When Marina Ulanova began looking at the prevalence of a severe bacterial infection in the rural communities of northwestern Ontario, what she found surprised her. A worldwide vaccination push in the early 1990s had effectively wiped out the most virulent strain of the Haemophilus influenzae pathogen, which can cause meningitis, pneumonia and bacteremia, among other illnesses. Yet Ulanova’s team at the Northern Ontario School of Medicine in Thunder Bay stumbled upon a different strain of H. influenzae that was wreaking havoc on the First Nations groups of the region.

Further laboratory analyses indicated a striking degree of uniformity in the genetic and phenotypic characteristics of the pathogenic bacterium. “It was amazing,” says Ulanova. “They all looked like they belonged to the same clone.” Yet the cases had clearly originated independently; many of the infected individuals lived in communities so remote that they didn’t have road access.

[Read more at Nature Medicine (paywall) or download PDF // April 5, 2012]