FDA issues rules for bird flu test on humans

WASHINGTON -- Federal guidelines rushed out yesterday should help companies develop tests capable of quickly singling out bird flu in infected humans, the Food and Drug Administration said.

The availability of rapid and accurate tests capable of pinpointing bird flu would be vital to checking any outbreak of the disease should it mutate to a form that can be passed from human to human.

Current rapid tests that use specimens collected from humans weren't designed or intended to detect the H5N1 strain responsible for bird flu, the FDA said. Nor can they distinguish among the various influenza A subtypes, some of which are rarely lethal.

The FDA hurriedly released the guidelines ''because prior public participation is not feasible given the national and global public health threat of pandemic influenza," the agency said.

The guidelines go into effect immediately, but are still subject to public comment. They spell out the steps companies have to follow to ensure the safe and effective use of in vitro diagnostic tests capable of detecting bird flu.

The H5N1 subtype responsible for bird flu is primarily a bird disease, although at least 108 people worldwide have died since 2003 after becoming infected.

For the past two decades, two other influenza A subtypes have been the primary causes of seasonal flu in humans. FDA officials expressed concern that existing tests for those seasonal strains might not be able to pick up newer subtypes, like H5N1, in samples from patients.

For that reason, they also recommend that manufacturers add warning labels to older tests, including an advisory that the results may need to be confirmed.