False-colour scanning electron micrograph (SEM) of the comma- shaped bacterium, Vibrio cholerae, cause of cholera. The bacterium moves by means of a single terminal flagellum (seen here). The spread of cholera is associated with poor sanitation and water supplies contaminated by faeces from a patient. The bacteria lodge primarily in the small intestines causing inflammation, vomiting, diarrhoea and ultimately dehydration. Magnification: x6500 at 6x4.5cm size.