What is tuberculosis?
Tuberculosis (TB) is a disease caused by an infection with the bacteria
Mycobacterium tuberculosis complex.
During
the 19th century, up to 25 per cent of deaths in Europe were caused by
this disease. It used to be called the 'white death' as opposed to the
Black Death caused by plague.
The death toll began to fall as
living standards improved at the start of the 20th century, and from the
1940s, effective medicines were developed.
However, there are now
more people in the world with TB than there were in 1950, and 3 million
individuals will die this year from this disease – mainly in less
developed countries.
It is estimated that any one time, up to a third of the world's population have been infected with TB.
The
disease is more common in areas of the world where poverty,
malnutrition, poor general health and social disruption are present.
In the UK, too, the number of TB cases is again rising.alcholic, hiv positive person, some recent immigrants and healthcare workers are at increased risk.
The
disease is most commonly found in places such as hostels for the
homeless, prisons, and centres for immigrants arriving from areas with
high rates of hiv infection or inadequate health provision.
What parts of the body are affected by tuberculosis?
Lung
TB: TB commonly presents as a disease of the lungs. However, the
infection can spread via blood from the lungs to all organs in the body.
This
means that you can develop tuberculosis in the pleura (the covering of
the lungs), in the bones, the urinary tract and sexual organs, the
intestines and even in the skin.
Lymph nodes in the lung root and on the throat can also get infected.
Tuberculous meningitis is sometimes seen in newly infected children. This form of the disease is a life-threatening condition.
Non-lung TB is an important cause of skin, bowel and gynaecological problems.
How do you catch tuberculosis?
Lung TB: the bacteria that cause the disease are inhaled in the form of microscopic droplets that come from a person with tuberculosis.
When
coughing, speaking or sneezing, the small droplets are expelled into
the air. They dry out quickly, but the bacteria itself can remain
airborne for hours.
However, the tuberculosis bacteria are killed when exposed to ultraviolet light, including sunlight.
Non-Lung
TB: infected milk or dairy products can cause the mycobacterium to set
up infections in the gastro-intestinal tract and also affect the
reproductive systems in men and women.
How does the disease develop inside the body?
Lung
TB: after the tuberculosis bacteria have been inhaled they reach the
lungs and, within approximately six weeks, a small infection appears
that rarely gives any symptoms. This is called a
primary infection.
After
this, the bacteria can then spread through the blood. If you have a
healthy immune system, in most cases the infection will remain dormant
without doing any obvious harm.
Non-Lung TB: a similar process as above but the route of entry may be through the gut.
Months
or even years later, however, the disease can become reactivated in
different organs if the immune system is weakened. The lungs are the
favourite place for the illness to strike.
What are the symptoms?
Typical signs of tuberculosis are:
- chronic or persistent cough and sputum production. If the disease is at an advanced stage the sputum will contain blood
- fatigue
- lack of appetite
- weight loss
- fever
- night sweats.
Tuberculosis can mimic many forms of disease and must always be considered if no firm diagnosis has been made.
Other non-tuberculous mycobacteria found in soil and water can cause disease in susceptible patients with a history of cystic fibrosis, chronic lung damage, alcoholism and immunosuppression (suppression of immune responses by a disease or drugs).
These atypical mycobacteria can be present as colonising organisms without necessarily causing disease.
When should I see a doctor?
If you have a persistent cough
with sputum for more than three weeks or you see blood in your sputum
or unexplained weight loss or unexplained night ,sweats, you should
contact your doctor.
How does the doctor make the diagnosis?
Lung TB: the doctor cannot always hear enough to make a diagnosis by just using a stethoscope.
If your physician suspects there is something wrong and that it is not just a cold, you may be referred to an outpatient department for people with lung diseases or to an X-ray department.
The chest x ray examination is the most important test. If there are changes in the lungs, a sample of sputum will be sent for microscopic element and culture.
Culture
of tuberculosis bacteria will take 4 to 12 weeks. For this reason, it
takes some time before an accurate diagnosis is possible.
Quicker methods using DNA techniques are now available, and a skin reaction Mantoux test can sometimes be a great help.
In this test, tuberculin, which is a substance extracted from the tubercle bacteria, is injected into the skin.
If
the skin shows a strong reaction after 72 hours, it means there is
hypersensitivity to tuberculin protein acquired either by a previous BCG vaccination, or possibly due to an active infection.
Non-Lung TB: The diagnosis may only be made after surgical exploration.
In
both lung and non-lung TB, we now have blood tests that can tell if you
are on of the two-thirds in the world never infected (a negative test).
If
the test is positive you either have active TB (which may be infective
to others) or you have latent TB (which may become active if your immune
system is made less effective by steroids, age or HIV).
Are there other diseases with similar symptoms?
Lung TB: bronchitis, pneumonia, smoker's lung and lung cancercan all show practically the same symptoms as tuberculosis.
If
tuberculosis is suspected, tests will need to be done to rule out the
presence of these other diseases. Examination of sputum will usually
include a check for cancer if the chest X-ray raises any suspicion of
this type of diagnosis.
Non-Lung TB: can be confused with cancers,
it can be a cause of a wide range of gastro-intestinal symptoms,
infertility and unusual skin lesions.
Where can I get a vaccination against tuberculosis?
In
the UK, BCG vaccination (with live but weakened tubercle bacteria) is
no longer routinely given to all children of secondary school age.
