It's true that these observational cohort studies don't provide the same level of confidence. Nevertheless, we have this study, and it follows the same direction as a number of other studies—some in military groups, some in non-military groups, short-term travellers and long-term travellers. We have accumulating evidence that generally points in the same direction, which is that it's been very difficult to show that the long-term events after mefloquine happen at a rate any different from what you see with any other drug.
The evidence is that either it doesn't happen, or if it does happen, it has to be very rare. The accumulated evidence of this study, together with all the other ones, such as what is presented in the Cochrane review, is that it has to be very rare. Then there's the question of whether the rarity of adverse events negates their value, when the drug is used in certain ways. There are always ways, when there are adverse events, to switch to other drugs. What I would say, however, based on the evidence, is that either there are no long-term effects or those effects are very rare. It's very hard to tell the two apart.