Malaria is a risk throughout Madagascar. Speak to your doctor for advice about which antimalarial medication you should take.
The best way to reduce your risk of catching malaria is to avoid mosquito bites. Wear long, loose clothing that covers your arms and legs, apply a repellent with 50% DEET, and use a mosquito net if sleeping in an unscreened room. It’s best to take repellent with you in case there’s a local shortage.