New study finds that cholera vaccine helps protect community

By Kim Smiley

There are an estimated 3 to 5 million cases of cholera worldwide each year, believed to cause more than 100,000 deaths annually.  Cholera is rare in developed nations, but has been pandemic in Asia, Africa and Latin America for decades.  Researchers continue to search for an effective method to prevent cholera outbreaks.  A recent study found that a cheap oral vaccine is an effective tool to help prevent the spread of cholera.  The vaccine is not a perfect solution, but the study found that when two-thirds of the population was given the vaccine, cholera infections in an urban slum were reduced by nearly 40 percent.

The problem of cholera infections can be analyzed by building a Cause Map.  A Cause Map is a visual root cause analysis that intuitively lays out the cause-and-effect relationships of the multiple causes that contribute to an issue.  A Cause Map is built by asking “why” questions and documenting the answers in cause boxes.  To see how a Cause Map of this issue could be built, click on “Download PDF” above.

So why are so many people infected with cholera each year? Cholera is not generally passed from person to person and is predominantly spread through drinking water contaminated with cholera bacterium.  The feces of an infected individual carry cholera bacterium.  Cholera outbreaks occur in areas where there is a person infected with cholera in a location with poor sanitation infrastructure and inadequate water treatment.

Many efforts to reduce the number of cholera cases have focused on providing clean drinking water and providing sanitization equipment.  A recent study looked at three populations in Bangladesh: one was only given the vaccine, the second was given the vaccine, a hand-washing station and taught how to sterilize drinking water, and no intervention was done on the third population. The results showed that the vaccine alone was nearly as effective at preventing cholera as providing the vaccine along with a hand-washing station and instructions on sterilizing drinking water.  In the study, people were given two doses of the vaccine which costs about $3.70.

In an ideal world everyone would have access to clean, safe drinking water, but the resources required to build the needed infrastructure are not likely to be available any time in the near future.  Having a relatively cheap vaccine that is proven to slow the spread of cholera during an outbreak should prove to be a powerful tool in situations where access to clean water is limited.