The seventh cholera pandemic's severe impact on Africa represents a paradox. Why should a disease that had become well understood scientifically, and for which an effective and inexpensive therapy had emerged, have become more widespread and lethal, not less? The answer lies in the increased severity of risk factors, a minority of which stemmed from natural phenomena, and a majority from the deteriorating social, political, and economic conditions most sub-Saharan Africans endured after the mid-1970s.

As indicated in the introduction to this book, the quality and provenance of epidemiological statistics for cholera are colored by political and other considerations. The traditional homeland of cholera, Bangladesh, has as of 2008 not reported annual cholera cases to the WHO. It is impossible to know how many people suffer and die from cholera, given its confusion with other forms of acute diarrhea. Some reporting might overestimate reported cholera by assuming, as is routinely done, that if a wide outbreak occurs, then cholera drives out other diarrheas. But in a diarrhea epidemic in Dhaka following severe floods in 2004, the rate of cholera infection was only 22 percent compared to other acute diarrheas. This would, of course, inflate cholera rates. Yet denial and fear lead to the more likely prospect that, in general, cholera cases are underreported everywhere. One study estimates the annual global burden of cholera runs in the millions rather than one or two hundred thousand.