Search and Rescue personnel are particularly susceptible to this due to the very nature of their job.
Stress does have a cumulative effect on the body.
Someone who has been involved in numerous incidents without any lasting complications may suddenly develop the signs and symptoms of a stress reaction. Another example of the cumulative effect of stress is an individual who is experiencing other stressors such as marital problems, problems with children, or a recent death of a friend or relative, and who then is called out for a SAR incident. He may develop the signs and symptoms of a stress reaction in what may seem a particularly uneventful incident. People who are unprepared for the physical and mental strain of a SAR incident are particularly susceptible. In an incident where a particularly stressful situation develops, SAR people are at risk.