Cholera

Cholera is an infectious disease characterized by large volumes of diarrhea and subsequent dehydration. In 2006, almost 132,000 cases were reported to the World Health Organization, resulting in 2272 deaths. These numbers represent a 30% increase over the 2004 statistics. The continent of Africa appears to be the hardest hit, accounting for 58% of all cases worldwide. While cholera has been recorded in history for over 2000 years, it is only within the last approximately 150 years that doctors and scientists have gained an understanding of the causative agent, mode of transmission, and means of treatment and prevention.

Typically found in saltwater, Vibrio cholerae are curved, gram-negative rods. These rods may link together from end to end to form S shapes or spirals. This organism possesses a polar flagellum and is thus very motile. It also possesses long, filamentous pili, called Tcp pili, which form bundles on the surface of bacterium. Since the bacterium is not very acid tolerant, it grows best under alkaline conditions, such as those with a pH ranging from 8.0 to 9. In addition, while it is facultatively anaerobic, it will grow best under aerobic conditions. Vibrio cholerae may be grown in a variety of media. While routine media, such as blood agar or MacConkey agar is sufficient, using thiosulfate-citrate-bile salt-sucrose agar enhances isolation of the organism.

The recorded history of cholera may extend back almost 2,500 years with ancient Sanskrit texts found in India describing a severe illness with similar characteristics. This disease remained in the country of India for many years, not spreading to Europe and the Americans until the early 1800s. Since then, a number of global pandemics have occurred causing great illness and even death.

1. The first pandemic occurred in 1817 as cholera spread outside of India along trade routes to the west and into southern Russia (Sack, Sack, Nair, & Siddique, 2004).
   
2. The second pandemic originated in New York in 1832, spreading quickly to Philadelphia in only two weeks and then down the coast to the Gulf of Mexico.
3. Seventeen years later, in 1849, London became part of the pandemic as well. By the end of this 19-year pandemic, scientists had realized that a correlation existed between the disease and where it spread, and related sources of public water.

Several years later, John Snow, a London doctor, published a paper correctly identifying the route of disease transmission as the fecal-oral route.

Cholera remains a major global problem. However, as science advances and individuals are made aware of preventative measures, the fight to eliminate this disease could be won in the not too distant future.