Moving to Mada and Malaria Medicine (Madagascar)

I am coming to Mada from Réunion in 11 days. As I am moving to Madagascar indefinitely and not just visiting for a short period of time, I don't know how to go about taking malaria medicine. Surely I won't be taking it my entire life, so how long do I take it? What are your thoughts? I would like to know how other expats handled the situation.

We will be starting off in Tana and also going to St Marie but eventually will be locating to the soth near Ft Dauphin.