Tuberculosis (TB)

Tuberculosis is caused by a slow-growing bacterium, Koch's bacillus. It settles in the lungs most of the time, but it can take hold in almost any organ. The disease is ancient and thickly wrapped in fears, and the fears are usually what gets in the way: that it is an illness of the destitute, that you can catch it on a bus, that nobody recovers from it. None of the three is true. Anyone can develop TB, a passing encounter almost never leads to infection, and tuberculosis is curable. There is one caveat, and it is a serious one: treatment runs for months, and it must not be stopped part way.

What should make you look twice

TB of the lungs unfolds slowly, over weeks, which is why it is so easily put down to a cold that dragged on, to tiredness or to smoking. People can rarely name the day they fell ill.

• a cough lasting more than three weeks, dry at first and later bringing up phlegm;
• streaks of blood in the phlegm; even once is reason to be investigated rather than wait for it to happen again;
• night sweats heavy enough that the bedding has to be changed;
• a low fever, around 37.2 to 37.5 °C, that climbs towards the evening and stays for weeks;
• weight falling away on its own, with no diet and no change in eating;
• weakness and exhaustion that effort does not explain;
• loss of appetite;
• chest pain on breathing in deeply or coughing.

In children the picture is blurrier: they stop gaining weight, fall behind in growth, become listless and irritable, and there may be no cough at all. In older people and in anyone whose immune system is weakened the fever can also be absent, leaving only weakness and weight loss.

TB is not only a lung disease

In roughly one case in five the disease develops outside the lungs, and it is then recognised later, because the complaints do not point towards an infection.

• lymph nodes, most often in the neck: a node swells slowly over weeks, painless, and the skin over it may thin;
• bones and spine: constant back pain that does not ease with rest and worsens at night, together with weight loss and a low fever; left alone it destroys a vertebra;
• the membranes around the brain: headache building over days, fever, vomiting, drowsiness, a change in behaviour — the most dangerous form;
• the pleura: breathlessness and pain in the side as fluid collects;
• kidneys, bowel, abdominal lining, joints, larynx, skin — less commonly.

One point that takes a needless fear off the family: TB outside the lungs is not spread through the air. The only person who is infectious to others is one who releases bacteria in their phlegm, meaning the lungs or the airways are involved.

When not to wait

Call an ambulance — in Europe the single number is 112 — if someone with suspected or confirmed TB develops:

• a severe headache together with fever, vomiting and pain on looking at light;
• a stiff neck, so that the chin cannot be brought down to the chest;
• confusion, unusual drowsiness, a seizure;
• weakness in an arm or a leg, double vision;
• heavy coughing of blood — mouthfuls rather than streaks;
• sudden severe breathlessness or sharp chest pain.

The first four mean the infection has reached the membranes around the brain. That can be treated, but the outcome depends directly on which day treatment began.

No ambulance is needed, but see a doctor the same day, if a cough has run past three weeks, if weight is falling for no reason, if you sweat at night and an evening fever persists — or if you live with someone who has TB of the lungs and you have started to feel unwell.

How it is caught, and how it is not

The bacteria enter the air when someone with active lung TB coughs, sneezes or talks. Catching it takes breathing that air in for long stretches and repeatedly: sharing a home, sharing a small office, long journeys — weeks of close contact, not a minute in a lift.

Tuberculosis is not passed on through crockery, food, towels, bedding, clothes, money, door handles or handshakes. There is no need to set aside separate dishes for the person who is ill, and ordinary washing is enough for their things. After a couple of weeks of proper treatment they usually stop being infectious and go back to normal life long before the course ends.

The risk of falling ill after infection is higher in anyone whose immune system is weakened: with HIV, on medicines that suppress immunity, after an organ transplant, during chemotherapy. Poorly controlled diabetes, undernutrition, smoking, heavy drinking and crowded damp housing all add to it. Children under five are separately vulnerable, as the disease more often takes a severe form in them.

