In my training activities with new volunteers, I often use the analogy that their two years of overseas service is like a life stress test. I explain the use of stress testing for diagnosis of conditions such as coronary artery disease. I go on to say that if they have medical problems, these will probably get worse during the two years. However, if the volunteers learn to cope with these problems, they will be much stronger and able to adapt to future life stresses when they turn to whatever they do next. Most of the health problems we see in volunteers are relatively minor and predictable given the environment they live in.
Infectious diseases are by far the most common.
Even though we spend a lot of training time on water and food purification and preparation, diarrheal diseases are a common and almost expected part of Peace Corps life. The volunteers become quite adept at describing stool quality and frequency. The laboratory gets lots of business from us requesting tests for ova and parasites in stool specimens. While most diarrheal diseases are self-limited and presumed to be viral, we do see Giardia lamblia , Entamoeba histolytica , and a variety of bacterial stool infections. We do not vaccinate against cholera, as the efficacy of the vaccine is not very high.