Travellers should take medical advice at least three weeks before travelling to Thailand. Malaria is a risk outside Bangkok and the major tourist resorts and most physicians will advise immunisation against hepatitis A and typhoid fever. Yellow fever vaccination certificates are required from those travelling from infected areas. Since January 2005 there has been an increase in reported cases of dengue fever in the south, particularly the area near the border with Malaysia. There have been recent outbreaks of Avian Influenza among poultry, and although the risk of contracting the disease is slight, travellers should avoid contact with live birds. HIV is rife in the major cities and resorts and food and water-borne diseases are common; drinking bottled or sterilised water is strongly advised. Medical facilities are good in major cities, but good medical insurance is vital: without insurance, or cash/credit card, travellers will not be treated.