Tuberculosis (tubercle bacillus - TB) is an infectious
disease caused by Mycobacterium tuberculosis. Tuberculosis most commonly
affects the lungs (pulmonary tuberculosis), but other systems can be affected,
including the central nervous system, the lymphatic system, circulatory system,
the skeletal system and the genitourinary system.
This article discusses
Pulmonary tuberculosis is the form of the disease
that presents by far the greater risk, as it is highly infectious - spread by
airborne droplets - and this article will be confined to this form of the disease.
is tuberculosis usually found?
Tuberculosis is endemic throughout the world
- the World Health Organization has estimated that a third of the world's population
are living with tuberculosis.
As person to person spread is the usual route
of transmission, the disease has become associated with poverty, overcrowding,
poor living conditions; a predominantly urban disease. Advances in medicine, such
as the survival of many people with auto-immune conditions - and low resistance
to infection - has created a new group of people who are highly susceptible to
the disease; there are many cases of such individuals catching the infection while
In recent years, the emergence of drug-resistant forms of the
disease has further complicated the situation, and means that the general risk
of infection is rising.
How common is tuberculosis?
one third of the world's population probably carris the bacterium; but not all
these people will develop full-blown tuberculosis.
Up to nine out of ten
carriers of asymptomatic tuberculosis (latent infection) will not develop active
disease. But of those who do go on to 'active' disease, over half will die if
the disease is untreated. In 2004, almost fifteen million people had active tuberculosis;
nine million new infections were diagnosed, and almost two million people died,
mostly in developing countries.
How is tuberculosis
Tuberculosis is spread by droplets which are expelled when
an infected person exhales (including cough, sneezes, and speaking), and another
person inhales the bacteria. There is only a risk with open pulmonary tuberculosis,
when the infected person has the bacteria in their sputum.
is most at risk?
People living in high-density housing, institutions (such
as prisons). People with reduced immunity, such as those living with HIV, are
at serious risk. People living in poverty are at greater risk because of the greater
likelihood of contact with untreated disease, plus a likelihood of general ill
health with lower resistance to infection.
are the symptoms of tuberculosis?
A persistent cough is often an early
sign. it isusually a 'moist' cough, often large amounts of phlegm. Blood staining
may occur early, and significant blood with expectoration is a coomon feature
of more advanced disease.
As the disease spreads into the lymphatic system,
there may be swollen glands, especially in the neck.
Tiredness and listlessness
are common, usually accompanied by a loss of appetite. Severe weight loss is a
featrure of TB.
Night sweats may be profuse.
Pain on breathing in
may occur; this is caused by infection of the membranes surrounding the lungs
Before the disease process was fully understood, TB was known
as consumption; as the disease could accurately be described as consuming
What are the long term effects of
Long term effects include the possibility of latent disease
recurring later, effects of the disease itself, and effects of medicines and surgical
High dose medication can lead to liver damage, which can have
long term implications, but the major effect is on the lungs; lung capacity may
be severely reduced, with scar tissue further damaging lung function. In some
cases this may mean a permanent productive cough, with occasional haemoptisis,
and increased risk of lung infections.
Most people have little or no problems
post effective treatment for TB.
What is the mortality
rate for tuberculosis?
Tuberculosis remains the leading infectious disease
cause of death. bases on 2005 figures, there are over 1.5 million deaths per year,
some 24 per 100,000 population, though there is much variation around the world.
mortality is much higher among people who also have HIV, and this shows in the
statistics, particularly in Africa, where the diseases have progressed in tandem.
is tuberculosis diagnosed?
Because TB presents in many ways, medical evaluation
where pulmonary TB is suspected includes a medical history, a physical examination,
a chest X-ray and microbiological examination of sputum. It may also include a
tuberculin skin test, other scans and X-rays, and surgical biopsy.
history usually reveals a productive cough over at least three weeks, possibly
with chest pain, and hemoptysis, that is not responsive to conventional antibiotic
therapy. Systemic symptoms can include fever, chills, night sweats, appetite loss,
weight loss, and easy fatigability.
Prior TB exposure, infection or disease;
past TB treatment; demographic risk factors for TB; and medical conditions that
increase risk for TB disease, such as HIV infection, will assist in formaing a
Sputum is tested for acid-fast bacilli if the patient
is producing sputum; this provides a strong indication of the presence of TN;
a definitive diagnosis of tuberculosis is made by culturing Mycobacterium tuberculosis
from a specimen taken from the patient.
a treatment for tuberculosis?
