The truth about TB

Will my kid get it too? Why wasn't the school closed to prevent its spread?

These were some questions raised by parents when tuberculosis (TB) hit several preschools here.

In March, a staff member at a PAP Community Foundation Sparkletots preschool in Clementi was diagnosed with the disease. The other two cases, which occurred in August last year, affected teachers.

Such incidents are worrying, especially for parents. Misconceptions about the infectious disease, such as how it is spread, may further fuel fear and anxiety.

Just last week, a staff member at the Health Sciences Authority (HSA) blood bank was diagnosed with active TB. However, we should not be overly stressed by TB.

We get the experts to lift the fog.

A COLD OR FLU IS 
MORE CONTAGIOUS

TB is an airborne infection caused by the bacterium called mycobacterium tuberculosis, which means that it can be spread through the air.

But it is "much less contagious" than a viral infection such as the flu or a cold, said Dr Cynthia Chee, senior consultant at the Tuberculosis Control Unit at Tan Tock Seng Hospital, which sees about three quarters of all TB cases in Singapore.

"Only people with active TB, who are coughing germs into the air, are infectious to others," she added.

She explained that TB is typically spread when the bacteria is breathed in by people who are in close and prolonged contact with the infectious person - we are talking about days to weeks, rather than minutes to hours of exposure.

"It is not spread by contact with items or surfaces that the person has touched, sharing of toys, books, utensils or using the same washroom. And not everyone who is exposed will be infected. The body's immune system in most cases is able to defend itself against the germ," said Dr Chee.

IT IS NOT AS COMMON 
AS YOU THINK IT IS IN KIDS

Only a small proportion of TB cases occur in children, said Dr Chee.

Last year, children and teens under the age of 15 made up 1 per cent of TB cases among Singapore residents, according to figures from the TB Control Unit.

"There has not been an increase in the number of cases at preschools or schools in the last 10 years. Given that TB is fairly common in Singapore, it is likely that occasional cases will occur in various settings," said Dr Chee.

Children are at the highest risk of getting TB when someone in their household has active TB, said Associate Professor Thoon Koh Cheng, head and senior consultant at Infectious Disease Service, Department of Paediatrics at KKH Women's and Children's Hospital (KKH).

Other children at risk are those who have had an organ transplant or are on medication that suppress their immune system.

MOST VICTIMS 
ARE NOT INFECTIOUS

Nine in 10 people who are infected and have a healthy immune system will remain well throughout their lifetime, said Dr Chee.

This is known as a latent TB infection, whereby the body's immune system is able to hold the bacteria in a state of containment - the person does not have symptoms and will not spread TB to others, she explained.

Of this latent TB group, one in 10 will develop active TB later in life. This is when they may experience symptoms such as prolonged cough, fever, weight loss and fatigue, Dr Chee said.

KKH's Prof Thoon said certain health conditions like HIV infection, kidney failure that requires dialysis, and diabetes may cause the dormant TB germs to "awaken".

Infected kids under five are at a greater risk than adults of progressing to active TB and getting more severe forms.

For kids who did not undergo the Bacillus Calmette-Guerin (BCG) vaccination, this risk may be as high as 30 per cent, said Dr Chee.

IT DOESN'T ONLY 
AFFECT THE LUNGS

The most common organ affected by TB are the lungs, but the disease can also affect other parts of the body, including the brain, spine and eyes.

For example, if TB affects the brain, the child may get seizures and/or weakness or paralysis of the limbs.

If it affects the bones, the child may experience pain, swelling in the affected area and may develop a limp, said Prof Thoon.

BCG JAB HELPS AGAINST VERY SEVERE CASES, BUT DOES NOT PROVIDE COMPLETE IMMUNITY

Remember that BCG jab your baby received?

The vaccination is meant to protect babies and young children against very serious forms of the disease, such as TB meningitis (TB of the brain lining).

But your kid can still get other forms of TB after his jab.

While the BCG vaccination provides some protection against lung TB, the protection is "incomplete" and lung TB can still occur, said Dr Chee.

The World Health Organisation also does not recommend a booster BCG shot because studies have failed to show benefits, she added.

YOU ARE NOT INFECTIOUS AFTER TWO WEEKS OF TREATMENT

A common misconception is that an infected person can easily spread the disease while being treated.

Patients are considered not infectious after two weeks of treatment, said Dr Chee. There is no need to close places where an active TB case has been found.

Unlike other infectious diseases like hand, foot and mouth disease, TB germs cannot be passed via objects or surfaces.

Early detection and treatment through screening of the patient's close contacts can help prevent its spread.

"As patients would be on medical leave and started on treatment, there would be no risk of further exposure to workplace contacts once the diagnosis is made. Workplace or classmate contacts found to have latent TB infection are also not infectious," said Dr Chee.

It is important to detect and treat the condition early. Current treatment is effective in curing TB as long as your child takes the entire course of medication.

Treatment for TB usually lasts at least six months, with some cases stretching to nine months, she said.

In Singapore, patients with active TB undergo directly observed therapy under the National TB Programme - it is a procedure where medication is given under supervision at your home's nearest polyclinic.

There is also medication available for latent TB infection to prevent the person from getting the active form.

Children who require more specialised care may be referred to KKH for follow-up TB treatment, Prof Thoon said.

This story was first published in Young Parents magazine.