Vehicular accidents cause the most danger to travelers. This is due to different driving styles, poor road infrastructure, and poor maintenance of vehicles. Most likely you will catch a cold, get a little bit of flu, or have some travelers diarrhea while you are abroad. The likelihood you should contract any more serious disease or illness in great part depends on where you go and your behavior. To stay healthy there will be precautions you need to take, depending on your study site.
Most disease is food born so take precautions to eat only thoroughly cooked food.
In rural locations water may need to be treated. Find out from your program's administration if there are any recommendations regarding eating and drinking. Some sites may be experiencing a specific outbreak of disease. They can also provide information on recommended vaccinations. Travel to malaria risk zones poses a different difficulty.