Researchers at Washington University in St. Louis might have discovered by the West Nile virus strikes the elderly harder than it does other people. Most people infected with the virus have only mild symptoms. Yet, the Centers for Disease Control and Prevention, reports more than 250 deaths nationwide from West Nile. Most of the people who died were over 60 years old. Researchers have found that mice that lack a certain immune cell always got sick when infected with West Nile. Mice react much the same way humans do to West Nile. The next step for the scientists is to do human testing.