Scientists have learned a bit more about the bacterium responsible for epidemic dysentery. They've conducted the largest genetic study to date to not only learn a bit more about its antibiotic resistance but also to trace the path of the bacterium worldwide.
The bacterium, in this case, is Shigella dysenteriae type 1. This bacterium can cause life-threatening bloody diarrhea and has been responsible for thousands of deaths. The last epidemic of dysentery occurred in Central Africa and killed as many as 20,000 people between 1969 and 1972.
In order to better understand the disease and the different strains of the bacterium, the researchers undertook a massive genomic study. In all, they analyzed more than 330 strains of S. dysenteriae type 1 that were isolated between 1915 and 2011.
So what did they find? The researchers discovered that the type 1 strain has existed since at least the 19th century. This strain has, since then, spread across the globe. Not only that, but the current pathogen that's endemic in Africa and Asia originally came from Europe.
"Analyzing the full genomes of all these Shigella dysenteriae strains collected over a huge timeframe and from such an array of different countries provided us with an unprecedented insight into the historical spread of this pathogen," said Nicholas Thomson, leader of the Bacterial Genomics and Evolution group at the Sanger Institute. "This was needed because there are still many unanswered questions relating this infamous and important bacterial pathogen. It was achieved by combining high resolution genomic research data with the detailed information recording the provenance of each sample from a large number of dedicated groups."
The researchers were also able to trace the path of the bacterium worldwide over time. This revealed that colonization by the Europeans and migrations were the major causes of spreading the pathogen.
"This bacterium is still in circulation, and could be responsible for future epidemics if conditions should prove favorable-such as a large gathering of people without access to drinking water or treatment of human waste," said Francois-Xavier Weill, one of the researchers. "This study highlights the need for an effective vaccine, which will be crucial for controlling this disease in the future in view of the reduced efficacy of antibiotics."
The findings are published in the March 2016 journal Nature Microbiology.
