An emergency worker in a hazmat suit sprays another worker in a Pentagon parking lot after a woman who recently traveled to Africa vomited there on Friday. (Kevin Lamarque/Reuters)

A woman whose illness caused concern near the Pentagon and a four-hour quarantine for passengers on a bus in the District does not have Ebola, Arlington and Fairfax County officials confirmed Friday.

The woman vomited in a parking lot at the Pentagon about 9:15 a.m., and the county initially reported that she indicated she recently had been to western Africa. She was isolated at Inova Fairfax Hospital, and 22 people on a Pentagon shuttle bus, which she had briefly boarded, were kept quarantined for hours.

About 5 p.m., the two counties’ health departments said in a statement that she did not have the virus. The hospital said in a statement that she did not meet the criteria to be tested for Ebola.

The episode demonstrated the extraordinary precautions that authorities in the United States are taking to avoid transmission of the deadly virus, which has infected nearly 9,000 people in western Africa and three in America to date.

Two officials with knowledge of Friday’s incident said they do not believe the woman has recently traveled out of the United States. Mary Curtis, an Arlington County spokeswoman, said she does not know why county officials initially believed the patient had been in West Africa, but that the county’s health department no longer believes that to be the case.

The number of people being monitored for symptoms of Ebola in the U.S. is growing. Here's how the virus spreads and how contact tracing works to stop outbreaks. (Gillian Brockell/The Washington Post)

Steve Gordon, the woman’s boss at the public relations firm Total Spectrum, said the woman was suffering a severe illness and he does not think she has ever left the country.

Gordon said the ordeal left him concerned about his employee’s privacy. He said the Pentagon sent Marine officials to question him about the woman.

“I understand the mass hysteria out there,” Gordon said. “It’s the wildest thing I’ve ever seen. I’m trying to balance the requirements of following up on all this publicly with the overreach that is going on. I want to put this thing to bed.”

He said the woman transfers bus lines near the Pentagon on her daily commute to and from Fairfax County. He said he believes she became disoriented and mistakenly boarded the shuttle instead of a public bus.

The shuttle, carrying Marines and other Defense Department guests to a Marine Corps event, was parked in a commuter lot outside the Pentagon’s security perimeter.

Lt. Col. Eric Dent, public affairs officer for the Marine commandant, was on the bus. He said that it was bound for a change-of-command ceremony at the Marine Barracks in the District and was carrying several Marines, their spouses and invited civilian Defense Department workers.Dent said the woman walked to the back of the bus, used its bathroom, then left the bus without touching anyone on board. Afterward, he said, the driver told bus passengers that the woman had thrown up and collapsed outside. He saw emergency workers arrive.

The bus drove away, and when it was near the Marine Barracks at Eighth and I streets SE in Capitol Hill, the driver was summoned over the radio to stop. “We were told we weren’t allowed to get off the bus,” Dent said.

This is the largest outbreak of the Ebola virus in history.

D.C. police closed the 600 block of I Street SE, and the passengers were transferred to another bus to wait for health workers.

“The feeling on the bus was this is a little bit overdone,” Dent said. “Nobody had any physical contact with her. In hindsight, everyone is concerned about Ebola, and we have to err on the side of caution.”

Dr. Joxel Garcia, director of the District’s health department, said the city deployed an emergency response team that gathered contact information for the people on the bus. All were released and are under no further restrictions, Garcia said.

If the woman had been confirmed to have Ebola, the city would have monitored the passengers for illness “in a much more proactive way,” Garcia said. One of the passengers, he said, used a restroom on the bus after the sick woman.

The Pentagon Force Protection Agency first summoned Arlington County authorities to the Pentagon’s South Parking Lot after the woman’s illness was reported. Shortly before 10 a.m., she was taken to the Virginia Hospital Center, but she never got out of the ambulance. She was then taken to Fairfax Inova Hospital.

Tracy Connell, a spokeswoman for Inova, said the patient was immediately isolated. The Fairfax County Health Department interviewed her about her symptoms and her travel history and determined that she did not meet the criteria to be tested for Ebola, Connell said.

Before that, though, other health departments around the region mobilized in the afternoon to locate individuals who may have had contact with the patient, according to the Fairfax Health Department.

Connell said that the hospital’s staff members wore protective gear when treating the patient. “We’ve been preparing for this for a long time with all the proper personal protective equipment,” she said.

During the day, Gov. Terry McAuliffe (D) was briefed on the situation over the phone by Health Commissioner Marissa Levine, the governor’s spokesman, Brian Coy, said.

Meanwhile, an inmate in Loudoun County who was hospitalized Thursday out of concern that she might be infected with the Ebola virus was expected to be discharged from the hospital.

In a prepared statement, Loudoun officials said the inmate, who recorded a low-grade fever Thursday morning, was later determined to be of “no risk” to others.

The inmate, a middle-aged woman, had recently traveled from Ebola-affected areas of western Africa, according to authorities.

She was arrested on outstanding charges in Maryland, was kept in isolation and monitored at the Loudoun Adult Detention Center as a precautionary measure due to her travel history, officials said.

After experiencing a low-grade fever Thursday, the woman was transported to Inova Loudoun Hospital “out of an abundance of caution,” according to Loudoun Sheriff Mike Chapman.

Inova Loudoun Hospital spokesman Tony Raker said that medical officials had determined that the woman’s case did not merit Ebola testing.

Justin Jouvenal, Dana Hedgpeth, Jennifer Jenkins and Caitlin Gibson contributed to this report.