Consider the fact that we usually tell travelers to drink only water or beverages that bottled or have been boiled. Similarly, we advise that they avoid salads and raw fruits and vegetables, sticking to foods that have been thoroughly cooked and served hot.
VFRs not only consider such advice unnecessary and foolish, they simply cannot follow such rules. They are not usually staying in hotels or locations where they have some control of what they eat or drink. Rather, they are staying with family or friends and are expected to eat what their host eats. After all, who is going to turn down a chance to sample the recipe that their auntie is most famous for?
People who have grown up in the culture that they are visiting often believe that, having lived there before, they are immune to the diseases that we warn other travelers about. Unfortunately, this simply is not the case. Immunity that may have been acquired in childhood to respiratory or gastro-intestinal diseases rapidly wanes once one stops being exposed to them. Thus, VFRs are more likely than other travelers to come down with traveler’s diarrhea, typhoid, tuberculosis and other infectious diseases. Hepatitis A, B, C and E are other examples. This is due to the deadly combination of more prolonged and intense exposure plus a lack of preventive measures.