Ottawa Public Health has advised some 400 federal government workers at an office building in the ByWard Market to get tested for tuberculosis after one of their colleagues contracted the infectious disease in August.

The public health agency notified the workers at 350 King Edward Ave., who include both federal public servants and contractors employed by outside companies, about the possible exposure earlier this month.

"As soon as we know somebody has tuberculosis we move into place to make sure that the exposure stops," said Dr. Robin Taylor, Ottawa's associate medical officer of health.

​She said public health professionals are working with the employers to ensure workers are given the appropriate information, skin testing for tuberculosis, and, if necessary, treatment for the disease. So far none of the other workers has tested positive for TB.

35th TB case this year

Dr. Robin Taylor of Ottawa Public Health says no other workers are known to have been infected. Taylor said the worker did not know they had the disease at the time of potential exposure. The disease was in the person's lungs, which is the most infectious form of tuberculosis.

Ottawa Public Health won't release any more information about the worker in order to protect their privacy.

"We want to make sure we followed up with anyone who might have been exposed, because tuberculosis is very treatable, and most people never end up being sick," Taylor said.

It's possible to be infected with tuberculosis bacteria but not develop the disease. In fact, some 90 per cent of people who become infected never develop the TB.

It's the 35th confirmed case of tuberculosis in Ottawa this year.

Taylor called the testing of other employees "precautionary."

Company sends HR reps

Nevertheless, one company with contract employees at the building has sent in its own human resources personel as "an opportunity to raise your concerns and questions," according to an email to affected workers.

Modis spokesperson Mary Beth Waddill told CBC: "In the event our employees could be exposed to a communicable disease, we work closely with Ottawa Public Health."

The skin test for tuberculosis is only effective if administered eight weeks after potential exposure to the disease. The skin test for tuberculosis is only reliable if it's administered eight weeks after potential exposure, meaning employees will have some time to wait before results are known.

Facts about TB