They Get Stronger While Inside

The NADC scientists were watching a specific type of a dangerous microbe—one that causes an illness called Salmonella poisoning. Not only did this bacterium survive after being taken in by a protozoa, it became especially strong and hard to kill. This was the first time that researchers anywhere had seen bacteria that cause disease get stronger from their interaction with protozoa inside of animals.

“We’ve known for a long time that protozoa are in cattle,” says Rasmussen, a microbiologist. “Protozoa benefit the cow and assist it with digestion." He says protozoa had never before been thought of as organisms in which dangerous microbes could live and multiply.

And there's more bad news! Rasmussen says that the scientists found that there’s something about being inside the protozoa that turns on certain defenses in the Salmonella bacteria that they can use to cause infections later on.