What pandemic has health officials worried about a future outbreak?
avian flu
bubonic plague
influenza
hiv/aids

The correct answer is: Avian Flu.

Influenza pandemics and epidemics have apparently occurred since at least the Middle Ages. When pandemics appear, 50% or more of an affected population can be infected in a single year, and the number of deaths caused by influenza can dramatically exceed what is normally expected. Since 1500, there appear to have been 13 or more influenza pandemics. In the past 120 years there were undoubted pandemics in 1889, 1918, 1957, 1968, and 1977. Although most experts believe we will face another influenza pandemic, it is impossible to predict when it will appear, where it will originate, or how severe it will be. The continuing spread of the highly pathogenic avian influenza viruses has heightened interest in pandemic prediction.

during the ming dynasty