Introduction to Epidemiology 6th Edition by Ray M Merrill

Exercise 14

From Figure 1, what is the index case?What date is the beginning of the epidemic?What other time factors are discerned fromthis chart? How did Snow establish the time of onset?

Figure 1 The dates and numbers of attacks of cholera in the Broad Street pump cholera epidemic, London.

Step 1 of 4

Cholera is contagious disease that is caused by various strains of Vibrio cholerae. V.cholerae is comma shaped gram negative bacteria. It releases endotoxins once it enters the alimentary canal. These endotoxins, also called as the cholera toxins are the main cause of diarrhea, vomiting and spams. These toxins draw water from the blood capillaries that result in the excretion of watery stools. The water and electrolyte balance of body is lost. The patient must be given ORS (oral rehydration Solution) to restore the electrolyte and water balance of the body.

The most horrific cholera outbreak took place in Broad Street, London, in the year 1854.

People who consumed water from the common pump were attacked by cholera. People residing in adjacent regions were also attacked by cholera. The deceased were reported to have consumed water from Broad Street in one form the other. Many local coffee shops used the pump water and served it at dinner time.