Iceslider---While not the drug of choice, doxycycline is acceptable for malaria prophylaxis. Unless you are going for overnight stays on the mainland, I wouldn't worry about it. No malaria on the island. Hep shots are always good to have in a third world country. As far as the others, don't worry about it. While it may be possible (have been doing medical and dental work in Belize for 8 years), I have not seen any of those listed. My daughter did pick up a canine hookworm in her foot one year, but was easily treated once we got home and discovered what it was. Bottom line, wear your bug spray at sunrise and sunset and worry about more important things like what wonderful restaraunt you are going to eat at that night.
By the way, don't know who this "Dr. Glen" is thats giving these bad bits of medical advice on the board, but some of his suggestions are a little scary.