Haiti’s cholera strain came from South Asia: StudyDecember 11th, 2010 - 2:29 pm ICT by ANI
London, Dec 11 (ANI): Scientists, who did a rapid genetic analysis of bacteria collected from Haitian patients, have concluded that the strain of cholera currently sweeping through post-earthquake Haiti originated in South Asia.
The finding supports the notion that the cholera bacteria fueling the outbreak arrived on the island via recent visitors.
“The mostly likely explanation for the sudden appearance of cholera in Haiti is transmission of V. cholera by an infected human, food, or other contaminated item from a region outside of Latin America to Haiti,” concluded Howard Hughes Medical Institute (HHMI) investigator Matthew Waldor and co-authors.
While cholera is endemic in many parts of the world, including regions of Latin America, until October, Haiti had historically been spared from the intestinal disease. But in mid-October, an outbreak flared in northern Haiti and quickly swept across the country. By December 3, the bacteria had sickened more than 93,000 people, killing some 2,100. The World Health Organization anticipates that the outbreak will last a year or longer.
“The scientific question for us was, ‘How did cholera come to Haiti?’ It hadn’t been there for more than a hundred years,” said Waldor, a microbiologist and infectious disease specialist whose laboratory at Brigham and Women’s Hospital studies cholera and other pathogenic gut bacteria.
Waldor obtained two samples of Vibrio cholerae, the bacterium that causes cholera, from two Harvard Medical School colleagues, Stephen Calderwood and Jason Harris, who traveled to Haiti in November to assess the outbreak. Waldor then established a collaboration with Pacific Biosciences, which manufactures powerful DNA sequencing machines that can rapidly scan and identify millions of bases of genetic material.
A team of scientists there, led by Eric Schadt, sequenced the complete genomes of the cholera bacteria in the samples. Waldor received the V. cholera samples on November 8 and had the bacterial DNA sequence from Pacific Biosciences in hand by November 12.
The DNA readout showed that the two Haitian strains of V. cholera - isolated from different patients - were essentially identical, supporting the idea of a single origin of the nation-wide outbreak. The two strains were also essentially identical to three other Haitian outbreak samples that had been sequenced (but not analyzed) by the Centers for Disease Control and Prevention (CDC).
The HHMI, Harvard, and Pacific Biosciences team then compared the genome of the Haitian strain to the genomes of 23 other V. cholera strains from various parts of the world that were stored in the genetic data repository GenBank.
Surprisingly, the Haiti strain bore the strongest resemblance to strains that are currently circulating in South Asia. Conversely, the Haitian strains differed significantly from the bacteria currently circulating in Latin America. Some cholera experts had suggested that endemic Latin American V. cholera - found in Peru and elsewhere - was the most likely source of the Haitian outbreak.
“The big conclusion is that the Haiti cholera epidemic is caused by a strain that was most likely introduced into Haiti from South Asia, and not from some strain that washed up environmentally from Latin America,” Waldor said.
The findings have been reported in the New England Journal of Medicine (NEJM). (ANI)
- Cholera bacteria in Haiti similar to Southeast Asian variety - Nov 03, 2010
- New E. Coli bacteria resistant to eight classes of antibiotics - Jun 04, 2011
- Haiti cholera toll rises to 1,721 - Nov 30, 2010
- Google GPS, gene sequencing combo tracks typhoid outbreaks - Oct 17, 2011
- DNA sequencing tracks details of TB outbreak - Sep 04, 2012
- Full genetic blueprint of multiple prostate tumors unveiled - Feb 10, 2011
- Haiti cholera deaths top 1,500 - Nov 26, 2010
- Aid for Haiti a priority as 600,000 still live in camps following quake - Oct 06, 2011
- Ghana cholera toll rises to 21 - Apr 19, 2012
- Haiti cholera toll goes up to 724 - Nov 12, 2010
- Harvard team crack superbugs' genetic code - May 23, 2012
- Scientists sequence genomes of lyme disease bacteria - Oct 19, 2010
- First genomic collection of human microbes published - May 21, 2010
- UN deplores violent acts in Haiti - Nov 17, 2010
- Haiti cholera deaths reach 330 - Oct 30, 2010
Tags: cholera bacteria, dna sequencing, gut bacteria, harvard medical school, hhmi investigator, howard hughes medical, howard hughes medical institute, hughes medical institute, infectious disease specialist, jason harris, northern haiti, pacific biosciences, recent visitors, s hospital, school colleagues, stephen calderwood, sudden appearance, vibrio cholerae, waldor, world health organization