Europeans Brought New Strains of Ulcer-Causing Bacterium to Pre-Columbian Americas (image) PLOS Share Print E-Mail Caption Distinct new sub-populations of Helicobacter pylori have evolved in North, Central and South America. Credit Kaisa Thorell, Koji Yahara and colleagues Usage Restrictions All figures and photographic images will be published under a Creative Commons Attribution License (CCAL), which allows them to be freely used, distributed, and built upon as long as proper attribution is given. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.