You probably will not need shots for your cruise we have done those ports several times and never need them.
Take a good bug repellent with DEET.
Required & recommended are 2 different things but check with your doctor.
Devil's Island & Brazil do require proof of YF shots
Alexandr Pushkin, Carnival-Holiday, HAL-(old)Westerdam, Orient lines-Marco Polo, Royal Olympic-Olympic, NCL-Dream, Dawn-Princess, ACCL-Grande Caribe, Oceania-Insignia (3), Regatta(4) Marina (1) St Lawrence Cruise Lines-Canadian Empress
Scenic River cruise June 11,2012