Researchers develop method to track cholera changes

A new technique recently developed by researchers at the University of Florida is capable of tracking the molecular changes that occur in cholera strains during an epidemic.

The results of the UF study, which will hopefully lead to a means of halting the disease’s progression, have been published in the journal Emerging Infectious Diseases, according to

Judy Johnson, an author of the paper, is a UF College of Medicine professor and member of the Emerging Pathogens Institute.

“Cholera spreads quickly through contaminated food and water and can survive in the environment,” Johnson said, according to “Tracking the spread in real-time, at a community level, is essential in helping identify sources of contamination so that they can be eliminated, stopping the spread of disease before it gets worse.”

The paper is the result of research conducted in Haiti during the recent outbreak of cholera that killed approximately 4,500 people, according to the World Health Organization.  

The UF researchers collected stool samples from 19 patients suffering from severe diarrhea at St. Marc’s Hospital in the Léogâne region. The samples were examined at the Emerging Pathogens Institute at UF, where the scientists used molecular typing, or fingerprinting, to follow the rapidly changing areas of the cholera genome.

In 187 bacterial colony selections that were examined, the researchers found that, even in individual patients, the DNA sequences were beginning to diversify, reports. Although all of the isolates could be traced back to a singular cholera clone introduced into Haiti, the molecular signature changed as the epidemic wore on.

By following these unique signatures, scientists can see how the disease spreads, regardless of the means of contamination.

The molecular typing technique can also be useful in examining where strains persist in the environment. In countries like Bangladesh and India, where cholera is endemic, different strains of the disease can typically exist only miles apart, but have entirely different genetic profiles. Multiple strains can even infect the same individual.

“Although there are changes happening in the Haitian strains, we have also confirmed that there’s little diversity in them,” Afsar Ali, the lead author of the paper and a UF professor, said, according to “This is significant because it means there was a single introduction of a cholera strain into the country.”

The UF researchers have made no conclusions about how cholera was introduced into Haiti, though several media reports have suggested Nepalese peacekeepers stationed in the country may have contributed to the outbreak.

“It appears that the first several cases of cholera had resulted from people drinking contaminated river water, and water should be considered the major driver of the cholera epidemic in Haiti,” Ali said, reports. “However, it’s yet to be validated that the introduction of the cholera germ in the water happened via human fecal excretion.”