Study Looks at Pneumonia After Flu

A study using mice offers some new clues about the pneumonia infections that often occur after flu. These second infections greatly increase the risk of death. First, researchers injected mice with flu virus. Later, they injected Haemophilus influenzae bacteria. These bacteria are a common cause of pneumonia. Mice were most likely to die if they were injected with the bacteria soon after the flu virus. Pneumonia quickly caused severe damage to the lungs. This damage often led to death. This happened in mice with both normal and weak immune systems. The study appeared January 22 in The American Journal of Pathology.