New Delhi: "Small children and the elderly tend to succumb more to respiratory infections in winter as viruses multiply faster in cold temperatures. Very cold weather, combined with fog, like the capital has been witnessing for the past week, is 'ideal' for certain viruses to spread that cause influenza type infections" say doctors. 

"The elderly and children are prone to the ill effects of low temperature. The influenza infection rates are higher during extreme cold, because these viruses multiply faster in cold temperature," said a senior official of the Indian Council of Medical Research, who declined to be named.

The virus infections tend to infect children between one-and-a-half to five years age, said Sisir Paul, a paediatrician with Max Super Speciality Hospital, Saket, in south Delhi.

"In this cold weather we have seen a 25 percent rise in upper respiratory tract infections," Paul told sources.

 Older children and adults do not get such infections easily as they have developed the antibodies in themselves from previous infections.

 Once we get an infection, we develop immunity to it," he said.
 

According to Paul, there were not many cases yet of broncholitis, an infection of the lower respiratory tract, which also occurs in severe winter months. "A few cases of broncholitis have come. It comes on more when there is heavy fog and no sun. The virus cannot multiply when there is good sunlight."

However, the other diseases that plague children like jaundice, typhoid and gastroenteritis are less as those viruses don't multiply in winter.

According to P.K. Mukherjee, a senior private physician, a major reason for many people catching influenza is from exposure.

"The virus spreads from one to the other in public places. The elderly are more prone to catching infections as they have low resistance," he said.

 "In the elderly, their metabolism slows down and the virus is able to spread faster," said Mukherjee, adding that the most common infections during the cold weather were pneumonitis and sinusitis

"The room heater is not recommended at all," said Mukherjee, adding that the sudden change in body temperature caused when a person leaves a room artificially warmed to the cold outside also leads to illnesses.