Let their be no secret about it ,I am not a fan of the CDC.
but you should look at what they say here.
A Special Note about Antimalarial Drugs
You should purchase your antimalarial drugs before travel. Drugs purchased overseas may not be manufactured according to United States standards and may not be effective. They also may be dangerous, contain counterfeit medications or contaminants, or be combinations of drugs that are not safe to use.
Halofantrine (marketed as Halfan) is widely used overseas to treat malaria. CDC recommends that you do NOT use halofantrine because of serious heart-related side effects, including deaths. You should avoid using antimalarial drugs that are not recommended unless you have been diagnosed with life-threatening malaria and no other options are immediately available.
For detailed information about these antimalarial drugs, see Information for the Public: Prescription Drugs for Malaria.
The CDC is the source of information that Malaria is in Belize.
check other sources and you hear a very different story.
It would be my advice to also note ;
Side effects from chloroquine phosphate
* loss of appetite
* upset stomach
* stomach pain
* skin rash or itching
* hair loss
* mood or mental changes
* seeing light flashes and streaks
* blurred vision
* reading or seeing difficulties (words disappear, seeing half an object, misty or foggy vision)
* difficulty hearing
* ringing in ears
* muscle weakness
* upset stomach
* irregular heartbeats
* difficulty breathing
Ask around a bit more