In the
beginning there was TB. Then we got MDR TB. And now we have the latest
incarnation of the "Captain of all these Men of
Death", namely, XDR Tuberculosis.
Tuberculosis (TB) has been the greatest killer ever known to man.
Even today it kills more people than AIDS, malaria and other tropical
infections put together. It dates from antiquity and mention of it is
found in the writings of ancient Egyptians and other ancient
civilizations. The English writer John Bunyon better known to us as the
author of Pilgrim's Progress aptly described tuberculosis as the
Captain of all these Men of Death as
there was no effective treatment for this disease before the 1940s.
Tuberculosis does not respect the class of people or national
boundaries. Some of the famous people that were victims of TB include
John Keats, all three Bronte sisters, Lord Byron, Shelley, D. H.
Lawrence, John Calvin, Chopin, St. Thérèse of Lisieux, actress Vivien
Leigh (who can forget Scarlett O'Hara of Gone with the Wind!) Alexander
Graham Bell and ironically, René Laënnec the inventor of the
Stethoscope.
Though
Robert Koch discovered the tubercle bacillus, the germ that causes
tuberculosis, in 1882, it was a chance discovery of the antibiotic
Streptomycin in the 1940s by a soil microbiologist named Selman Waksman
that gave us the first drug against the disease. Soon, other drugs
followed and the use of combination drugs (combining two or more
different anti TB drugs) saw a dramatic drop in the number of cases of
tuberculosis. More than 95 percent of cases of TB
can now be cured with the correct use of combination
drugs.
But just
when everybody thought that the battle against TB was over, disturbing
news about the rising incidence of TB began to come from all over the
world. It was found that a great many people failed to recover from the
disease despite using anti-TB drugs. The TB germ was getting resistant
to the drugs! This was the genesis of Multi-drug
Resistant Tuberculosis (MDR TB)
What is MDR Tuberculosis?
This is
tuberculosis caused by the TB germ that has become resistant to two of
the most powerful and commonly used drugs, namely, INH and Rifampicin.
These two drugs form the back-bone of TB treatment and therefore
resistance to these drugs results in treatment failure.
What is the cause for the emergence of MDR
TB?
Inappropriate use of the anti-TB drugs is the single most common
cause of emergence of MDRT.
For treatment to be effective, the drugs
should be taken at the right doses for at least 6 to 9 months (sometimes
for a longer period, depending upon the severity of the disease). But
quite often the patient stops treatment on his own after just 2 or 3
months because he feels better. THIS IS WRONG! BY
DOING THIS THE PATIENT DOES GREAT HARM TO HIMSELF AND TO THE
COMMUNITY. It takes a full 6 to 9 months of drug therapy for
effectively killing of all the germs in the patient's body and effect a
cure. When treatment is stopped prematurely, the germ population is only
suppressed and not completely killed. These germs that linger in the
body of the patient become reactivated at a later date causing a
recurrence of the disease. As if this is not bad enough, these germs
that were initially responsive to the drugs now become resistant, that
is, the drugs are no longer able to kill these germs! This is the
genesis of MDR TB.
Another reason for the emergence of MDRT is using
drugs in low doses or using only one drug at a time. As mentioned
earlier anti-TB drugs are always used in combination and never as single
drugs.
Are there any other causes for MDR
TB?
Another very important reason for the emergence of MDR
TB is the co-existence of HIV / AIDS. When a person with AIDS develops
tuberculosis the chances of the germ becoming multi-drug resistant is
high.
Why is MDR TB bad news?
MDR Tuberculosis is
bad because treatment of this requires more powerful, more toxic and
more expensive drugs for a longer period of time, something which a
country like ours cannot afford. Besides, the success rate of treatment
is also lower compared to that of the conventional disease.
At
present, it is estimated that about 4 percent of all new cases of TB in
Asia, Africa, Eastern Europe and Latin America are MDR.
What is XDR Tuberculosis?
XDR TB (Extensive
Drug Resistant or Extremely Drug Resistant TB) is a form of TB caused by
germs that are in addition to being resistant to the first line drugs
(INH and Rifampicin) are also resistant to at least 3 of the 6 classes
of second line drugs. In practice this means that
these cases are virtually untreatable, taking us back to the
pre-antibiotic era. It puts us back to the early twentieth century as
far as treatment of these cases go.
Where are these XDR TB cases found?
XDR TB
has been reported from all parts of the world. But it is particularly
common in Asia and countries of the former Soviet Union. In America 4%
of cases of MDR TB are also XDR TB. In Latvia this figure is 19
%!
What are the consequences of XDR TB?
As
mentioned earlier these cases are virtually untreatable. In a recent
outbreak of tuberculosis in an HIV positive population of South Africa,
of the 544 patients studied, 221 had MDR TB. Of the 221 MDR TB cases 53
were XDR TB. 52 of these 53 cases died within 25
days despite adequate therapy! These figures (though they are
pallindromic) tell us a grim tale! Unless we treat TB appropriately now
we are in for very big trouble and WE HAVE NO ONE
TO BLAME BUT OURSELVES if we land ourselves in the
pre-antibiotic age.
