Spent many days in West Africa, lived in South Africa, travelled in South America. I took Mefloquin while on a trip to Kruger Park in sA with  bus full of Canadian geologists. At least three of us had horrifying nightmares of the deaths of close family members including children and stopped taking it. 

I now use liberal quantities of Deet laden repellants in these areas and leave it at that. I'm counting on anti-malarial drugs to save me in the event of infection. I had full blown malaria once after a trip in Sierra Leone and took the week long cure.

I will never again use Mefloquin, no matter what.  The anguish caused by the visions it created is still  vivid memory today, 23 years later.