Trips to/from Mexico seem to be a no no for the time being. However, whilst the swine flu seems to have a relatively mild effect on the rest of the world so far I think aircrew need to be extra cautious.
In Mexico those that have died , as far as has been reported ,have not been killed by flu alone but by secondary respiratory infection. The number of deaths in Mexico alone would perhaps suggest that there are additional environmantal factors which make individuals more susceptible to flu related complications. If this were not the case then it may be reasonable to expect mortality rates in other affected populations would be similar - as yet they are not.
Give the elevation of Mexico City, where most of the deaths have occured and the relatively high levels of pollution it is perhaps not surprising that a higher percentage of the population may have respiratory conditions which may render them more prone to infection.
Aircrew are more likley to be repeatedly exposed to virus carrying passengers who may be at different stages of infection. High altitude, recirculated air and a confined environment may prove to be a ready means for the virus to be redistributed. Flightcrew might be regarded as a unique population travelling form continent to continent and being exposed to mutated versions of the same flu virus. Screening pax is un workable and unmanageable but Aircrew should be extra vigilant.
Hopefully, there will be no correlation between altitude and the ability of infected patients to recover. I suspect the Mexican problem is much more likley to be related to underlying health issues.