WASHINGTON?Eight days after the last anthrax diagnosis, a top federal health official said Tuesday the worst may be over. “For this episode, we’re out of the woods,” said Dr. Anthony Fauci of the National Institutes of Health.

But another attack, perhaps by some means other than the mail, can’t be ruled out. And it’s possible, although unlikely, that next month when thousands of people end their preventive antibiotics, a case or two might still pop up.

Could lingering contamination from the anthrax-tainted letters mailed to New York, Florida and Washington cause more infections? Fauci told The Associated Press that’s unlikely.

“However, another letter could come in addressed to whomever, you or me, who knows?” he added, saying doctors’ vigilance cannot wane.

But the most troublesome anthrax case is Kathy Nguyen’s. No one yet knows how Nguyen could have been infected.