If there is an possibility of encountering mosquitoes, take the anti-malaria meds in all countries below Mexico. Even if they tell you that you do not need it you should consider it. I got malaria in Belize in 1987 and it was no fun. Got back to the states and nobody knew why I was getting 105 degree fevers every other day. My bed would be soaked with sweat so I had to sleep on towels every night. A friend called one afternoon and was so shocked at my incoherence she called my wife and told her to get me to emergency room. Docs had no idea what i had and tried to send me home. Wife refused to leave hospital with me (I do not remember any of this, I was out of it). Apparently an army doctor (this was in Huntsville Alabama) happened to walk by, saw my symptoms, he had been in Panama and declared "He has malaria". He told them to stain the blood to see the parasite.
During this two week period, I went from being already very thin to looking like death itself losing 20 lbs.
Once on the synthetic quinine, I recovered quickly but had two relapses.
Fortunately, the CA version is normally not the really bad strain and I am probably free of it. I get conflicting opinions on whether or not I can donate blood so I do not.
Take the meds.