I live on Ambergris Caye. Caye Caulker as anyone who knows me will attest to, is my get away. In fact I just "got away" there 2 weeks ago, and go over about twice a month. I travel alone and as such try to be reasonable and responsible. I always have a great time and have made some great friends. The last time I went over I stayed at Caye Reef and loved it. I felt safe, and had the best sleep I'd had in a long time.
I have also lived on the mainland in "mosquito land" and just like my native British Columbia where West Nile disease lurks, you try not to get all bitten up. Insect repellent and common sense will get you a long way.
By the way, someone mentioned Cuba less than favorably, and I would just like to put a good word in for Old Havana and Varadero, I have been 4 times,and can't wait to go back.
I have found with my overactive Capricorn mind, that at some point I have to stop researching every single aspect of my upcoming travel destination or eventually I find the dark underbelly. Keep up the positive thoughts, and have a great time!