After more than a decade of work, an increasing body of scientific evidence suggests that the many viruses that cause the common cold are spread chiefly by hand contamination rather than by coughing or sneezing, researchers said yesterday.
Teams from the University of Virginia and the University of Wisconsin reported on studies showing that a new chemically treated version of Kleenex is highly effective in stopping the spread of the most common illness by killing cold viruses before they get on the hands.
But, the Virginia research also shows that a less costly, old-fashioned approach -- wiping one's nose frequently with regular facial tissue and keeping one's hands clean -- may be about as effective.
A cold sufferer may contaminate his hands while blowing his nose or sneezing and then transfer the hardy organisms by touching others or by touching household objects where the viruses may live for hours or days.
The strongest proponent of a new "viricidal" or virus-killing tissue is its pioneer, Dr. Elliot C. Dick, a University of Wisconsin researcher who reported yesterday to an infectious-diseases meeting here that the tissue has proved 100 percent effective in stopping the spread of cold viruses under experimental conditions.
In his tests, in which student volunteers purposely infected with terrible colds played poker with healthy men for 12-hour stretches, the new tissue far surpassed the performance of the cotton handkerchiefs carried by generations of cold-sufferers.
Dick, who began testing the idea in Antarctica in the 1970s, said that in two recent tests with the virus-killing tissue, none of the 24 healthy volunteers got sick. But in the cotton-hanky trial, 58 percent -- 14 out of 24 -- of the people who were exposed to a cold caught one.
He said a single square inch of the specially treated 3-ply tissue can destroy 100,000 virus particles in one minute -- or about 80 percent of the viruses present. The tissue is impregnated with three compounds -- citric and malic acids, found in fruits, and sodium lauryl sulfate, used in toothpaste -- that are considered nontoxic to humans but deadly to "rhinoviruses," a group of more than 100 cold viruses.
In a separate experiment at the University of Virginia, Drs. J. Owen Hendley and Jack Gwaltney Jr. also found that the chemically treated tissue was highly effective, with none of 24 exposed research subjects developing a cold if the sufferers used the tissue.
But Hendley found to his surprise that the "control" tissue, regular tissue without any special treatment, was also quite effective. Only three of the 25 persons who were exposed to cold sufferers who frequently used regular tissue became infected. But if cold sufferers used no tissue at all, about half of the the people they exposed to the viruses got sick.
Hendley noted that it has been difficult to prove exactly how colds spread, but he and his colleagues have concluded that the most likely route is through the hands of a cold sufferer touching infected nostrils where the viruses are concentrated.
Hendley says his studies found through direct observation of a crowd of medical professionals for an hour in a large lecture hall that one of three people would pick or rub their noses in such a way that viruses would be transmitted if they had a cold. "I was stunned," he said with a smile. "Imagine what happens with kids."
While other Virginia experiments supported this hand-transmission route, he was surprised to find that it was difficult to catch a cold by breathing in cold viruses spread into the air by a cough or sneeze.
Hendley and Dick presented their findings at the 24th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
Their work with the new virus-killing tissue has been conducted under the auspices of Kimberly-Clark Corp., makers of Kleenex, which is beginning test marketing of the product in upper New York state.
Called Avert, it is expected to be marketed in a blue-and-white carton of 60 tissues at a cost of about $1.30, about twice the price of regular tissues, says company representative Russell Carpenter.