A 63-year-old Florida man hospitalized with pulmonary anthrax is an "isolated case" with no evidence of terrorism, Health and Human Services Secretary Tommy Thompson said.
"Officials are aggressively investigating the individual's schedule for the last few weeks and the source of the infection," Thompson said Thursday.
Anthrax has been discussed as a possible agent in a potential biological attack by terrorists, but it also is a naturally occurring bacterium that has caused past human infections.
The infections often are fatal. At least two other human cases have been identified since 1974, including one in Florida, officials said. Thompson said the most recent case was of a man in Texas earlier this year.
Officials: Isolated Case
Health officials said the British-born patient, identified as Bob Stevens, a Palm Beach newspaper photo editor who lives in Lantana, Fla., was admitted to an undisclosed hospital early Tuesday. They suspected he had meningitis until lab results indicated he had pulmonary anthrax.
"I want to make sure that everybody understands that anthrax is not contagious, and is not communicable, which means it is not spread from person to person," Thompson said. "If it is caught early enough, it can be prevented and treated with antibiotics."
"There's plenty of [antibiotic] supply available," Thompson added, saying there was enough to treat 2 million people for 60 days. "People should not go out of their way and do anything other than what they're doing."
Stevens reportedly is in grave condition. An infectious disease specialist at the hospital where Stevens is being treated said he is on a ventilator and is sedated.
Florida officials insisted residents should not be alarmed.
"There is no reason to think that this incident is anything other than what we have seen in the United States over recent years," Florida Lt. Gov. Frank Brogan said. "It is a rare illness but it has manifested itself in Florida many years ago, as well as other states in the country in more recent years. And there is no reason to believe at this juncture that this is anything other than the manifestation of a rare and obviously very serious illness that has found its way into the life of one individual."
Where Did He Catch It?
Stevens was described as an outdoorsman who reported flu-like symptoms after recently traveling to North Carolina. The Centers for Disease Control and the FBI are investigating and trying to retrace Stevens' steps in Florida and North Carolina.
Health experts are skeptical Stevens caught the disease in North Carolina based on the incubation period for anthrax of up to 60 days. An epidemiologist with the Florida Department of Health said he is certain the illness was contracted in Palm Beach County, where Stevens lived.
Anthrax infections are more commonly found in soil, sheep, cattle and horses, but can spread to humans who come into physical contact with infected animals or their products, or who breathe in anthrax spores. The current Florida case, the most serious type of anthrax, involves inhaling spores.
"It sounds as though this is someone who may have come in contact with some anthrax spores which can live, for instance, in dirt or soil for a long time," said Sue Bailey, former deputy assistant secretary of defense for health affairs.
North Carolina public health division spokeswoman Debbie Crane added there have been no reported cases of anthrax in the North Carolina areas the man visited.
"We know he visited Charlotte, Chimney Rock, and Duke University," she said. "We know that he began to feel badly last Sunday and left Duke University to drive back to south Florida."
Before the human case was announced, Martin Hugh-Jones, a professor at Louisiana State University's College of Veterinary Medicine, said the summer has been a relatively quiet one for anthrax cases in animals, though there were outbreaks.
"This year we're at the end of a very bad outbreak in northern Minnesota, a small outbreak in South Dakota and one outbreak in Alberta [Canada]," he said. "There were also a whole lot of dead deer with the disease found in west Texas."
"Last year was a bad year — about 250 animals died from it," he said. "But overall, it's not a major problem — especially compared to, say, parasites, pneumonia."
ABCNEWS' Michael S. James and Amanda Onion in New York, and Peter D'Oench in Miami, contributed to this report.