Medicine and War

Immunization

The American invasion of Canada in 1775 failed because of a smallpox epidemic. Smallpox was so dangerous in the camps and on campaign that Gen. George Washington became convinced that only variolation (smallpox inocula-tion) could prevent the destruction of his army. Evidence of British efforts to infect American troops with smallpox strengthened Washington's resolve to pursue this course. Introduced in Boston in 1721, variolation consisted of inserting matter from a smallpox pustule under the skin of a healthy individual. A mild attack of the disease usually ensued, followed by lifelong immunity against smallpox. (Most British soldiers had either survived the disease in childhood or been inoculated in the military.) Because inoc-ulated soldiers actually contracted the disease, they had to be quarantined. But the military risks of troops temporarily sidelined were far less than those posed by an epidemic. The Continental Army's adoption in 1777 of mandatory inoculation was the most significant medical success of the Revolutionary War. A smallpox-free Army contributed sub-stantially to winning the war.

In 1798 British physician Edward Jenner introduced the safer method of vaccination (L. vaccinia, cowpox). Scratched into the skin of healthy subjects, cowpox virus (obtained from lesions on a cow's teat) conferred immunity to small-pox. Vaccination soon became the method of choice for pre-venting smallpox. On the eve of the War of 1812, Sec. of War William Eustis, a physician, ordered the vaccination of all American troops. Its success spurred Congress in 1813 to establish a vaccination program for civilians.

Smallpox mortality rates plummeted in the late 1800s as vaccination gained widespread acceptance, and a milder strain of smallpox, Variola minor, replaced the more viru-lent Variola major. By the 1970s Americans were no longer routinely vaccinated against smallpox. In 1979 the Global Commission for the Certification of Smallpox Eradication reported the eradication of the disease. In the 21st cen-tury, fears of bioterrorism have revived interest in small-pox vaccination.

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