Tangata, what the institute is saying makes sense for your situation but not necessarily for others. There are two antimalarials that are effective world-wide: doxycycline and malarone. Malarone is not available in Thailand, but it has the fewest side effects and you have to take it for only a week after returning. Doxy is just fine for long-term use, it is often used for years at a time for other conditions. It can have some side effects that are unpleasant, but not dangerous (unless you are allergic to it). The downside for most people is that they would have to take it for a month after returning from the risk area.

"Incubation" period . . . it's about 10 days to four weeks depending on which of the strains is the infective agent.

Tangata - With all due respect to Kathie, I am not sure what the institute says does make much sense. I contracted malaria in Vietnam and did not have any symptoms until I returned to the UK several weeks later. I was hospitalised and tested regualrly over a period of several days. The parasite did not show up for the first couple of tests so I am not sure that one test would prove with any certainty that the parasite was not present. having said this, this happened 15/16 years ago so maybe the tests have improved. In my case the treatment itself was not very pleasant as I had an allergic reaction to Quinine which was almost as bad as the malaria!

In response to the OP original question, I would not bother with prophylactics for BKK or indeed most of Thailand but anywhere else the first thing I would do is to consult a recognised travel doctor.

For the places you're going and the type of accommodation you'll be in, it's not necessary.