Tuberculosis, or TB, is a disease caused by bacteria called Mycobacterium tuberculosis. It usually affects the lungs (pulmonary tuberculosis), but other parts of the body can also be affected (extrapulmonary tuberculosis), such as the brain, lymph nodes, the kidneys, bones, joints. If not treated properly, TB can be a fatal disease. In most parts of the world, especially in developing countries, TB is a major cause of death and disability.

In 2009, the TB incidence rate was 38.6 per 100,000 residents (i.e 1,442 new cases) compared to 39.8 per 100,000 residents ( i.e 1,451 new cases) in 2008. Of the 1,442 new cases, 837 (i.e 58%) were 50 years old and above, and 1,040 (72.1%) were males. There were 125 relapsed cases among residents in 2009.

TB is spread by breathing in the air droplets containing the TB bacteria which is aerosolised when an infectious TB patient coughs or sneezes. TB, MDR-TB and XDR-TB are all transmitted the same way (see FAQ 14 and 15 for more information on MDR-TB and XDR-TB). Persons ill with TB are most likely to spread it to people who have close and prolonged contact with them. This includes family members, friends and co-workers.

Symptoms of TB disease depend on the area affected. Some people may not develop any obvious symptom. Some common symptoms of TB include:
• low-grade fever
• night sweats
• fatigue
• weight loss
• a persistent cough that lasts 3 weeks or longer
• chest pain
• coughing up blood or sputum

TB is a curable disease. When the TB is sensitive to the first-line anti-TB drugs, treatment takes between 6 to 9 months and more than 95% of patients are cured. However, patients must take all their medications as prescribed. Otherwise, the TB may recur or become resistant to anti-TB drugs.

People with, or suspected to have active TB disease should seek medical treatment as soon as possible. A chest x-ray and sputum diagnostic tests will be done to help detect TB disease. Patients diagnosed with TB are prescribed multiple drug therapy for at least six months.

To be effective in treatment of TB and prevent the risk of developing drug resistance, it is very important that patients follow their doctors' instruction to take the drugs exactly as prescribed and complete the whole course of treatment even if patients do not have symptoms anymore and start to feel better. This can also help prevent the spread of TB in our community.

The patient will generally become non-infectious after two weeks of TB treatment. He/she can return to work or school. However, he/she is not cured yet at this stage and must continue with the treatment until he/she has completed the whole course of treatment.

Stopping TB treatment prematurely before completion of the entire 6 to 9 months course of treatment can result in the patient becoming infectious again or developing TB strains which are resistant to treatment.

Directly Observed Treatment (DOT) is a process during which the TB patient takes each dose of medication under the direct observation of a health care worker to ensure that the correct dosage and combination of TB medications are taken.

Under DOT, the TB patients’ response and adherence to treatment is closely monitored, so that treatment failure, emergence of drug resistance and spread of the disease can be avoided.

A doctor who diagnoses a person with TB is required by law to notify the TB Control Unit (TBCU). The TBCU then conducts contact tracing to identify persons who may have been put at risk. Only persons who have had close and prolonged contact with persons suffering from active TB disease are at risk. These close contacts are given a skin test (Mantoux test) to assess whether they may have been infected. Reading of the Mantoux test results is done 48-72 hrs after the testing. Persons who tested positive for Mantoux test are then screened further by a Chest X-ray and given a clinical physical examination to exclude active TB disease. Persons with a positive Mantoux test but have no signs of symptoms of active TB disease have latent TB infection (LTBI). 

Contact tracing, Mantoux testing and chest X-rays carried out by the TBCU is provided free under the National TB Control Programme. 

Initial TB infection usually goes unnoticed. The TB bacteria can remain in the body without showing symptoms for years, sometimes decades. This is called latent TB infection (LTBI). LTBI is not a disease and persons with LTBI do not spread TB to others. About 10% of those with LTBI will develop active TB disease during their lifetime. Half of such persons do so in the first two years after acquiring the infection. The risk of developing active disease is higher in persons with weak immune system and young children under five years of age.

An anti-TB drug (isoniazid) is given as prophylaxis to persons with LBTI for 6 to 12 months to reduce the risk of developing active TB disease in the future. Isoniazid is able to reduce the risk of developing active TB disease by up to 90%. This means that the lifetime risk of developing active TB disease in persons with LBTI is reduced from 10% to 1% or less.

A major side effect of taking isoniazid is hepatitis (inflammation of liver). However, the risk is very low, at less than 1 per 1,000 for persons under 20 years of age. It is therefore a safe drug. Nevertheless, persons given isoniazid are given information on the symptoms of hepatitis so that they could seek further advice from the doctor if they do develop symptoms. Once they stop taking isoniazid, the liver recovers.

Isoniazid prophylaxis administered by the TBCU is provided free under the National TB Control Programme. 

Resistance to anti-TB drugs can occur when patients:
• fail to take their TB medicine regularly;
• fail to take all of their TB medicine as told by their doctor or nurse; or
• stop taking the TB medication before they complete the whole course of treatment.

The following persons are also at risk of developing drug-resistant TB:
• Persons who develop active TB disease again, after having taken TB medicine in the past;
• Persons who come from areas of the world where drug-resistant TB is common;
• Persons who have spent prolonged periods of time with someone known to have drug-resistant TB disease.

Multidrug-resistant TB (MDR-TB) is TB that is resistant to at least two of the best anti-TB drugs (isoniazid and rifampicin). These drugs are considered first-line drugs and are used to treat all persons with TB disease. When a person develops MDR-TB, second line anti-TB drugs will then have to be used. As these alternative drugs have weaker anti-TB activity, MDR-TB is very difficult to treat and treatment period is longer (between 18 and 24 months). Treatment success is between 50 and 70%. There were 3 cases of MDR TB in 2009.

Extensively drug-resistant tuberculosis (XDR-TB) is very rare, but is of grave concern because it is resistant to almost all drugs used to treat TB, i.e. the two best first-line drugs (rifampicin and isoniazid) as well as the two most important second-line drugs (fluoroquinolone and at least one of the three injectable drugs).

Patients with XDR-TB are left with treatment options that are much less effective and often have worse treatment outcomes. Treatment success can be as low as 30%. There have been no cases of XDR-TB in Singaporeans so far.

Patients with TB should check with their doctors if they are fit for travel. If they are fit for travel, they should ensure that they have adequate supply of medication for the entire duration of the trip. Patients who are still in the infectious stage of TB must postpone their trip until they are non-infectious and have been declared fit for travel by their doctors.