Until the early 20th century, armies lost more troops to disease than combat when they marched out on campaign. This was taken for granted. But modern medical practices and drugs have steadily lowered these non-combat losses. But the non-combat illnesses are still there, and in a typically 21st century approach to the problem the Netherlands has declared that combat zones are a hazardous workplace and are paying disability to troops who return from peacekeeping missions with a variety of physical and psychological injuries. The basic problem to day is that soldiers from well scrubbed industrialized societies are venturing into disease ridden parts of the world. It's long been taken for granted that tourists to these areas had to be careful, and could expect to pick up some exotic diseases if they weren't careful, or even if they were. But soldiers don't spend most of their time living in well kept tourist hotels. Wandering around in the bush and getting close to the locals, the troops are more likely to be hit by the native microbes and viruses. Often, there are local diseases that are endemic (everyone has it, but hardly anyone notices) that have not even been identified in the West. So when Johnny comes limping home with a fever and headache of undetermined origin, people tend to get agitated. Thus we have Gulf War Syndrome and similar panics. Those who forget history are likely to repeat it.