Perhaps Simon is mistaken about chloroquine (brand name Aralen). It has been used for a very long time and vivid dreams are not a reported side effect. Side effects are rare; occasionally itching, nausea, dizziness, headaches and blurred vision are reported.
I believe Simon may have confused chloroquine with mefloquine (brand name Larium) which does have the side effect of vivid dreams in some people. However, Larium is rarely prescribed for visitors to Belize, since chloroquine-resistent strains aren't a real factor Belize.
I personally take a heavy dose of an antimalarial closely related to chlorquine (hydroxychloroquine sulfate/ brand name Plaquenil) daily -- for another health problem unrelated to malaria -- and I have never had vivid dreams. (I do however turn green and sprout broccoli from my ears from time to time.)
Overall, in my opinion one's chances of getting malaria in San Pedro or on any of the Belize cayes are about the same as getting malaria in Miami.
There is malaria in Belize, but the incidence has dropped dramatically in recent years, since the peak in the early and mid-1990s. At one time Belize had a very high incidence of malaria based on the small population of the country, but happily things have improved. I think the latest numbers are a few hundred cases a year, mostly in remote areas among Guatemalan immigrants to Belize.
On the other hand, it does come down to a personal decision -- talk to a tropical medicine specialist or go to the CDC site for a conservative perspective. And if you are spending time in remote bush areas malaria prophylaxsis could be good insurance.
On dengue, certainly it is present in Belize especially in the late summer and fall after the rainy season, although Belize has escaped the near-epidemics that have swept Costa Rica, Honduras, El Salvador and other countries in the region. But I have not heard of any deaths in Belize from dengue -- the dangerous hemmoraghic variety is rare in Belize. I've had dengue -- it's sorta like the flu. And there is no preventative for it except avoiding the mozzies that carry it.
Typhoid in Belize? Sure, it occasionally does happen ... at about the same incidence as typhoid in Louisiana. And even the conservative CDC doesn't recommend typhoid sticks for Belize.
--Lan Sluder
www.belizefirst.com