Vibrio cholerae is a comma-shaped, gram-negative bacteria that can cause the acute diarrheal disease cholera in humans. It has a single, polar flagellum that allows it to move. V. cholerae typically infects the small intestine and produces a toxin that causes the severe watery diarrhea characteristic of cholera. While it usually spreads between humans, V. cholerae can also live in brackish coastal and river waters, and some research has suggested certain arthropods may act as hosts in the environment.