An isolated case of anthrax infection was confirmed last night in a man at a Florida hospital, but there was no evidence of a biological warfare assault, US officials said.
The 63-year-old man was described as being critically ill by the hospital near West Palm Beach where he was being treated.
Health and Human Services Secretary Mr Tommy Thompson told a White House news briefing the victim reported to a Florida hospital on Monday and was confirmed to have anthrax - apparently of the inhalation variety.
"Based on what we know at this point, it appears that it's an isolated case," Mr Thompson said.
He said the man was an outdoorsman who could have picked up the infection from spores on his clothes and was known to have drunk water from a creek recently.
Anthrax - a deadly bacterial disease spread by spores and generally confined to sheep, cattle, horses, goats and pigs - is seen as a likely agent in any biological warfare attack because it can be deployed relatively easily.
Inhalation anthrax, which infects the lungs, is usually fatal. Anthrax has been experimented with as a warfare agent but its use is banned by international treaty.
AP