Cholera, an acute diarrheal illness caused by bacterial infection, annually sickens 3 to 5 million people and results in 100,000 deaths. Beginning in late 2010, Haiti experienced a severe cholera outbreak for the first time in more than a century. To identify the evolutionary origin and virulence of the organism responsible, NIAID-funded researchers used advanced DNA sequencing technology to rapidly sequence the complete genomes of five strains, or subtypes, of Vibrio cholerae, the bacterium that causes the disease.
The scientists sequenced two strains of bacteria that were isolated from cholera-sickened Haitian patients, one strain that caused cholera in Latin America in 1991, and two strains that were isolated in South Asia in 2002 and 2008. They then compared these sequences with those of 23 diverse strains that had been previously obtained.
The researchers found that the strains isolated from Haitian patients resembled a form of V. cholerae identified in Bangladesh in 2002 and 2008 that was associated with severe disease, drug resistance, and the ability to persist in the environment. By contrast, the Haitian strains were much less related to strains circulating in South America.
The scientists concluded that the cholera strain behind the Haitian outbreak was likely of distant geographic heritage, and not of local, Caribbean, Gulf of Mexico, or Latin American origin. They theorized that the Haitian strain was introduced through human activity and warned that it threatened the entire region, emphasizing the need for immediate and effective public health interventions and vaccination to stem a wider epidemic.
Reference: Chin CS, Sorenson J, Harris JB, Robins WP, Charles RC, Jean-Charles RR, Bullard J, Webster DR, Kasarskis A, Peluso P, Paxinos EE, Yamaichi Y, Calderwood SB, Mekalanos JJ, Schadt EE, Waldor MK. The origin of the Haitian cholera outbreak strain. N Engl J Med. 2011 Jan 6;364(1):33-42.
Last Updated January 08, 2013
Last Reviewed January 08, 2013