There are a number of specific differentials, one of which is vestibular disorder and central vestibular disorder. The others are the particularly vivid dreaming states and the decline observed in patients suffering from after-exposure to mefloquine.
The other key diagnostic indicator is whether or not a person had a reaction at the time to taking the drug. In other words, they had a different health status prior to and immediately prior to taking mefloquine and their health status changed at the point at which they took the drug. That's a key critical indicator to identify those who had been directly affected.
I think Professor Sellers will probably have something to add to that as well.