A college student who died of tuberculosis Friday at Memorial Hospital could have had the contagious form of the disease for up to four months, but health authorities say the public health risk is low.

Kalpana Dangol, 19, arrived at the hospital about 12:30 a.m. Friday. She later died of complications related to tuberculosis.

Dangol took spring courses at Colorado State University at Pueblo but lived in Colorado Springs, health authorities said at a news conference Monday.

Deaths from TB in Colorado are rare, health officials said.

The El Paso County Coroner's Office identified Dangol on Monday afternoon, and listed her cause of death as sepsis, a poisoning from the spread of bacteria. TB invaded other parts of her body, including her colon, which became eroded and perforated.

The perforation of her colon caused bacteria to move into her bloodstream, Dr. Robert Bux said.

Health and CSU officials refused to identify the woman during the earlier news conference, citing state privacy law. Chief Medical Officer Ned Calonge, of the Colorado Department of Public Health and Environment, said he was confident health authorities could investigate who may have been exposed without notifying the general public.

He and other health officials did not know how many people might need tests.

Calonge said Dangol, of Nepal, likely contracted the disease from her native country, where TB is endemic, but did not travel during the time period where she could have been contagious.

He said she probably did not have the rare multidrug-resistant or extensively drug resistant strains of TB. Those forms of TB have a higher mortality rate, said Jim Hunger, assistant to the director for San Francisco Department of Health's TB Control Center.

TB, which is spread by air, is usually contracted through prolonged exposures and in poorly ventilated areas. Most people exposed to it do not become infected.

"It is not easy to catch tuberculosis," said Dr. Bernadette Albanese, medical director for the El Paso County Department of Health and Environment.

Memorial's CEO, Dick Eitel, told the City Council on Monday afternoon that a dozen hospital staff members were exposed before diagnosis. They will be monitored and tested for TB, but Eitel said he believed their chances of contracting the disease is "very, very low." He did not explain the basis for his belief.

The woman came to the hospital complaining of abdominal problems. Caregivers suspected a communicable disease and placed the woman in isolation in the emergency room.

He didn't say how long the woman remained in the emergency room and how long it took for a diagnosis to be determined.

"I think all our staff members were protected once the diagnosis was made," he said. He declined to tell reporters at the news conference whether the woman arrived by ambulance or was brought to the ER by family or friends.

The determination that Dangol did not have active TB before February was based on a "clinical" finding, although health officials declined to elaborate.

The investigation begins with people who had the closest and most frequent contact with Dangol, and authorities work out to a broader group of people in "circles." When there are no positive tests for latent TB, health officials know they've caught all possible exposures. The methods have been used since 1948.

Cases of TB are low in Colorado Springs compared with other areas. The state records about 120 cases of active TB a year.