BRUNSWICK — Mid Coast Hospital placed a Brunswick man under quarantine Thursday when he visited the emergency room and claimed he was exposed to anthrax.

The threat was a false alarm, according to Brunswick police.

The man brought himself to the hospital at around 10:40 a.m., according to hospital spokeswoman Judy Kelsh. The hospital’s emergency department followed “biochemical exposure protocols” and immediately quarantined him in the hospital’s decontamination facilities, she said.

“We are not on lockdown, but we are taking precautions to avoid potential exposure to other patients and staff including isolation and rerouting as needed,” Kelsh said early Thursday afternoon. “We believe this is an isolated incident and no patients, visitors, or staff are in danger.”

A nurse who had initial contact with the man was quarantined as well, according to Kelsh. The nurse was released from isolation at 4:30 p.m.

Regular hospital operations were not affected.

Brunswick Police Cmdr. Mark Waltz said that, based on interviews with the 44-year-old man, police concluded there was no anthrax involved.

“This is not a legitimate threat,” Waltz said.  “It’s a product of his mental illness.” Waltz declined to comment on how the man claimed he was exposed to anthrax.

No criminal charges will be filed and the case is closed, he said.

Brunswick Deputy Fire Chief Don Koslosky said firefighters tested the man’s vehicle and a Brunswick home.

“Everything we’ve tested has come back negative,” he said.

The Maine National Guard’s Waterville-based Civil Support Team went to the hospital to do further testing, according to Koslosky. The Maine Center for Disease Control and Prevention was notified as well.

As of 4:30 p.m., “it was determined that there is no presence of anthrax spores in or around the patient and no risk of exposure to others,” Kelsh wrote in an email.

She declined to say if he’d been released from the hospital or if he would be transferred to different facility.

Anthrax is a serious bacterial infection that can be found in livestock. It’s uncommon for humans to be infected by anthrax in the U.S., according to the U.S. Centers for Disease Control. People get infected with anthrax when spores enter the body. When they become active, the bacteria can multiply, spread out in the body, produce toxins and cause severe illness. This can happen when people inhale or ingest spores, or an open wound such as a cut or scrape is exposed to spores.

All types of anthrax can be prevented and treated with antibiotics, according to the CDC. The agency adds that the bacteria that causes anthrax would be one of the biological agents most likely to be used in a bioterrorist attack.

There have been scares resulting from weaponized anthrax, including in 2001 when five people died after handling contaminated mail that had been sent to government offices and news agencies along the east coast. A total of 22 people were infected with anthrax that year.

Before this event, there had never been an intentional release of anthrax in the United States.

In April, federal prosecutors charged a Burlington woman with mailing a threatening letter containing a white powder to the Bangor home of Sen. Susan Collins last year. Inside the envelope was a flier claiming the powder was anthrax, the Portland Press Herald reported. The substance was actually a starch powder.

The last naturally occurring Anthrax case noted by the CDC occurred in 2011 when a man on a cross-country trip through Wyoming, Montana and the Dakotas arrived in Minnesota suffering from flu-like symptoms. He went to a hospital and was diagnosed with inhalation anthrax. He made a full recovery.

dmoore@timesrecord.com