Tuberculosis: What You Should Know

Tuberculosis

Tuberculosis (TB) is an infectious disease that has affected humans for thousands of years.

Despite advances in medicine, it remains one of the leading infectious causes of illness and death worldwide. In the UK, around 9 in every 100,000 people develop TB each year. Understanding what TB is, how it spreads, and how it can be prevented or treated is vital for protecting both individual and public health.

What is tuberculosis?

TB is caused by a bacterium called Mycobacterium tuberculosis. Most cases affect the lungs (pulmonary TB), but the infection can also spread to other parts of the body such as the lymph nodes, spine, brain, or digestive system (extrapulmonary TB).

TB infections are classified as either:

• Latent TB – the bacteria are present in the body but inactive. No symptoms are seen, and the person is not contagious. However, latent TB can later progress to active TB.

• Active TB – the bacteria are multiplying, symptoms appear, and the infection can spread to others.

How TB spreads

TB spreads through droplets released into the air when someone with active pulmonary TB coughs, sneezes, laughs, or sings. Unlike the flu, TB is not highly contagious after short contact. Instead, it usually spreads after prolonged, close contact with someone who is infectious.

Importantly, TB does not spread through food, drink, utensils, clothes, or sexual contact.

When inhaled, the bacteria can settle in the tiny air sacs of the lungs (alveoli). If the immune system fails to contain the bacteria, the infection develops into active disease, which may spread further.

Risk factors for TB

While anyone can develop TB, some factors increase risk:

• Weakened immune system (e.g. HIV/AIDS, leukaemia, chemotherapy, organ transplant medication)

• Close contact with someone with active TB

• Living or travelling in areas with high TB prevalence (e.g. South-East Asia, sub-Saharan Africa, parts of Eastern Europe)

• Poor nutrition or crowded living conditions

Symptoms

Pulmonary TB most often presents with:

• A persistent cough lasting more than three weeks

• Coughing up phlegm or blood

• Unexplained weight loss

• Loss of appetite

• Fever and night sweats

• Fatigue

Extrapulmonary TB symptoms depend on the site of infection — for example, spinal TB may cause back pain, while lymphatic TB can cause swollen glands.

Diagnosis

Doctors use a combination of medical history, physical examination and tests:

• Chest X-ray – to look for lung damage

• Sputum tests – to check for TB bacteria

• Bronchoscopy – if sputum samples cannot be obtained

• Mantoux skin test – to check if TB infection has ever occurred

• IGRA blood test – now more commonly used than the skin test

For suspected extrapulmonary TB, CT or MRI scans and tissue biopsies may be needed.

Vaccination

The BCG vaccine (Bacillus Calmette-Guérin) is offered in the UK to newborns, children, and adults at higher risk of TB. It provides strong protection when given in childhood and moderate protection in adulthood. It is particularly important for those travelling to or living in high-TB regions or working in healthcare.

Treatment

TB is curable with antibiotics, but treatment takes time:

• Latent TB – usually treated for 3 months

• Active TB – requires at least 6 months of treatment

The standard regimen includes four antibiotics: Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol. After two months, usually only Rifampicin and Isoniazid are continued. In some cases, treatment extends up to nine months.

It is essential to complete the full course. Stopping early increases the risk of relapse and drug-resistant TB, which is much harder to treat.

Drug-resistant TB

In the UK, around 1 in 10 TB cases are resistant to at least one of the first-line drugs. These cases require longer treatment and additional medications such as Bedaquiline or fluoroquinolones. Multidrug-resistant and extensively drug-resistant TB, though rare, are global concerns and require specialised care.

Preventing TB spread

If you are diagnosed with active pulmonary TB, you will need to self-isolate for at least 14 days after starting treatment to prevent transmission. Wearing a mask around others until treatment begins is also recommended.

Once antibiotics have been taken for two weeks, most patients are no longer infectious and can resume daily activities.

Long-term complications

Without treatment, TB can cause lasting damage. Pulmonary TB may result in lung cavities and chronic breathing difficulties. Spinal TB can weaken or destroy vertebrae, sometimes requiring surgery.

FAQs

1. Can TB be cured?

   Yes, TB can be cured with a full course of antibiotics.

2. Can TB come back?

   If treatment is not completed properly, TB may return or develop resistance.

3. Is TB still common in the UK?

   Cases have declined over recent decades, but TB remains a public health issue, especially among people with links to countries where TB is more common.

4. Who should see a doctor?

   Anyone with a cough lasting more than three weeks, unexplained fever, night sweats, or weight loss should see their GP. Early diagnosis greatly improves outcomes.

References

1. Kumar, V., Abbas, A. K., Aster, J. C. Robbins and Cotran Pathologic Basis of Disease. 10th Edition. Elsevier, 2020.

2. Walker, B. R., Colledge, N. R., Ralston, S. H., & Penman, I. D. Davidson’s Principles and Practice of Medicine. 23rd Edition. Elsevier, 2018.

3. Murray, J. F., & Nadel, J. A. Textbook of Respiratory Medicine. 7th Edition. Elsevier, 2021.

4. Raviglione, M. C. Tuberculosis: The Essentials. 2nd Edition. Informa Healthcare, 2009.

5. World Health Organization. Global Tuberculosis Report 2023. WHO, 2023.