This paper was mentioned in this week’s ASM news digest, and it’s a really cool story of how Helicobacter pylori, the bacterium involved in stomach cancer, has co-evolved to exist along with humans. But, when a human population encounters a strain of Helicobacter from a different geographic location (an African strain being transmitted to people in South America), it seems to result in a higher incidence of cancer. The authors evaluated this by looking at populations from 2 towns in Columbia, one with a high rate of stomach cancer and one with a lower rate, though they’re geographically close to one another, then tracing back the ancestry of their colonizing Helicobacter strains. Really cool stuff!
Link to the original paper in PNAS: http://www.pnas.org/content/early/2014/01/08/1318093111
Link to the commentary in Nature: http://www.nature.com/news/human-microbe-mismatch-boosts-risk-of-stomach-cancer-1.14501