Vibrio cholerae. Illustration of three bacteria of the type Vibrio cholerae, cause of cholera in humans. These rod-shaped Gram-negative bacteria occur in colonies. Each bacterium moves by means of a hair-like, polar flagellum. Here, seen within the bacteria is genetic nucleic acid material (yellow) which lies freely in the cell. Cholera is an acute infection of the small intestines causing vomiting and diarrhoea leading to potentially fatal dehydration. The bacterium is a water-borne pathogen, transmitted to humans through drinking water contaminated by human or animal faeces. Outbreaks of cholera are linked to poor sanitation Magnification: approx. x30,000 at 5x7cm size.