Tuberculosis (TB) is one of the world’s most deadliest infectious diseases, second only to COVID-191. If left untreated, it can be fatal. TB is endemic in Singapore, with approximately 30% of the elderly infected with latent TB2. It generally affects the lungs (pulmonary TB) but can affect other parts of the body (Extrapulmonary TB), such as the brain, kidneys, and spine.
There are two types of TB infections3:
Latent TB: also known as inactive TB, individuals with latent TB will not have any symptoms and they will not be contagious; this means they will not spread TB to others. Most people with latent TB can go their whole lives without showing any symptoms. However, if the immune system weakens, latent TB can develop to active TB.
Active TB: also known as TB disease, individuals with active TB have symptoms and are contagious; this means they can spread TB to others. They will remain contagious until approximately 2 weeks after treatment has started.
What causes Tuberculosis (TB)?
TB is caused by the bacteria, Mycobacterium tuberculosis. It can spread from individuals with an active TB infection via airborne water droplets released when he/she speaks, coughs, sneezes, laughs, or sings. Although TB is infectious, it does not spread easily, you will have to spend a substantial amount of time with an infected individual to catch it.
What are the symptoms of Tuberculosis (TB)?
Individuals with latent TB will not have any symptoms. However, individuals with active TB may show one more of the following symptoms:
Chronic cough (lasts longer than 2 weeks)
Pain in your chest
Unintentional weight loss
Fatigue or lethargy
Is Tuberculosis (TB) painful?
Some people with TB may experience chest pains.
Who is at risk of Tuberculosis (TB) in Singapore?
There are several factors that may increase your risk of developing active TB after infection, these are4:
Chronic medical conditions: individuals with diabetes, end-stage kidney disease, cancer
Malnutrition: not having adequate nutrients can affect the effectiveness of your immune system.
Long-term use of alcohol or smoking: these can weaken your immune system, making you more susceptible.
HIV positive: individuals infected with the human immunodeficiency virus (HIV) tend to have a compromised immune system, making them more susceptible to developing active TB.
Medication: some medications work by suppressing the immune system, thereby increasing the risk of active TB. These medications include those that are used to treat lupus, cancer, rheumatoid arthritis, psoriasis, Crohn’s disease, etc.
Geographic locations: living or travelling to areas (e.g., Singapore, Malaysia, India) where TB is endemic can increase your risk.
How is Tuberculosis (TB) diagnosed in Singapore?
If TB is suspected, whether latent or active, the following diagnostic tests may be conducted:
Skin test: also known as the Mantoux tuberculin skin test (TST), a purified protein derivative will be injected under the forearm skin. If there is a reaction of approximately 5mm or more after a few days, it is considered a positive skin test.
Blood test: also known as Interferon Gamma Release Assay (IGRA), measures the reactivity of your immune system to TB.
X-ray: an x-ray of your lungs will be taken to identify spots on your lungs which could be a sign of TB.
Sputum test: mucus from deep within your lungs will be tested for TB.
Computed tomography scans (CT-scan): like an x-ray but with clearer and more accurate visualisation of the lungs.
Bronchoscopy: a long, thin tube with a light and camera attached at one end will be inserted into your throat and gently guided down to your lungs.
Lung biopsy: samples of your lung will be taken and biopsied for signs of infection.
If any of the above tests come back as positive, which indicates an infection by the TB bacteria, treatment should be started as soon as possible, even if you are not showing any symptoms (latent TB).
What are the treatment options for Tuberculosis (TB) in Singapore?
Treatment options depend on whether the infection is latent or active.
Latent TB: two types of antibiotics, Rifampicin (RIF) and Isoniazid (INH) are used to prevent latent TB from progressing to active TB. They are prescribed for four (for RIF) or six (for INH) months and MUST be completed5.
Active TB: isoniazid, rifampicin, pyrazinamide, and ethambutol or streptomycin are administered to obliterate the TB bacteria. They are prescribed for six to nine months and MUST be completed6.
All prescribed antibiotic medication MUST be completed, even if there are no symptoms of TB. If antibiotics are not completed, the TB bacteria may become drug-resistant, making them difficult and almost impossible to kill.
Frequently asked questions
Is tuberculosis contagious?
Yes, tuberculosis is contagious.
Can tuberculosis be sexually transmitted?
No, tuberculosis is not sexually transmitted, however, if you spend enough time with an infected individual, you may still be infected via airborne droplets when they speak, laugh, cough, sneeze, or sing.
Ministry of Health. (2022, March 24). Update on tuberculosis situation in Singapore. Retrieved from Ministry of Health Singapore: https://www.moh.gov.sg/news-highlights/details/update-on-tuberculosis-situation-in-singapore-2022
Claudia Carranza, S. P.-S.-M. (2020). Diagnosis for Latent Tuberculosis Infection: New Alternatives. Frontiers in Immunology.
Knut Lönnroth, E. J. (2009). Drivers of tuberculosis epidemics: the role of risk factors and social determinants. Social Science and Medicine, 2240-2246.