Vibrio cholerae

Although they don't generally make headlines, Vibrio cholerae infections wreak havoc in areas of the world with poor sanitation, causing millions of cases of cholera and over 100,000 deaths each year.

Haiti did not have a single case of cholera until October 2010 -- 10 months after a devastating earthquake leveled the country on Jan. 12 of the same year, killing up to an estimated 300,000 people.