Hello Andrew. I had been using Demal 200 in Nigeria for seven years and did not once contract malaria in all that time. I never knew whether it was because of the Demal 200 or sheer good luck. Last year a Nigerian colleague of mine, who used to suffer from malaria on a regular basis, asked me to get some for him. Since he started taking it his malaria has not recurred at all even though he admits to forgetting to take his daily dose more often than he should. He is utterly convinced that the Demal 200 is solely responsible for him being cured of malaria, and therefore so am I. Incidentally there are very few of my expat colleagues who have not suffered from malaria at one time or another and as far as I know none of them take Demal 200. I would not travel without it. Regards Rupert