Tourists and Travellers who come to Southeast Asia are usually very concerned about safety and health. It's generally more safe here than in most other parts of the world and generally easy to remain healthy; the dangers are mostly overestimated or self-caused.
Sketch of an Anopheles Mosquito.
Nevertheless I want to point out one potential threat here.
More dangerous than all the scary animals like tigers, cobras, king cobras, crocodiles and so on are the mosquitoes (Spanish / Portuguese for 'little fly'), or at least a few certain kinds of mosquitoes who transfer dangerous diseases. The verymost kinds of mosquitoes do not transfer diseases, although, in more seldom cases, they can cause various other infections when transmitting bacterias, viruses or other parasites into the human body.
Various kinds of mosquito - transmitted tropical diseases are malaria, dengue fever, chikungunya fever, yellow fever, West-Nile fever, Rift-Valley fever, encephalitis and more. Some mosquitoes transfer parasitarian worms who can live in the human vascular system. Even HIV/AIDS can still not be completely excluded from the list of diseases transmitted by the nasty insects, but it's at least considered highly unprobable.
Apart from these health threats mosquitoes are simply annoying and can spoil enjoying time or cause sleepless nights.