<prompt> Which has an incubation period of less than a week: March 2010CholeraMeaslesFilariaKala-azar  <response>: Ans. A: Cholera Cholera is an acute diarrhoeal infection caused by ingestion of the bacterium Vibrio cholerae. Transmission occurs through direct faecal-oral contamination or through ingestion of contaminated water and food. The disease is characterized in its most severe form by a sudden onset of acute watery diarrhoea that can lead to death by severe dehydration and kidney failure. The extremely sho incubation period - two hours to five days - enhances the potentially explosive pattern of outbreaks, as the number of cases can rise very quickly. About 75 of people infected with cholera do not develop any symptoms. However, the pathogens stay in their faeces for 7 to 14 days and are shed back into the environment, potentially infecting other individuals. Cholera is an extremely virulent disease that affects both children and adults. 