The international team of investigators, who identified rare genetic variations among strains of the bacterium that causes leprosy, included Patrick J. Brennan, Ph.D., of Colorado State University in Fort Collins. Dr. Brennan is a grantee of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.
"Using modern genetic techniques, these researchers uncovered clues to the origin of a disease that, since ancient times, has been one of the most stigmatizing," notes NIAID Director Anthony S. Fauci, M.D. "Their findings may help public health officials better track and treat leprosy, which remains a significant problem in some parts of the world today."
The research team included scientists from institutions in the United States, France and seven other countries. Led by Stewart T. Cole, Ph.D., of the Institut Pasteur in Paris, the investigators scanned the genetic material of Mycobacterium leprae, the bacterium that causes leprosy, for tiny variations known as single nucleotide polymorphisms (SNPs). SNPs, pronounced "snips," are variations in a single "letter" of DNA's four-letter code. Scientists can use SNPs to trace the lineage of an organism, in this case M. leprae, and to develop a picture of how leprosy spread from its point of origin. The team looked for SNPs in 171 clinical specimens of M. leprae taken from people infected with the bacterium. The specimens came from 21 countries representing five continents.
Four types of SNP appeared in the samples, but their distribution was not random. Instead, the investigators