March 18, 2010, Updated September 24, 2012

Sharing water bottles and drinking cups increases the likelihood of being infected with the bacteria that most commonly causes acute pneumonia, according to a recent study of Israel Defense Forces (IDF) soldiers.

The IDF joined infectious disease experts to examine the proliferation of the bacteria over seven months among 149 combat soldiers in training and drill courses. Before arriving for training, less than one-tenth of the individuals carried the bacteria. After completing their courses, however, over a third was found to be infected.

The researchers determined that infection often occurs through an exchange of saliva, in contradiction to the theory that the bacteria are transmitted primarily through the respiratory system. Drinking from the same cup or bottle as others, they found, raised the risk of infection by 63 percent.

The researchers concluded that the soldiers who shared their cups or bottles were 2.4 times more likely to be infected by the bacteria that cause pneumonia. The month with the greatest risk of infection, they found, is March, followed by August and November.

The findings were presented at the Seventh International Symposium on Pneumococci and Pneumococcal Diseases, held this week in Tel Aviv with the participation of more than 1,000 physicians from 68 countries.

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