Cerebral malaria can kill you in days. Cerebral malaria is widespread in West Africa and has killed aircrew, it's very nasty.
Malarone and Doxycycline are 2 prophylactic anti malarials in common use for aircrew, along with covering yourself in DEET and nets etc etc to stop getting bitten in the first place(mossies also carry Dengue fever btw).
Both have side effects, usually tummy related, but I reckon the alternative is not acceptable. Check out health.iafrica.com and lookup malaria/malarone.
Incidentally, I know an opthalmic nurse who contracted Cerebral malaria whilst in Africa and was treated for it down there. She said that the treatment was excellent, but the disease left her confused and forgetful/ unable to complete complex tasks, for several months after being declared clear of the parasite.