A bird flu pandemic is going to be a great disruption and test of humanity, but even more so to people who are mentally challenged, whether mentally retarded (MR) or who have psychiatric mental/emotional disorders.
Of course, all the physical ways of protecting ourselves from bird flu by remaining as isolated as possible, not physically touching people unless necessary, wearing Nanomasks and so on, apply to the mentally challenged as well as to everybody else.
Their extra risk comes from the impaired ability to adjust to a world where the bird flu virus is killing millions around the world, and the many consequences of that.
They may not understand that they should not go out, should not visit with friends, should not attend any adult day care, cannot go to work at their sheltered workshop and so on. Or that food can no longer be cooked but must come out of a can. Or that the lights may not work again for months. Or that the grocery store where they work is closed or that their job coach died from the flu. Or that batteries should be saved to operate the portable radio rather than a video game.
They may require patience and retraining in learning how to use a manual can opener, wash their bodies from a bucket or to keep a Nanomask snugly on their face at all time when out in public.
Schizoprenics may easily over-react to a bird flu pandemic. Imagine it's the end of the world, incorporate it into their own mental fantasies etc.
Paranoids may make the best adjustment to the realities of a bird flu pandemic. Although the bird flu virus is not out to get them personally, it is out to get all of us. During a bird flu pandemic, avoidance techniques are practical.
Depressed people will require close observation, since a bird flu pandemic will only encourage this emotion. Many people around the world will be feeling event-linked depression over the state of the world and grief for deceased friends and family.
Everybody will be feeling stressed out, so people who're already having problems coping emotionally will be all the more likely to look for a way out through suicide. Those who make the threat or attempt in an effort to get further help may not fully understand that a fully equiped ambulance and trained Emergency Medical Technicians are not a quick phone call to 911 away.
In their emotional state they may not understand that the local hospital and medical personnel are already too overloaded with bird flu patients. The extra help they need and want may simply not be there.
That leaves you to give them the emotional attention the need.
One major challenge during a serious and protracted pandemic will be obtaining prescription drugs. Check with their doctor about stockpiling an extra month or two of their medicine, in the event of a pandemic or other emergency.
You should also check with their doctor about care through the pandemic. Do they plan to stay available? They're first trained as regular physicians, so it is possible they would be pressed into service at a local hospital tending flu patients? Do they have any back up?
Check with their medical provider, but I suggest giving them some useful task that is not critical but which is important enough for them to understand they are contributing to the household during a situation that is difficult for everybody. Make it their job to put the tubs outside at night to catch any rainfall, or to help with the cooking, or to keep the dog chained in the backyard.
As much as possible, keep their minds on accomplishing the small but useful day to day tasks that survival depends on.