Where is Malaria present?
If you are backpacking the chances are you will pass through a malarial zone.
The main areas include South and Central America, Africa and most areas in Asia off the main tourist trail. There is generally not a risk in the majorly populated areas or main tourist spots, but always be cautious.
Well before you start travelling should check with your GP, travel health clinic or other agencies to see if you are passing through one of these areas.
Useful contact regarding malaria:
Ensure you have adequate travel insurance before you travel.
Next: Malaria prevention