smallpox immunity by experimenting with dairymaids. His much safer "vaccination" (Latin for "cow") method and a worldwide cooperative effort finally rid the world of smallpox by 1980, as predicted by his friend, Thomas Jefferson, who wrote to Jenner in 1806, "Future generations will know by history only that the loathsome smallpox existed and by you has been extirpated." Jefferson himself in 1801 did one of the first vaccinations in North America. He vaccinated his family and numerous neighbors as well as the last of the Mohicans, Native American Chief Little Turtle. Jefferson’s lancet still exists as an iconic medical artifact. The smallpox strains are also known to exist in two high-security research laboratories in Atlanta and Moscow.

Related Links:

• List of U.S. epidemics
• More about yellow fever (Wikipedia)