Medicine: Polio at Work

Doctors have long believed that the polio virus creeps along the nerves, on its way to destroying the nerve cells. Last week, for the first time, the virus was caught in the act. Drs. Eduard De Rober-tis and Francis Otto Schmidt of M.I.T. showed a Toronto convention of the Electron Microscope Society of America some remarkable pictures of the polio virus marching in orderly files along a nerve fiber.

The sight was cheering medical news to every polio fighter. Said one doctor: “Once we can see a thing, we can study it; and when we know how it operates, we are usually able to stop the operation.”

Last year Drs. De Robertis & Schmidt turned their electron microscope, which is far sharper-sighted than the ordinary “light microscope,” on nerve fibers, the delicate tendrils sent out by nerve cells. They found that the fibers were cables made up of many hollow tubes about one-millionth of an inch in diameter. The discovery gave them an idea. The “neuro-tubules” seemed ideally adapted for conducting submicroscopic objects around the body. Perhaps, thought the doctors, they conducted the polio virus on its missions of paralysis and death.

This theory turned out to be true. The doctors proved it conclusively by exposing cut nerve ends of Rhesus monkeys to the virus of human polio. They then separated the slender neurotubules a little way up the nerve and examined them under the electron microscope. Some of them were full of tiny round specks not present in healthy nerves. By extracting the nerve samples at different times, the doctors proved that the particles crept slowly up the nerve from the point of entry. They moved about 2 mm. (1/12 inch) an hour—roughly the rate that polio infection is known to advance along nerves.

Besides providing a starting point for the understanding of how polio gets around, the new technique of watching the virus at its dirty work may help in early diagnosis—a very important matter.