Finally, there is scientific confirmation of what the world has always known. Researchers have confirmed that cold temperatures do trigger off the cold, that is, the most common global infection marked by runny noses, sniffles and sneezes.
A team from Yale scientists found that cold temperatures dampen the body’s natural defenses against a rhinovirus, the leading cause of seasonal colds, the scientific journal Nature has reported. Their experiments were done on mice and artificially grown human cells from respiratory tract.
“What we show here is a temperature-dependent interaction between the host and the virus,” says team leader Ellen Foxman, according to Nature. The research findings were presented at an American Society of Microbiology conference in Denver, Colorado.
Although it is well established that colds are more common in autumn and winter, when temperatures are lower, but efforts to link the rhinovirus to temperature fluctuations have not succeeded. Some studies have shown that exposure to cold temperature will spark off the sneezing and sniffles, while others could not find any connection.
There are over 200 viruses that can cause the common cold. The rhinovirus is responsible for 30 to 50 percent of cases. But scientists have discovered more than 100 types of rhinoviruses, according to the National Institute of Allergy and Infectious Diseases, affiliated to the US government’s National Institutes of Health.
What is new in the Yale study is that for the first time an explanation has been given for the link between colder temperatures and virus activity. Foxman and her colleagues discovered that at warmer temperatures mice infected with the rhinovirus produced a burst of antiviral immune signals, which activated natural defenses that fought off the virus, Nature reported. But at cooler temperatures, the mice produced fewer antiviral signals and the infection could persist.
Experimenting with human airway cells in the lab under cold and warm conditions the researchers infected them with rhinovirus. They found the warm infected cells were more likely to undergo programmed cell death – cell suicide brought on by immune responses aimed at limiting the spread of infections – than the cold-infected cells, Nature reported.
So, the explanation for getting cold more in winters is that as humans breathe in the colder air which chills the upper airways and sets the table for the rhinoviruses to start getting active.
Nature quoted virologist Vincent Racaniello of Columbia University as saying that temperature is probably just one of several factors that explain how rhinoviruses spread. “Simple answers like this are never the whole story,” he told Nature.
Source: The Times of India