Although I'm not a doctor (disclaimer!), I can give some general advice based on research. Of course, you should definitely talk to your doctor directly or see a travel vaccination specialist, as a number of factors apply.
Claire Wong, from Worldwise Travellers Health Centre, said it was difficult to make specific vaccinations recommendations as every traveller and every trip was different.
"Travel medicine is a distinct speciality and involves much more than vaccines, and we feel it's important for travellers to discuss their trip with a travel health specialist," she said.
"The specialist will then make individualised recommendations on vaccinations, but also malaria prevention, food and water precautions, personal safety and security to name a few."
As a traveller, it's always a good idea to keep up with routine vaccinations, such as polio, diphtheria, and tetanus. I've looked at advice from the Centre for Disease Control (CDC), which says most travellers to Cambodia should get vaccinated against Hepatitis A and typhoid - particularly if you're visiting smaller cities or rural areas.
Both are spread through contaminated food and water.
Other viruses and diseases to be aware of are hepatitis B (spread through blood and sexual contact), japanese encephalitis (if staying longer than a month) and rabies (especially if you'll be far from medical care).
Similar advice applies to Burma, but the CDC also advises getting a polio vaccine - if you were vaccinated as a child, you should still get a booster shot.
Many people choose to take anti-malaria medication before travelling to Southeast Asia - however, appropriate medication depends on where you're going.
You'll need to start taking it before you leave as well. The risk depends on which areas you're visiting - less so in cities, more so in forested areas.
When I went to Vietnam, about half the people in my group chose to take anti-malarial medicine. I didn't, but I did get some pretty nasty looking bug bites, which made me a bit paranoid at times. So I'd recommend dousing yourself in bug spray - malaria or not, bites are itchy and annoying.