Treat for most people with TB willinvolve
long-term drug treatment, and will almost always be at home, not in hospital.
Only where the patient is seriously ill, or has other problems requiring in-patient
treatment, will the hospital be necessary.
Standard drug therapy for active
TB will last for several months, involving combinations of anti-mycobacterial
antibiotics - isoniazid, rifampin, and pyrazinamide. Ethambutol or streptomycin
may also be used.
The treatment will be ineffective unless taken consitently
over a long period; indeed, the most common cause of treatment failure is failure
to comply with the drug regimen.
This is a very serious issue, as TB is
endemic among homeless, rootless and highly mobile populations of many cities,
causing the emergence of drug-resistant organisms.
Another important aspect
of tuberculosis treatment is contact tracing, as the disease is so contagious;
relatives, friends and even casual contacts may need to undergo skin tests and
chest x-rays or be asked for sputum specimens..
there a way to prevent infection?
Prevention of TB is a world poverty issue,
a world health issue and a local public health issue, and eradication will depend
on global co-operation, which is notable for it's verbal agreement and insufficient
TB is a preventable disease, and the most effective practical
measure against it is the efficient diagnosis and treatment of those who carry
the disease, before it can spread further.
Measures open to the individual
- Keeping the immune system healthy.
- Get tested regularly,
for those who have any disease that weakens the immune system or live or work
in a prison or any long-term care institution. Certain health care workers have
an increased risk of exposure to the disease.
- Consider preventive therapy
- If someone close to you is diagnosed, assist and encourage
them to stick closely to their treatment protocol.
who are diagnosed with TB:
- Cough into tissues, and dispose of these
- Cover your mouth. It will be two to three weeks before the treatment
stops the risk of contagion. Wearing an approved mask when people are around,
during the first three weeks, may help reduce the risk of transmission.
at home. Stay away from people. Don't go to work or school or sleep in a room
with other people during the first few weeks of treatment for active TB.
adequate ventilation. Open the windows whenever possible, day and night.
the entire course of medication, however well you may feel. This is the single
most important step you can take to protect yourself and others from TB. If treatment
is interrupted, or stopped too soon, TB bacteria may mutate into more therapy-resistant
strains which are at best much more difficult to treat, and at worst, fatal.
is the tuberculosis vaccine?
The vaccine contains a live, attenuated TB
bacteria, (Baceille-Calmette-Guerin - BCG).
# Vaccination against TB
is included in the childhood vaccination programme,
# Children are usually
vaccinated when 10 to 14 years, but children born in high risk communities like
certain immigrant groups should be vaccinated at birth.
# PHLS BCG vaccine
# BCG vaccination is considered in
# The vaccine gives a
small open wound, which heals over 4 to 6 weeks.
In the USA, people at
higher risk of TB have regular skin tests, and are treated if the skin test becomes
positive. As fewer than 10% of people infected with TB go on to develop the disease,
many people may be given a course of drugs unnecessarily.
is the protocol for tuberculosis vaccination?
In some countries, including
the UK, TB vaccination was routine for 15 year old school children. Despite the
rise of TB - including highly resistant strains - this practice was discontinued
in 2005 'allowing health resources can be more effectively targeted' - in other
words, to save money.
Who should get vaccinated
BCG vaccine is used for infants and adults in high-risk
communities, in most countries where the vaccine is available, and may be available
for previously unvaccinated travellers intending to stay in endemic areas for
Are there adverse reactions to the
The vaccine leaves a small open wound, which heals
over a few weeks, often leaving a scar.
be controlled environmentally?
While TB has many environmental factors;
more prevalent combined with poverty, or with HIV, more common in poorer countries
than richer ... TB is too contagious for containment to work as a disease control
measure, and in an age of cheap flights, it travels too easily and too fast.
can be learned from history?
Tuberculosis has been responsible not only
for millions of deaths, but also untold suffering among those who have lived with
the disease for years.
We should have learned that it is too bad a disease
to be allowed to spread again throughout the western world - not to mention too
bad a disease to be allowed to remain rampant in the developing world.
yet therapy-resistaant strains are indeed spreading, with morbidity and mortality
Further Information Sources
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Article written by Andrew Heenan BA (Hons), RGN, RMN