Illustration of the bacteria Bordetella pertussis. Individual bacterium are shown as pink rod shapes. Bordetella pertussis is unable to survive outside the body, therefore humans are the only known reservoir of the bacteria. Infection of the epithelial cells of the lungs causes whooping cough (also known as pertussis). The symptoms arise because a toxin in the bacteria disables the cilia on the epithelial cells so they cannot remove debris from the lungs. The resulting coughing can expel bacteria causing infection in other people.