Bird flu is continuing to spread across the United States, infecting wild birds and backyard poultry. It's causing egg prices to soar and availability to plummet.

Researchers have stressed that bird flu still poses a minimal risk to the general public, though that may change as the virus continues to circulate and potentially mutate. But the many empty shelves in stores and higher prices on the eggs that people can find have raised concerns among consumers about the safety of the egg supply.

The National Institutes of Health reports that avian influenza A virus, or bird flu, is now widespread in wild birds all over the world. The United States Department of Agriculture (USDA) also states that over 18 million birds have contracted the virus in this country.