A new strain of the bird flu is killing residents of Shanghai. Should we be worried?

"It looks like it's not spread from person to person. Again, the concern is that the virus may change and it could be."

Dr. Catharine Troisi, associate professor at the University of Texas School of Public Health, says most Americans don't have the same close contact with birds as do the Chinese.

"The Asian community likes to have fresh poultry and so live birds are often sold in the markets."

The previous strain of bird flu didn't do much damage because it was only spread bird to human -- not person to person. Dr. Troisi says the previous strain was also easier to track -- because it killed birds.

"It does kill birds, so we know when something's happening. This we don't. So this may just be the tip of the ice berg or it may be the whole ice berg, we're just not sure."

The Chinese say the new strain is responsive to the drug Tamiflu and those who were diagnosed early could be cured.