The best way to prevent tropical diseases, is to protect yourself from insects that carry the parasite that cause them. Easier said than done however. But by wearing long sleeves, pants etc... and spraying yourself with a good quality insect repellent to keep mosquitos away is a good way also. As you may know insects are the biggest carrier of malaria in the tropics. Insects like these tend to bite at night. So if your outside during the evening, you also might want to consider some cheap bed netting, or a tent that keeps mosquitos and other bugs out. Children are particularly susceptible to the effects caused to them by tropical diseases. There are new vaccinations that are up and coming that will help with the future prevention of these terrible diseases carried by insects. Hope this helps somewhat.