NEJM Interview: Edward Ryan on factors driving continued disease and death from cholera and opportunities for progress.

There are millions of cases of cholera and tens of thousands of related deaths worldwide each year, and the magnitude of outbreaks continues to increase. I'm Stephen Morrissey, Managing Editor of the New England Journal of Medicine, and I'm talking with Edward Ryan, Director of Global Infectious Diseases at Massachusetts General Hospital. Dr. Ryan has co-authored a perspective article about the continued challenges facing global cholera control. Dr. Ryan, what areas of the world and what populations tend to be most affected by cholera?

So most cases are currently reported from Africa, specifically sub-Saharan Africa, as well as Asia, especially South Asia. But large swaths, there's over fifty countries currently globally that are considered endemic for cholera. With regard to the type of individuals who are most at risk, they tend to be the most impoverished or disenfranchised individuals on the planet, and that largely relates to the fact that cholera is transmitted by unsafe water. And so since that's one of the fundamental aspects of economic development, individuals who don't have access to safely managed water or sanitary conditions are most at risk of cholera.

You say in your article that after the two thousand and ten cholera outbreak in Haiti, public health officials recognized that deployment of an effective vaccine could contribute to cholera response and prevention. So what progress has been made in terms of vaccination since then?

A great deal of progress. So the first was the recognition that vaccines should be part of a holistic plan to address cholera control. And the good news in two thousand and ten to thirteen range was that there was already a cholera vaccine that had been developed, an oral cholera vaccine, that was comprised of killed organisms that people could ingest. And so that vaccine was effectively taken off the shelf and moved forward. So the first was moving it into larger scale production and increasing the quantity of the vaccine. In about two thousand and thirteen or so, approximately five million dosages of the vaccine were available or could be made on an annual basis. And a great deal of work has gone in to increase the manufacturing capability so that now we have about sixty-five million dosages of that vaccine or comparable vaccines made annually. The vaccine was not only scaled up with regard to production itself, but simpler versions of the vaccine were developed and tested and have been deployed. The original oral cholera vaccine had a number of strains and biotypes and serotypes, and it was thought that a simpler version could be made, which obviously decreases production costs and increases production capacity. So those vaccines also have been endorsed by the Global Task Force on Cholera Control, also known as the GTFCC. And in a partnership with over fifty organizations, including Gavi, the Vaccine Alliance, a program was put together to use OCVs, which is what we call oral cholera vaccines, as part of a holistic approach, including with early case detection, outbreak response, appropriate education, improvements in water and sanitary conditions, surveillance systems, response systems at the national