The intestine of an American cholera victim from the mid-1800s has yielded new clues to the evolution of the deadly bacterium and may help prevent future outbreaks, researchers said Wednesday.
Using the sample of an intestine, preserved in a jar at a Philadelphia medical museum, scientists reconstructed for the first time the genome of classical cholera, the predecessor of the modern-day strain.
Results published in The New England Journal of Medicine suggest this strain, which is behind five of seven deadly outbreaks in the 1800s, may be more virulent than its contemporary counterpart.
Researchers said they hope their discovery could lead to a better understanding of today's strain of cholera, known as El Tor, which replaced the classical strain in the 1960s and is blamed for recent epidemics like the one in post-earthquake Haiti.
"Understanding the evolution of an infectious disease has tremendous potential for understanding its epidemiology, how it changes over time and what events play a role in its jump into humans," said evolutionary geneticist Hendrik Poinar, associate professor and director of the McMaster University Ancient DNA Centre.
The preserved organ was crucial to the effort, since DNA from cholera resides only in soft tissues and cannot be detected in bone.
The type of cholera behind most of the 1800s outbreaks is believed to have originated in the Bay of Bengal off India.
