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A Product of Good Sanitation? |
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Polio was initially seen as a disease of immigrants in primitive living conditions. Public health officials were obsessed with eradicating filth and enacted strict sanitation policies. But as the 20th century progressed, polio disproportionately struck the middle class, and began striking adults as well as children. Scientists believe this was the result of the improved sanitation. When water supplies were consistently contaminated with the polio virus, as they were in impoverished areas, people were typically infected during infancy, but only rarely developed paralysis -- most suffered little more than diarrhea, and then had lifelong immunity against polio. In contrast, middle-class people with access to clean drinking water might not encounter the virus until later in childhood, when the virus was more likely to spread to brain and spinal cord and cause paralysis.
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| 3-D image of poliovirus. (Image courtesy of David Belnap of Brigham Young University and James Hogle of Harvard Medical School) |
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For decades, no one knew what poliovirus looked like, since viruses cannot be seen under a microscope. In 1985, a team led by James Hogle of Harvard Medical School obtained high-resolution, 3D images of poliovirus, and today, the newly formed Children's Hospital Boston -- Harvard Medical School structural biology unit is heir to the Enders tradition. Led by Stephen Harrison, this group is using a variety of sophisticated tools like X-ray crystallography and molecular electron microscopy to obtain detailed, dynamic, 3D views -- accurate down to the atom -- of how viruses move, transfer information and reconfigure themselves to attack their victims. These images are shedding light on many of today's viral scourges, such as HIV, dengue and rotavirus, and providing new leads for treatment and vaccine development.
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Polio was declared eradicated in the U.S. in 1979. Yet according to the World Health Organization, polio cases worldwide rose by a third in 2004, due in part to vaccine boycotts. Children's and Spaulding Rehabilitation Hospital are still seeing new cases -- the result of international adoptions from Third World countries and from Russia.
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