According to the CDC, the travel vaccines you NEED to get for Southeast Asia are:
1. Updated routine vaccines - chickenpox, MMR, tetnus, polio, and yearly flu shot
2. Hepatitis A
The recommended vaccines are:
2. Japanese Encephalitis
4. Hepatitis B
6. Yellow Fever (required some places)
I decided to not get any of the recommended vaccines before moving to Southeast Asia and I haven't heard many stories about people getting mosquito infected diseases. As long as you apply mosquito repellent with DEET in rural areas you should be fine without them!
WHY VACCINES ARE IMPORTANT:
Although I assume most of you to be well-read and educated individuals, I thought I might add a quick section on why exactly it's important to get vaccines before you travel. Or just vaccines in general (as a biology major I consider myself quite psychotic about this topic...) When you get a disease, your body goes through a series of biological processes in order to make you better.
The process of getting sick starts with a certain "germ" multiplying at such a fast speed that the body can no longer effectively fight it off. When you're healthy, "germs" that start to multiply too fast are perceived as an attack against the body and the body's first line of defense cells are called in to keep those pesky germs under control. Most germs that are thought of as "bad," only cause disease because they grow to exponential numbers. Germs like "strep" and "staph" are actually necessary and regular parts to our healthy bodies. Like most things in life though, too much of something good can actually be bad.
So once your body's first line of defense is overpowered by a group of germs, the body calls in its second defense - antibodies! The body knows how to fight the disease in this step because a) antibodies were injected into the body through immunizations or b) the body has already fought this illness before and has created antibodies on its own. Either way, because the body has already built up immunity, in a very short amount of time, the multiplication of germs is halted as the body fights off your illness and you start to feel better in a short amount of time!!! YAYYYYY. This second step isn't that easy for everyone though. For the diseases people have not gotten vaccines for or have never built up immunity to, the body has to go through a series of intricate steps before it is able to effectively fight off a disease.
Think about it like this....Imagine you are doing a 1,000 piece puzzle. How many attempts does it take you to find the first two pieces that fit together? How long does it take you to do the whole thing? When your body is fighting off a disease, it is essentially doing a puzzle, except this puzzle has infinite amounts of pieces. Germs have distinct shapes on their ends that are kind of like these puzzle pieces. The body's job is to create a cell that fits into this end shape and then to mass produce cells in this exact shape to fight off the germs. It can be a long and painful process and the body does not always win... Soooo...the moral to this story is get your vaccines. Especially travel vaccines since the germs you are going to be around are completely foreign to your body. Getting a vaccine protects your body from these germs because they inject these puzzle pieces into your system (except they aren't the actual activated, harmful puzzle pieces your body would have to fight if it ACTUALLY got the disease. They are just like... knock-off puzzle pieces you found at goodwill that have the faded version picture on their front) so your body can start recognizing the shape and building antibodies that fit that shape before you ever even get the disease! It is brilliant!!! SCIENCE!!!!! SO GET VACCINES AND TELL PEOPLE TO GET THEM AS WELL, OK.