The tourism offices abroad have been instructed to meet with the airlines and tour operators and the press to provide updates on the situation. Personally, I would not take chloroquine but rather use a repellent if taking an excursion. I understand that taking this after is easier on the body than taking it as prophylaxis. To me it doesn't make sense because the chances of one getting malaria are very very minute. That is there is no alert out to Dominicans or foreign residents to take it as prophylaxis, regardless where they live, even on the border with Haiti.
Bottom line, if the mosquito doesn't bite you, it can't infect you. CDC says:
Protect yourself from mosquito bites:
Pay special attention to mosquito protection between dusk and dawn. This is when the type of mosquito whose bite transmits malaria is active.
Wear long-sleeved shirts, long pants, and hats.
Use insect repellents that contain DEET (diethylmethyltoluamide).
To understand malaria in perspective, see
http://www.dr1.com/news/2004/120304_malaria.shtml