Scientists sequence genome of cholera bacteria

WASHINGTON (CNN) -- Researchers have sequenced the genome of the bacteria that causes cholera, a potentially fatal intestinal infection common in developing countries.

The scientific achievement, to be published Thursday in the journal Nature, is expected to help experts develop better treatments and possibly a more effective cholera vaccine.

"Determining the genomic sequence of medically important pathogens such as Vibrio Cholera holds enormous promise for helping us fight some of the world's most intractable infectious diseases," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), which funded the project. NIAID is a component of the National Institutes of Health.

	RESOURCES
What travelers need to know about cholera from the Centers for Disease Control and Prevention

Cholera, which causes diarrhea and can lead to dehydration and death if left untreated, is prevalent in many of the world's developing areas. In 1991 it struck Latin America, where it had been absent for more than a century. Within the year it spread to 11 countries, and subsequently throughout the continent. Cholera cases were found in 1970 in West Africa, which had not seen the disease for more than 100 years; the disease quickly spread to a number of African countries and eventually became common in most of the continent.

Cholera is especially problematic in developing countries where water supplies, sanitation, food safety and hygiene practices are often inadequate.

Most episodes are mild and are treated by rehydration, but extreme cases can lead to death through dehydration within hours.

A person can become infected by consuming water or food contaminated by the bacterium. Common sources of infection are raw or undercooked seafood, raw fruit and vegetables, and other foods that have been contaminated during preparation or storage.

Researchers from the Institute for Genomic Research were interested to find that cholera has two active chromosomes -- one smaller than the other -- unlike most bacteria, which have only one. "It makes us think that part of its environmental adaptation has to do with the the second chromosome," said John Mekalanos of Harvard Medical School. "It gives us very specific experiments that we can do to address the role of genes in the small chromosome."

Now that the genome has been sequenced, researchers say it will still be at least "two to three years" before more effective vaccines and better treatments for cholera become available.

Cholera is not the first bacteria to be sequenced. E-coli was sequenced in 1997.

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Centers for Disease Control and Prevention: Cholera Information
Cholera Information from the World Health Organization

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