Generally, travelers with stable, ongoing disabilities should prepare for an international trip in much the same way as any other traveler would. However, if you have a disability and are planning an international trip,

you should take three extra steps to ensure a safe and accessible trip.
1.    Consult with your travel agent or tour operator and make sure that resources are available to meet your needs.
2.    See a travel medicine doctor, or a doctor familiar with travel medicine, at least 4-6 weeks before you leave. He or she will tell you which vaccines or medicines you will need and give you additional recommendations that fit your needs.
3.    Research the resources available to people with disabilities in your destination.

Travelers with Weakened Immune Systems:
If your immune system is weakened from a disease such as HIV/AIDS or certain cancers, or from chemotherapy or medicines, talk to your doctor about the details of your travel plans. There may be added risks related to travel.
•    If your current medical status is unstable or puts your health at serious risk, it may be recommended that you not travel or postpone your trip until you can travel more safely.
•    Even if you can travel, you may or may not be able to have certain vaccines or take medications that are normally recommended for your destination or they may not be as effective.
•    If you do get sick while traveling, your illness may be more severe or you may have added complications to your existing condition.
Make sure that you fully understand all the risks involved with your travel plans and any ways to protect your health that your doctor recommends before you go.

From: CDC.gov