The highest rates of the disease occur in particular risk groups and it now makes more sense to target BCG vaccination for people who are at greatest risk of the disease.
The vaccine is now recommended for:
- infants
under one year of age living in areas where the incidence of TB is 40
cases per 100,000 people or higher (technically this applies to London,
UK)
- infants under one year of age whose parents or grandparents
were born in a country with an incidence of TB of 40 cases per 100,000
people or higher
- children with risk factors for TB who have not previously been vaccinated
- new immigrants from countries with a high incidence of TB who have not already been vaccinated
- contacts of people diagnosed with TB affecting the lungs
- health
care workers, veterinary staff, staff working in prisons, residential
homes, shelters for the homeless or hostels for refugees
- people intending to live, travel or work in countries with a high incidence of TB for more than a month.
Vaccination
is thought to reduce the likelihood of subsequent pulmonary TB and
effectively prevents varieties of blood-borne tuberculosis such as
miliary TB or tuberculosis meningitis in infants, which can be difficult
to diagnose in time and can cause devastating damage.
How is tuberculosis treated?
Today, treatment involves three or four different kinds of antibiotic given in combination over six to nine months.
Multiple
medicines are necessary to prevent the emergence of resistance, which
would lead to treatment failure and the nightmare of multiple
drug-resistant organisms.
Single medicines must
never
be added to a failing treatment regime. Therapy should be directed by a
chest physician who will have specialist knowledge of the complications
and side-effects of TB medicines.
Attention to the details of
treatment are vital. The main cause of treatment failure is
non-compliance with what is perceived as a demanding and prolonged
programme of therapy.
Those patients who are microscopy or smear
positive are infectious and, if possible, should avoid contact with
other people for two weeks.
Patients do not require hospital
admission in order to start treatment. Other patients with a lower
bacterial load are smear negative but culture positive on testing. These
patients are not as infectious but should still have therapy along
conventional lines.
Chemoprophylaxis with a single medicine, isoniazid,
may be given for 6 to 12 months with the aim of preventing future
disease in individuals who show no evidence of disease, but have a
strongly positive tuberculin skin test and no evidence of previous BCG
vaccine to explain the positive skin test.
pregnent women with TB must be treated urgently as the disease may progress rapidly with high risk to both mother and baby.
Is it possible to become resistant to the medicine?
Yes, if medication is not taken every day or as prescribed by the doctor.
In some parts of the world there are problems with resistance to medication and even multi-drug resistance.
This
is a very serious situation, which has been experienced on a large
scale in parts of Africa, the Baltic States, many East European
countries, certain American cities and in areas of the developing world.
XDR-TB,
is an abbreviation for extensively drug-resistant tuberculosis (TB)
(this form of TB is resistant to at least four of the core anti-TB
drugs).
MDR-TB involves resistance to the two most powerful
anti-TB drugs, isoniazid and rifampicin. MDR-TB and XDR-TB both take
much longer to treat than ordinary TB, and require the use of anti-TB
drugs, which are more expensive and have more side effects than the
normal TB drugs.
If there are problems with patients not taking
their medicines, it may be necessary to arrange supervision either in a
hospital or at home with a nurse. This programme is known as DOTS
(directly observed treatment, short-course) and is recommended by the
World Health Organisation (WHO).
How can treatment be controlled?
An
undetected infectious TB victim will, on average, infect another 10
cases in a year, each of whom could transmit the disease in turn.
According
to the WHO and the international tuberculosis union IUATLD, all
countries should have a national tuberculosis programme and authorities
should also be notified about patients who have been diagnosed with TB.
The
treatment itself is prescribed under the supervision of chest clinics
where they make sure that the patient has correctly taken a curative
course of treatment.
Negative culture from sputum in 6 to 12 months from the moment of the diagnosis indicates a cure.
The
clinics make sure that the environment in which the patient lives is
also carefully examined. All family members will be required to undergo
chest X-rays. Sometimes, the patient's workplace will also be examined.
What are the world's highest-risk regions?
Infection is possible anywhere, but tuberculosis is especially prevalent in sub-Saharan Africa and in Southeast Asia.
The disease is more common in Eastern Europe than Western Europe, and Scandinavia has the lowest number of cases in the world.
Is HIV/AIDS associated with tuberculosis?
Yes. In certain African countries and many parts of Southeast Asia, HIV is becoming more and more endemic.
Where
tuberculosis is also endemic among the population, a weakened immune
system will increase the risk of getting tuberculosis.
This is an extremely worrying situation and the WHO and the IUATLD are doing all they can to prevent the disease from spreading.
Can tuberculosis be prevented?
TB is reduced with better housing and less over-crowding.
The most important step is to find, isolate and treat all disease carriers until they are no longer an infective risk to others.
It
is always advisable not to get too close to people who are coughing;
equally, people with a cough should be aware of those around them and
try not to cough or spit near them.
Good advice
If you
travel in countries where tuberculosis is a problem, get travel health
advice about BCG vaccination and avoid socialising with people who have a
persistent cough.
Make sure that you eat well and enjoy plenty of sunlight and exercise.
Seek medical attention:
- if you develop a cough that persists for more than three weeks
- if you see blood in your sputum
- if you have unexplained weight loss or unexplained night sweats.
Cystic fibrosis, or 'mucoviscidosis', is a hereditary disease. A defective gene results in an inability to transport salt in certain kinds of cells in the lungs and in the pancreas. It is the most common hereditary disease in Western Europe.
