If you are going up to the boarders of Laos or Burma I would recomend seeing your nurse at your local travel clinic who will advise you of what you require. I have travelled up north and around the borders plus across to Burma and was advised Hepatitus A, yellow fever and Malaria.
Its better to be safe than sorry.
However if your going to the tourist areas around Bangkok, Pattaya, Phuket etc you dont need anything apart from rubbers,