Hello, 13 months ago I worked in Nigeria, Africa for a period of 6 weeks. During which time I took Malarone tables daily. I think I was only bitten once or twice when there – but have never had Malaria. I currently carry a Malaria Risk Card in my wallet. At the time I was told I could potentially contract Malaria up to a period of 2 years after exposure – is this correct, or can I now remove the Risk Cards from my wallet?
If you never had malaria while you were in Nigeria, then you certainly would not still be at risk from it now. The only case in which you might still be at risk is if you had been diagnosed with either Plasmdodium ovale or P. vivax (two of the five forms of malaria that infect humans) – these can cause relapses months or even years after initial infection.
However, as I said above, since you did not have malaria at all, this does not apply to you. It is true that malaria has a latent phase, and so can sometimes only start to cause symptoms after someone returns home from a malarial area, but this period is usually one or two weeks, and certainly not months or years!