bird flu

A flu strain deadly to chickens and turkeys is striking farms in the West and Midwest. This week, it hit an Iowa facility with millions of egg-laying hens. No one knows how it's entering houses.

The sloppy handling by federal scientists of the world's scariest germs must stop, says the dismayed head of the Centers for Disease Control and Prevention. Are his new rules enough?

Is the world on the verge of a pandemic? There are three reasons to think so. Two flu viruses are active, and a virus that bears a resemblance to SARS has cropped up in the Middle East. Each has devastating potential, but many early warnings of past pandemics have failed to materialize.

In early 2012, experiments that made H5N1 bird flu more contagious caused an uproar. People feared that mutant viruses could escape the lab and kill people. To prevent a repeat, the government has unveiled a policy describing how scientists should study dangerous pathogens and toxins.

After researchers created versions of the bird flu virus that could spread more easily, critics began to worry that the work could spawn a pandemic if a virus escaped from the lab. After halting their work for more than a year, scientists now say the benefits outweigh the risks, and they are set to restart their experiments.

When scientists figured out how to make the deadly H5N1 virus more contagious, a debate ignited about whether to publish the research and do more experiments. Over the past year, scientists published the contentious work, but they still can't agree on the field's future.