Your primary goal should be to stay healthy while you're away, but it can sometimes be unavoidable even with vaccinations and special precautions. In case of emergency, you should know if your health insurance covers treatment while you're away. Medicare/Medicaid, for example, won't pay for medical services you receive abroad. Some insurance policies will cover only limited services when you are traveling outside of the United States. Even few companies will pay for your return trip if you become sick and need to return home immediately.
If your health coverage is limited or ineffective while traveling, you might want to consider supplementing your regular health insurance coverage with traveler's insurance. Traveler's insurance will cover preexisting conditions including HIV and will cover the cost of MedEvac if you are severely injured and need to be air lifted to a hospital. If you're traveling with a tour company, traveler's insurance may be included in your package. Check with your tour company before you purchase a supplemental plan.