QuantiFERON TB test

Overview

The QuantiFERON-TB Gold test is a blood test that checks if your immune system has been exposed to the bacteria that cause tuberculosis (TB). It helps doctors find a TB infection that may be hiding in your body without making you sick (called latent TB) or to help diagnose active TB.

Yes, the QuantiFERON test is widely used around the world, especially in countries like the UK where the BCG vaccine is given.

It is used for people who need TB screening, such as those who have been in close contact with someone with active TB, people with weakened immune systems, healthcare workers, and people who have recently moved from places where TB is common.

Symptoms

Common symptoms

• A persistent cough lasting more than 3 weeks
• Unexplained weight loss
• Night sweats
• Fever or chills
• Coughing up blood or phlegm

Symptoms in children

• Poor weight gain or failure to grow
• Persistent tiredness
• Swollen lymph nodes
• Cough that does not go away

Symptoms in older adults

• Loss of appetite
• Low energy or fatigue
• Confusion or memory problems
• Cough that may be less noticeable

Causes

Main causes

• Infection with the bacterium Mycobacterium tuberculosis, which causes TB.

Risk factors

• Close contact with someone who has active TB
• Living or working in crowded conditions
• Weakened immune system (e.g., from HIV, diabetes, or certain medications)
• Recent travel to or living in a country where TB is common
• Being a healthcare worker who cares for TB patients

When to see a doctor

See a doctor urgently if:

• If you have symptoms of active TB, such as a persistent cough, night sweats, weight loss, or coughing up blood.

Book a routine appointment if:

• If you have been in close contact with someone diagnosed with TB
• If you have a weakened immune system and need screening
• If you are required to have a TB test for work, school, or travel

Diagnosis

The QuantiFERON test is done by taking a sample of your blood, just like any other blood test. It is used instead of the TB skin test, especially if you have had the BCG vaccine.

Tests that may be done

• QuantiFERON-TB Gold blood test
• If the blood test is positive, your doctor may also order a chest X-ray or a sputum (phlegm) test to check for active TB.

What to expect at your appointment

A healthcare worker will draw a small amount of blood from your arm. The blood is sent to a lab where it is mixed with TB proteins. If your immune system has seen TB before, your blood cells will release a chemical called interferon-gamma, which the test measures. Results are usually ready within 24 hours.

Treatment

If your QuantiFERON test is positive, it means you have been infected with TB bacteria. Your doctor will decide if you have latent TB (inactive) or active TB. Treatment is different for each, but both are very effective.

Self-care at home

• Take all medications exactly as prescribed, even if you feel fine.
• Keep all follow-up appointments with your healthcare team.
• Eat a balanced diet to support your immune system.
• Avoid alcohol and smoking, as they can interfere with treatment.

Medical treatments

For latent TB, treatment usually involves taking one or more antibiotics for 3 to 9 months to prevent the infection from becoming active. For active TB, a combination of several antibiotics is taken for 6 to 9 months. Your doctor will decide the best plan for you. Always follow your doctor’s advice and complete the full course of treatment.

When is surgery considered?

Surgery is rarely needed for TB. In very rare cases, it may be used to remove damaged parts of the lung or to drain fluid from around the lungs.

Living with this condition

If you have latent TB, you can live normally and infect no one, but you need to complete treatment to prevent active TB. If you have active TB, you may need to stay home from work or school for a few weeks until you are no longer contagious. Your doctor will tell you when it is safe to be around others.

Lifestyle tips

• Get plenty of rest while your body recovers.
• Avoid alcohol and smoking, as they can make treatment less effective.
• Take your medication at the same time each day to build a routine.

Diet and exercise

Eat a healthy diet with plenty of fruits, vegetables, and protein. Gentle exercise, like walking, can help you feel better, but rest when you are tired.

Mental health and emotional wellbeing

A TB diagnosis can be stressful. You might feel anxious or isolated. It is important to talk to your healthcare provider or a counsellor if you have these feelings. Help is available.

Prevention

TB can be prevented by avoiding close contact with people who have active TB, and by treating latent TB before it becomes active. Good ventilation and wearing masks in healthcare settings also help.

Vaccines

The BCG vaccine is given in many countries, including the UK, to protect against severe forms of TB in children. It does not always prevent infection, but it can reduce the risk.

Screening programmes

Routine screening with the QuantiFERON test is recommended for people at high risk, such as healthcare workers, people who have been in close contact with TB, and those with weakened immune systems.

Complications

If left untreated

• Latent TB may develop into active TB, which can cause serious lung damage.
• Active TB can spread to other parts of the body, such as the brain, kidneys, or spine.
• Untreated active TB can be life-threatening.

Long-term outlook

With proper treatment, most people with TB recover fully. Treatment is very effective, and the outlook is excellent if the infection is caught early and the full course of medication is taken. You can expect to get back to your normal life.

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