Table of Contents • I. Poliomyelitis, Treatment, and Prevention Prior to 1955 • A. Poliovirus and Poliomyelitis • B. The Endemic Phase (Antiquity to ~1880) • C. Epidemic Emergence (1880-1920) • D. The Epidemic Phase (1920-1955) • E. The Path to a Vaccine • II. The Arrival of the Salk Polio Vaccine: Documents, April-July 1955 • III. Postscript - Polio Prevention after Jonas Salk • IV. Bibliography and Resources • V. Student Assignments • VI. Catalogue of Sources

Section I: Poliomyelitis, Treatment, and Prevention Prior to 1955

B. The Endemic Phase (Antiquity to ~1880)

An endemic disease occurs in every generation, but relatively few individuals are affected because its cause (in this case, poliovirus) comes into equilibrium with the population. The endemic phase of polio lasted from antiquity to the nineteenth century and although poliovirus likely existed in most large communities during this time, the actual disease occurred sporadically and at low levels. With a steady supply of infants, a growing population, and a continually circulating virus, some succumbed to polio, "but the great majority [were] silently infected and thus immunized at an early age."¹ "Immunized" does not mean vaccinated; the infants contracted abortive polio from their environment, prompting their immune systems to recognize the virus and successfully fight future infections.

Surprisingly, during its endemic period, polio incidence was low and the disease went largely unnoticed because of the other serious diseases dominant at the time. Since poliovirus is transmitted via the fecal-oral route, poliovirus regularly circulated in the water supply given substandard hygienic and sanitary practices of the time. Its presence likely meant that infants were immunized early (at a time when they still had some protection from their mother's immune system), thereby protecting them from the disease. One theory argues that when sanitation improved in the 20th century, the virus no longer circulated in the water supply, causing polio to become epidemic without this prior, low-risk exposure to infants.

Egyptian stone carving thought to depict signs of poliomyelitis

While it is challenging to identify with any precision specific diagnoses based solely on written accounts, there are nonetheless several indicators that polio existed in ancient times. Numerous descriptions from biblical or Homeric times depict children with withered limbs, and scientists have found skeletons dating from 4000-2400 BC with bones that look like they may have once been affected by polio.² Particularly interesting is an Egyptian stele (upright stone carving) dating from 1403-1365 BC which depicts a priest with a walking stick and foot deformities characteristic of polio.

The ancient Greek physician Hippocrates (~460-377 BC), the accredited author of the Hippocratic oath, versions of which are still part of contemporary medical education, wrote several accounts of "club foot," a condition that may have been due to polio. He also chronicled an outbreak of a paralytic disease on the Greek island of Thaos.³ After this period through the 17th century, few accounts or records of polio remain.

Though historians have some documentation of the disease in the 17th century, doctors did not accurately describe polio nor note that fever often proceeds paralysis until 1789 when physician Michael Underwood wrote a description of polio in his medical textbook "Treatise on Diseases in Children." Underwood noted that "palsy" attacked children previously reduced by fever, and that paralysis (or muscle weakening) varied in severity. He later added that the disease occurred in adults as well. It is also interesting to note that Underwood found the disease "occurred seldomer in London (i.e. the city) than in other parts (i.e. rural areas)." Later, epidemiologists discovered higher rates of immunity in urban populations because the virus was more likely to circulate there, but it would take centuries before public health officials understood or even recognized Underwood's discovery.

One of the most famous early accounts of polio is Sir Walter Scott's autobiographical description in 1808:

"I showed every sign of health and strength until I was about eighteen months old. One night, I have been often told, I showed great reluctance to be caught and put to bed, and after being chased about the room, was apprehended and consigned to my dormitory with some difficulty. It was the last time I was to show much personal agility. In the morning I was discovered to be affected with the fever which often accompanies the cutting of large teeth [teething]. It held me three days. On the fourth, when they went to bathe me as usual, they discovered that I had lost the power in my right leg."

At the time of Underwood's description and Scott's illness, most doctors did not classify fevers, nor was precise diagnosis common practice. Even after the publication of Underwood's book, it may have been difficult for some doctors to make the connection between a seemingly innocent fever and paralysis, especially since doctors were often called after (what doctors at the time termed) "lameness" set in. In 1840, however, Jacob Heine, a German orthopedist, published a monograph on the disease. Heine reported on 14 cases of polio and made observations, including that the symptoms indicated the disease affected the central nervous system - in particular, the spinal cord.

During the next 40 years, doctors and other observers wrote several accounts of small polio outbreaks, but the disease remained endemic until the 1880s when outbreaks began to gain momentum in Europe.

Living with polio during the endemic phase
Medical treatments for polio varied widely during the endemic phase of the disease. Doctors for the most part did not know what polio was, and they definitely did not know its cause. During the 1800s, physicians suspected foul bowels or teething caused the paralysis. The connection between teething and polio is incorrect but not illogical; many children contracted polio at a very young age, around the same time when teeth first appeared.

Despite so much medical uncertainty, the earliest records of metal braces being used to correct or stabilize the deformities and muscle weakness resulting from paralysis date from Underwood's time. The use of braces to assist polio patients has continued to the present.

Other therapies, less likely to be beneficial, were also tested and employed. Physicians would often bleed patients, create blisters, or use a red-hot iron on the affected limb.⁴ Samuel Gross, a Philadelphia physician, suggested in a lecture in 1872 that doctors rub mercury ointment in "a piece the size of a marrowfat pea twice a day over the entire spine [and]... after bathing, wring the end of the towel out of cold water, and with it strike the entire body, quite smartly, until the skin is reddened."⁵ This technique, "counter-irritation," was used to treat most illnesses at the time.

Accepted treatments changed in 1880 when Doctor William Osler suggested "the child should be in bed and the affected limbs wrapped in cotton... the application of blisters and other forms of counter-irritation is only cruel to the child."⁶ So little was known about polio that this treatment remained remarkably constant for decades.

Continue to Epidemic Emergence (1880-1920)

¹ Paul 11.
² Smallman-Raynor, M R., A D. Cliff, B Trevelyan, C Nettleton, and S Sneddon, eds. A World Geography: Poliomyelitis, Emergence to Eradication. Oxford: Oxford UP, 2006. 65.
³ Smallman-Raynor and Cliff. 68.
⁴ Paul, John R. A History of Poliomyelitis. New Haven: Yale UP, 1971. 64.
⁵ Paul 64.
⁶ Paul 70.