TB patient from Moncton school is doing well, poses low risk, says health officer

The person with tuberculosis at Bernice MacNaughton High School in Moncton is being treated and is "progressing very well," says the regional medical officer of health.

Dr. Yves Léger declined to say Thursday if it's a student, teacher or staff member who's infected with the serious respiratory disease, citing confidentiality.

"Of course, it is a situation that can be anxiety-provoking for parents and for students," he told reporters during a news conference. "We appreciate that."

"There are measures in place so that they're not posing a risk to the community until they've been deemed non-contagious."

Tuberculosis is caused by the bacteria mycobacterium tuberculosis and is spread from person to person through the air.

When someone with active TB coughs, sneezes, or sometimes even talks, tiny droplets containing TB germs are released into the air, where they can remain for hours.

But tuberculosis, or TB, isn't as contagious as some other diseases, such as measles, whooping cough or the flu, Léger stressed.

"Most people are, I would say, very low risk of being exposed. And for those that are exposed … nine out of 10 will never actually develop the disease." Those cases, referred to as latent, do not exhibit any symptoms and are not contagious.

Bernice MacNaughton High School has more than 800 students and about 65 teachers and other staff, according to its website.

The school sent a letter to students, parents and guardians on Wednesday, advising them of the confirmed case "in a member of the school community."

Public Health was informed "late last week," said Léger.

The person had symptoms, sought medical care and was tested, he said.

6th case in region this year

This is the sixth confirmed case of TB in the southeastern region so far this year, which is higher than usual.

Normally, the region sees between one and six cases a year, while the entire province usually sees between three and 12 cases, said Léger.

The provincial total to date was not immediately available on Thursday.

Last year, New Brunswick had six confirmed cases of active TB — three in the Saint John health region and three in the Fredericton health region, according to the Department of Health.

Public Health officials are investigating to determine who may have been exposed to the latest confirmed case, said Léger. Possible exposures could include households, schools or workplaces, through sports, hobbies or religious activities, and the community in general.

Officials can't start conducting diagnostic skin tests for at least eight weeks because that's how long it can take for the infection to be detected, he said.

"If you do it too early, you might get a negative result, but it could be what we call a false negative because your immune system hasn't had the time yet to build up to be able to respond to that skin test."

Léger said they will focus first on those considered at higher risk. Factors to be considered include the infectiousness of the case, the duration of exposure, whether the exposure occurred in close proximity, such as a classroom or a vehicle, or in a large setting, such as an auditorium, and the health condition of the individuals.

He expects it will be late January before he's able to determine whether the investigation can be wrapped up or needs to be expanded to include other people who were possibly exposed.

Noel Ward, who has two children who attend the school, told CBC News he's not overly concerned about the case of TB, especially compared with the outbreak of legionnaires' disease earlier this fall in Moncton.

"My main concern was that, you know, being in this area, where there was an outbreak of legionnaires', they were a lot more secretive, and I think it's very ironic that they're telling us so much about TB, which seems to be a low, low risk," he said.

"They didn't say anything about [the legionnaires'] outbreak, which is a much higher risk."

Legionnaires' is a severe form of pneumonia. Anyone who inhales mist or steam containing the bacteria can develop the disease, also known as legionellosis.

The outbreak, which was announced Aug. 1 and declared over Sept. 10, saw 16 people become ill and 15 be hospitalized.

The province has not disclosed the source of the legionnaires' outbreak. Léger previously told reporters that cooling towers in western Moncton were tested for legionella bacteria and confirmed to be the source.

Four new cases of legionnaires reported in the Moncton region since the outbreak ended do not appear to be related, he has said.

Bacteria can lay dormant for decades

With TB, when a person first becomes infected, the bacteria settle deep in their lungs, but then their immune system kicks in and traps the bacteria, preventing it from making the person sick, said Léger.

In nine out of 10 individuals, the bacteria will remain dormant, or latent, and not make the person sick, he said.

One out of 10 people who have latent TB will eventually develop active TB.

"The bacteria starts to overpower that person's immune system and starts to multiply and spread," causing the disease and symptoms.

In some cases, that happens soon after infection, said Léger.

"But for most it happens many decades later in life, when your immune system is weakened, either by disease, medication or age."

For the TB skin test, a small amount of non-infectious tuberculosis protein is injected under the skin of a person's arm. It can take two to three days for the skin to react to the injection for a positive result, according to the Public Health Agency of Canada.

Those who test positive require more tests to determine if they have the active form of tuberculosis.

Antibiotics can treat and prevent

Anyone identified as having latent TB will be offered antibiotics, which will "greatly reduce their risk of developing [active] TB down the road," said Léger.

Symptoms of active TB can include a bad cough, chest pain, weakness or fatigue, loss of appetite, weight loss, chills, fever or night sweats.

It can be treated by taking several antibiotics for between six months and a year, but if left untreated, it can be fatal.

Léger said he plans to meet with school staff this week and will hold an information session for parents at the school auditorium on Monday at 6:30 p.m. to provide them with more information and to answer any questions.

In 2017, there were eight confirmed cases across the province, down from 12 in 2016, the 2017 New Brunswick Communicable Disease Annual Surveillance Report shows.

The province's average case count of the previous five years was six. That's an average incidence rate of 0.8 per 100,000 population.

New Brunswick's annual average is "consistently lower" than the national rates, which have hovered at just under five per 100,000 in recent years, according to the report.