Cholera is an acute diarrhoeal infection caused by the bacterium Vibrio cholera of serogroups O1 or O139. Humans are the only relevant reservoir, even though Vibrios can survive for a long time in coastal waters contaminated by human excreta.
Diphtheria is spread through droplets from coughing or sneezing. Most often the disease causes a sore throat and low grade fever in the first few days of the illness.