What is it called when you want to work in poor countries for a living?

What is it called when you want to work in poor countries for a living?
What is the job called when you want to go to poor countries, live with poor people and help them. Also, to write reports or books on their way of living. I know this is related to Geography and some economics, but I want to know what that job is called. I’m not volunteering, I want to get actual pay for working there because I want to do it for a living.

Answer by Marc
There aren’t many organizations that pay you well to play “white man’s burden” in Africa. Consider some more stable, backup careers.

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