Thumbnail: Scanning electron microscope image of Vibrio cholerae bacteria, which infect the digestive system. Image used with permission (Public Domain; T.J. Kirn, M.J. Lafferty, C.M.P Sandoe and R.K....Thumbnail: Scanning electron microscope image of Vibrio cholerae bacteria, which infect the digestive system. Image used with permission (Public Domain; T.J. Kirn, M.J. Lafferty, C.M.P Sandoe and R.K. Taylor).