Health issues and the quality of medical facilities vary enormously depending on where and how you travel in Vietnam. Many of the major cities are now very well developed, although travel to rural areas can expose you to a variety of health risks and inadequate medical care. Travellers tend to worry about contracting infectious diseases when in the tropics, but infections are a rare cause of serious illness or death in travellers. Pre-existing medical conditions such as heart disease, and accidental injury (especially traffic accidents), account for most life-threatening problems. Becoming ill in some way, however,is a relatively common thing. Fortunately most common illnesses can either be prevented with some common-sense behaviour or be treated easily with a well-stocked traveller's medical kit. The following advice is a general guide only and does not replace the advice of a doctor trained in tropical medicine.