On the quiet London street corner of Broadwick and Lexington stands the John Snow pub with a commemorative plaque honoring the medical detective work of Mr. Snow, who identified the Broad Street water pump as being responsible for an outbreak of cholera that ravaged thousands in 1855.  Today, all patrons of the John Snow can enjoy a pint of local ale, and even more importantly, a refreshing glass of crystal clear, pathogen-free water. It was John Snow who first discovered that cholera, the most feared diarrhea-associated illness in the world, was conveyed by water.

Cholera is caused by the bacteria Vibrio cholera, a powerful pathogen. Untreated cases can lead to dehydration and death within hours of infection.  Cholera is most commonly acquired from drinking water in which the bacteria is found naturally or into which it has been introduced from the feces of an infected person.  The disease can also be acquired from contaminated fish, shellfish or vegetables that have been rinsed with contaminated water.

Cholera outbreaks occur yearly in developing countries.  In 2007, 53 countries reported 177,963 cholera cases and over 4,000 deaths to the World Health Organization Last month, the worst cholera epidemic in almost twenty years broke out in Nigeria.  Nearly 800 people have died, and the epidemic is now spreading to the neighboring countries of Cameroon, Chad and Niger where hundreds of others have succumbed to the illness.

Further east, monsoon flooding that has displaced 18 million people in Pakistan has raised fears of a massive cholera outbreak. Next door, India reports almost seven hundred patients from the state of Orissa have been treated for cholera. Thirty nine patients have been reported dead, and local official N.B. Jawala reports that over 50 new patients are being seen daily with severe symptoms.  ‘We are struggling to prevent the disease from spreading,” he added, “but the patients do not come to the hospital for treatment.”  Indeed, since cholera infection is most often asymptomatic or results in only mild symptoms, the management of a cholera outbreak can be an epidemiologist’s nightmare.  

Travelers who follow tourist itineraries and who observe food safety recommendations are at very low risk. The risk, however, is real for those who drink untreated water or eat poorly cooked or raw seafood in cholera-endemic areas, primarily sub-Saharan Africa, India and China.  Those travelling to developing countries where access to good medical care (intravenous fluid and electrolytes) is limited are at the greatest risk of acquiring and succumbing to the illness. There is no vaccine for cholera available in the United States, and the CDC does not recommend either of the two vaccines available outside the United States because of the low risk of cholera to U.S. travelers and the brief and incomplete immunity that the vaccines confer. Without any medical silver bullets at hand, it appears that this ancient illness is not going away anytime in the near future.

Photo by ell brown.