The BCG vaccine exists, and it works differently from what many people assume: it protects small children well against the most dangerous forms, miliary TB and TB meningitis, but it does not reliably shield an adult from TB of the lungs. Who receives it and at what age depends on how common TB is in the country — some vaccinate every newborn, others only children in at-risk groups. Check the national immunisation schedule where you live.

Infected but not ill

In most people who breathe the bacterium in, the immune system seals it inside a dense capsule. The bacterium stays alive but does not multiply and goes nowhere. This is called latent tuberculosis infection, and it is not an illness: there are no symptoms, the chest X-ray is clear, the person is safe to be around and needs no restrictions at home or at work.

Latent infection is not found from complaints but deliberately looked for: when the contacts of someone with TB are screened, and before starting treatment that suppresses immunity. A Mantoux test or a blood test will show it; both say only that the immune system has met the bacterium, not whether you are ill now — that is decided by imaging and examination.

Over a lifetime, latent infection turns into disease in about one person in ten, and usually at the moment the immune system falters for some other reason. This is why people at high risk are offered preventive treatment: one or two medicines for a few months. The course is shorter and easier to tolerate than treating the disease itself, and it cuts the chance of falling ill several times over.

How the diagnosis is confirmed

The starting point is a chest X-ray, which shows the characteristic changes; where the picture is unclear, a CT scan follows.

The central test, though, is the sputum. It is examined under the microscope, grown in culture, and always run through a molecular test, which finds the bacterial DNA within hours and at the same time detects resistance to the main drug. That matters because the whole treatment plan hangs on the answer. Culture takes weeks to grow, but it gives the full picture of what the bacterium is sensitive to.

If there is no sputum, or TB is suspected outside the lungs, other material is taken: fluid from the chest cavity, urine, a piece of tissue from a lymph node or bone, spinal fluid. The diagnosis rests on imaging, tests and examination taken together, never on a single result.

Treatment is long, and stopping it is the mistake

TB is treated with several anti-tuberculosis antibiotics at once: none of them manages alone. For the first couple of months there are more medicines, after which the regimen is reduced. The minimum course is six months, and considerably longer where the membranes around the brain or the bones are involved, or where the strain is resistant. For TB of the brain membranes and of the sac around the heart, corticosteroids are briefly added to the antibiotics.

People feel better quickly, usually within two to four weeks. The cough settles, the fever goes, appetite returns, weight comes back and they feel well. That is the most dangerous moment of the illness. It is precisely then that treatment is most often abandoned, because carrying on swallowing tablets seems pointless.

Here is what happens next. The vulnerable bacteria die first, and they are the ones causing the symptoms. What survives is the toughest and slowest-dividing, the last to be reached by the drugs. Break off the course and the survivors start growing again, and their offspring are no longer sensitive to the medicines that were only half taken. This is how drug-resistant tuberculosis arises: it takes a year or more to treat, with different and far harsher medicines, and not everyone recovers. A resistant strain also passes to other people ready-made, so whoever catches it starts out with the resistant disease.

Hence the rule: finish the course exactly as prescribed, even once everything has cleared. If side effects get in the way — nausea, a rash, yellowing of the skin or the whites of the eyes, dark urine, deteriorating vision, numbness in the feet — do not stop on your own; contact your doctor the same day, because the regimen can nearly always be adjusted. If remembering is hard, or the medicines are unaffordable, say so plainly: support programmes exist for exactly that.

Online consultation

Everything around the diagnosis is well suited to a consultation online. The doctor will listen to the story of the cough and the weight loss, say whether it warrants investigation and where to start, go through an X-ray and test results you already have, and make sense of a Mantoux or blood test in someone who has been in contact. They can explain what the prescribed regimen is for and how long it runs, discuss what to do about side effects and how to keep the course on track, and advise on what is needed at home and when the household should be screened too. Signs that the membranes around the brain are involved, and heavy coughing of blood, call for an ambulance rather than a consultation.

This material is for information only and does not replace medical advice.