If there is anything worse than the mucky, dreary, icy weather of winter, it is the sniffly, stuffy, achy congestion of a winter cold, an internal misery so perfectly in tune with the misery outside that no one has to wonder where a cold in the nose got its name.
Nor is it any wonder that medical folklore has forged a stubborn link between the two: catch a chill and you'll catch a cold, common wisdom runs, especially if you are rash enough to wander around in the cold with damp hair or wet feet.
A survey of the medical literature shows that for more than a century, scientists have invested an extraordinary amount of time and energy in debunking this old saw, with the aid of a small army of shivering, sneezing volunteers. But despite their efforts, the link between colds and the weather still lingers and continues to inspire yet more research.
''Health and the weather was a big topic in previous periods of history,'' said Dr. Jack M. Gwaltney Jr., an emeritus professor of medicine at the University of Virginia and one of the world's leading experts on the common cold. Many infectious diseases cycle with the seasons, Dr. Gwaltney said, and doctors still seldom understand why.
Continue reading the main storyColds, of course, are caused by any of several hundred different strains of virus. People get more colds in the winter at least in part because nasty weather drives them indoors to make extremely close contact with one another's infectious mucus.
But the story is more complicated than that, as a century of experiments shows.
The link between chills and infection dates from Louis Pasteur, who found in 1878 that chickens are naturally immune to anthrax. He guessed that their high body temperatures might be responsible (normal chicken temperature varies from 104 to 107) and decided to expose a chicken to anthrax and then chill it in a basin of water. The chicken developed anthrax and died. Pasteur repeated the experiment with a chicken he fished out of the water after a few hours and warmed in a blanket. That chicken became sick but recovered.
Generations of experimental biologists replicated Pasteur's experiments with other animals and other germs, and confirmed that chilled monkeys were more susceptible to polio, and chilled mice and rabbits were more likely to succumb to pneumonia and a variety of other respiratory infections.
Meanwhile, other scientists began to look for similar tendencies in chilled humans.
A German scientist studying thousands of soldiers during World War I reported that those stationed in cold, wet trenches for 72 hours were four times as likely to develop colds as those kept in their barracks. Young women in college studied in the 1940's reported colds more frequently during cold rainy periods than cold sunny days. Mounties in the Canadian Arctic developed more colds and more severe colds during periods of unusual exertion in cold day and night conditions.
But scientists also found the reverse. On a tiny frigid island in the Arctic Sea studied in the 1930's, for instance, no inhabitant caught cold during the winter. It was only after the ice broke and the first ship bringing provisions docked in May that the islanders got sick, presumably from infected sailors.
Experimenters soon stopped chilling animals in the laboratory and began chilling people instead. In the years after World War II, thousands of volunteers thronged to the Common Cold Research Unit in Salisbury, England, where they were paid for allowing researchers to drip a little infected mucus into their noses.
Among the volunteers were 12 people who were assigned to bathe and then wander around cold corridors in wet socks and bathing suits ''for half an hour or as long as they could bear it,'' the chief researcher wrote in a report.
''Most showed a drop of several degrees in body temperature and felt rather chilly and unhappy for a time,'' he reported, but whether or not they were exposed to infected mucus, they were no more likely to catch cold than their warmer colleagues.
In the 1950's, Chicago researchers repeated the experiment on a larger scale with several hundred volunteers sitting in their socks and underwear in a 60-degree room before being inoculated with infectious mucus. Others, in coats, hats and gloves, spent two hours in a large freezer. The conclusion: all 253 chilled volunteers caught cold at exactly the same rate as 175 members of a warm control group.
The discovery of the rhinovirus, the most common cause of the common cold, inspired Texas researchers to readdress the question. In 1968, they reported that they had chilled 27 men in a cold room or a cold bath, then dripped a strain of rhinovirus in their noses at various times afterward. Some were chilled after they had actually developed a cold, to see whether it lingered longer.
Chilling had no effect on the chances of catching a cold or the severity of colds caught. Enough is enough, these researchers said at the end of their report. ''Further studies seem unwarranted.''
But the studies have continued nonetheless.
Many experiments have tried to assess the effects of the cold on immune function. Animals kept in profound cold have somewhat dampened immune systems, but researchers disagree on whether this is an effect of the cold itself or a stress response to a frightening and unpleasant experience. In 1999, Canadian researchers found exactly the opposite effect in humans: exposure to the cold seemed to stimulate many separate facets of the immune system in healthy young men spending two hours in the equivalent of a large refrigerator.
Meanwhile, virologists have learned that the common cold is a complex entity -- not a single disease at all, but many similar ones, and that all of them cycle in response to the weather in ways that are still not understood. It turns out that rhinoviruses cause colds mostly in the spring and the fall. Other families of viruses cause most winter colds. Among them is the influenza virus, which causes colds as well as the flu, but is too dangerous to use in human experiments to figure out why.
Dr. Gwaltney, the cold expert, suggests that it is not temperature but humidity that fosters many colds. The rhinovirus thrives in humidity, and his research in the 1970's showed that peak rhinovirus seasons correlate with runs of overcast, wet spring and fall days that keep children inside to infect their elders while allowing the virus enough humidity to thrive.
''Climate has both biological and behavioral consequences,'' Dr. Gwaltney said. ''There are plenty of experiments left to do.''
Years ago, a group of cold researchers identified the poker game as the ideal setting for studying cold transmission. Poker players clustered around a table are virtually encased in the invisible infectious spray generated by coughs, sneezes and excited conversation, they handle the same chips and cards over and over again, often touch fingers, and stay in their seats for hours.
Cold researchers have already thrown a series of 12-hour poker parties for sniffling cold victims and healthy volunteers. In some of them, the guests played poker wearing large plastic collars, similar to the ones dogs wear after surgery, to see if preventing people from touching their noses might decrease viral transmission. (Just as many became sick.)
It may be only a matter of time before new armies of volunteers are invited to poker parties held in the back of a meat locker, just to settle the matter of colds and the cold definitively, once and for all.
In the meantime, it does not hurt to bundle up.
Continue reading the main story
