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What role may the weather play in the spread of H1N1? meteorologists have uncovered possible important roles the weather may play in the spread of H1N1, formerly known as the swine flu.

An El Nino is forecast by to develop this summer. El Nino produces warmer-than-normal Pacific Ocean water temperatures off of Central and South America. This warm ocean current alters the weather pattern in the United States and abroad. The pattern could last through the coming winter.

During a typical El Nino winter, the southern part of the United States experiences cooler- and wetter-than-average conditions, while the northern part of the nation experiences somewhat milder conditions with less snow, compared to average.

Common influenza outbreaks have flourished during the winter months when the air is generally cold and dry. There has been some evidence suggesting that influenza can survive outside the body longer under cold, dry conditions. A recent study done by Oregon State University indicated that low humidity of air alone could be a determining factor.

The study suggested that year-round low humidity, such as that of the western U.S. could harbor common influenza throughout the year.

Indoor humidity levels can drop very low, especially in the winter months, even if you keep your house cool. This occurs when, for example, air at 20 degrees with a humidity of 50 percent is then warmed to 70 degrees. The humidity level can drop to 10 to 20 percent. Your house can still be very dry even during a rain or snowstorm in January.

It is not known whether the H1N1 virus or other forms of influenza survive in the air by itself, or via transport of moisture droplets. Strong, very dangerous strains such as H1N1 have been known to ignore the trends of common influenza.

Regardless of whether the upcoming winter in the southern hemisphere, or the distant winter in the northern hemisphere is mild or harsh, winter months typically have more people indoors in colder climates. That can increase exposure to others who are ill.

According to a report released Friday by the World Health Organization, more than 3,100 cases of H1N1 have been confirmed in a total of 28 countries. That includes more than 1,100 in Mexico, at least 1,639 in the United States and 214 in Canada.