Doesn't it take just one tourist with malaria to bring it back?
replies(5):
> Certification is granted when a country proves that the transmission chain is interrupted for at least the previous three consecutive years.
And
> To get the WHO certification, a country must demonstrate the capacity to prevent the re-establishment of transmission.
If they've sufficiently damaged the vector one tourist alone cannot bring it back - the disease vector would also need to come back.
So even if you would somehow introduce a few busloads of Malaria-stricken people, that's not likely to re-introduce Malaria.