Polio: An era not quite over
Fifty years ago, the nation was gripped by the terror of polio, an infectious disease causing paralysis and atrophy of skeletal muscles, often resulting in permanent disability and deformity. In the heat of the summer, beaches were closed since the highly contagious disease often spread through water. The children and adults who fell ill saw their lives become a nightmare of spinal taps, orthopaedic surgeries and braces, social isolation and the threat of being confined to an iron lung in order to breathe.
In this, the 50th anniversary of the development of the polio vaccine by Jonas Salk, Dream Magazine looks back on the epidemic—and Children's Hospital Boston's role in stopping it.
The very year the Salk vaccine was announced, the state of Massachusetts suffered the worst polio epidemic in its history. Children's was at the epicenter, caring for so many children and adults that the line of cars filled with panicked families stretched for several blocks away from the hospital.
Rehabilitation in tubs and pools enabled patients to move and strengthen weakened limbs. Several orthopaedic operations were pioneered or perfected at Children's, preventing children from developing permanent limb deformities or allowing them to discard their braces.
Viruses are too small to be seen under a microscope, so for decades, no one knew what poliovirus looked like. In 1985, a team led by James Hogle, PhD, of Harvard Medical School obtained high-resolution 3-D images of poliovirus with X-ray crystallography. The more recent image above shows poliovirus attached to multiple receptors—60 to be exact—from the surface of an intestinal cell. The multiple attachments give the virus a tight grip. This and other images offer scientists an unprecedented glimpse into how polio invades human cells.
While Jonas Salk is credited with developing the polio vaccine, an essential precursor was finding a practical way to grow the polio virus in quantity in the lab—a discovery that earned Children's scientists John Enders, PhD (left), Thomas Weller, MD, and Frederick Robbins, MD, a Nobel Prize in 1954. With this breakthrough, reported in 1949, scientists could culture the elusive virus in a variety of cell types. Previously, the polio virus could only be grown in nerve tissue, which is difficult to maintain, or in live animals. Researchers would have to infect an animal with polio and try to deduce information about the virus, a laborious technique.
The iron lung was the first effective treatment for patients so severely paralyzed by polio that they couldn't breathe. The first model consisted of a tank and a pair of vacuum cleaner blowers, and in 1928, an 8-year-old girl at Children's became the first person to use an iron lung. Because patients lived inside the respirators for weeks, months or even years at a time, later models had portholes through which clinicians could give care. The respirator shown here was used in the early 1930s.
As immunization with the Salk vaccine got underway (Salk administers a dose, above), the polio epidemics came to a halt, and in 1979, the disease was declared eradicated in the U.S.
But the polio story isn't over. Some 70 percent of survivors now suffer from postpolio
syndrome, or weakness in previously unaffected muscles. Worldwide, new polio cases actually rose by one-third in 2004, in part because of a vaccine boycott in Africa. And Children's still sees new cases—the result of international adoptions from developing countries and Russia.
Today, scientists at Children's continue to seek basic knowledge about viruses that can be turned into vaccine and drug strategies, aided by modern tools like X-ray crystallography. In February 2005, the Laboratory of Molecular Medicine published a report describing how a key part of the human immunodeficiency virus (HIV) changes shape, triggering other changes that allow the AIDS virus to enter and infect cells. These insights could lead to novel interventions that block the shape change.