Few other diseases carry more public concern, and no
disease is more difficult to describe, than tuberculosis; as the tubercle germ
can attack may different parts of the body and manifest itself in many ways.
Furthermore, it is a widely spread disease, infecting not only humans but also
cattle, birds and reptiles. But here we are concerned with those types common to
man - the human and bovine (i.e. the type occurring in cattle which can be
spread to man by infected milk).
The tubercle bacillus is particularly hardy, so that when
coughed or spat out on the ground it continues to be infectious for a long time.
Infection is therefore caused by:
In other words, tuberculosis is caused by absorption
through either the lungs or the intestines; the former is common in adults, the
latter in children.
But there is a good deal more to the problem than this; we
know, for example, that over 90% of people in industrial countries have been
infected with TB in early life and have conquered the infection. So the question
arises: what conditions pre-dispose to TB - why do some people get over the
early infection and others not? There are two answers to this question: one is
certain - that those who are impoverished and do not get enough food are liable
to TB; the second is not so certain - that mental stress plays some part. Stress
causes a general reduction in immunity, predisposing the body to several
infections including TB.
In children, lung tuberculosis is not common, but
tuberculosis of the bones and glands is, as is also infection in the abdomen,
the kidney or spine, and, worst of all, tuberculous meningitis. These are often
of the bovine type from infected milk. Ordinarily, TB in children is less
serious than adult infections; but tuberculous meningitis used to be almost
invariably fatal until streptomycin was discovered.
Adult tuberculosis usually occurs in the lungs or the
pleura - the thin membrane surrounding the lungs. In younger people miliary
tuberculosis, which is a form of TB. blood-poisoning or septicaemia, is a very
serious condition, and the infection spreads throughout the whole body in a few
Lung infection begins gradually in someone who has
previously felt unwell. There may be cough, and later blood-stained sputum
(although blood which is coughed up does not necessarily prove that TB is
present). Whatever means of treatment is used, the struggle between disease and
patient is likely to be fairly long, but the outlook is now generally good. The
closure of the Swiss sanatoria is due partly to modern disbelief that air in one
place is better than that in another, but mainly to improved treatment.
Prevention depends on legal action ensuring
tuberculosis-free herds of cattle; on control of spread of the disease by those
“open” cases who carry germs in their sputum; on the use of vaccination in
childhood with the safe BCG vaccine.
Many methods are used in treatment: drugs, such as
streptomycin, isoniazid, and PAS, lung surgery, rest, and so on. TB is now a
fairly rare disease in developed countries, but there are increasing worries
that the emergence of antibiotic-resistant strains will lead to an upsurge in
its frequency in the developed western world. Like many aspects of third-world
healthcare provision, the money needed to make very serious reductions in the
number of people struck down by TB is relatively small, but the political will
do make the efforts has not been there. Sadly, as the HIV/AIDS infection takes
hold in greater numbers of people in the third-world, the ability to provide
safe effective vaccines, will be increasingly compromised.