The best remedy against malaria, like was said by Johe02:
"Don't get bitten."
Now, DEET and stuff like that will help, especially being in the open, I would say also as soon as it gets dark, when mosquitos are getting active, wear long sleeves and long trousers with socks, and avoid areas with lots of mosquitos.
Next to that I would never go anywhere without my mosquitonet for the night, small investment IMHO to prevent something that can still kill you, although in most cases it won't.
Make sure the mosquitonet is not too small and can be tugged in under the mattress, and still leaves room for you.
(otherwise mosquito's bite you THROUGH the net)
Hope this helps...
PS Will try out the Vegemite although I don't find it an attractive idea....
But maybe it explains that my daughter who really loves it never had malaria.....
Grtz, Herbie