For over a century the U.S. military has been sending troops to distant countries, and for all that time it has had to face a problem with of those personnel developing diarrhea (“the runs”) shortly after they arrive. The most common cause of this disease is entering an area where the local food and water will introduce a strange set of bacteria to your intestines (where food is digested). Until you acquire the local intestinal bacteria and it settles into your digestive system, you will have diarrhea. The process usually takes several weeks, although there are medications that can reduce the discomfort to a few days or less. But because there are thousands of different combinations of human intestinal bacterial on the planet, developing one medication that treats all occurrences of diarrhea has proved impossible so far. Moreover, some people adapt to new intestinal bacteria faster than others and spend less time dealing with diarrhea or don’t have it at all. In Iraq and Afghanistan it was found that, in any given month, about 30 percent of the troops would be dealing with diarrhea to some degree. This was bad for morale and reduced effectiveness.
Because of things like this diarrhea problem (which can sometimes be quite severe) in the last decade combat wounds and injuries have been very much a minority of casualties in the combat zone. For example, during the first year of fighting in Iraq (2003-4) 2,998 soldiers were killed or wounded in action, while 18,004 were evacuated from Iraq for other medical conditions (accidents and mostly disease, including severe diarrhea). The U.S. has known since World War II that areas like Iraq are full of strange (to Americans) and debilitating diseases. Efforts to find cures for a lot of these problems is hampered by the fact that few people (mostly foreigners) suffer from them and developing a cure is expensive and not justified by the small number (even including military victims) involved. Modern medicine can do wonderful things, as long as you have someone willing to put up the vast sums (often several billion dollars) to develop a safe and effective cure.