Newsgroups: sci.med
Subject: Re: Tuberculosis
Date: Wed, 30 Dec 1992 12:59:07 -0600

From  cs.rochester.edu!fulk
To:   Doug.Platt@f595.n106.z1.fidonet.org

In article <725297239.AA00335@f-454.fidonet.org> you write:
>A few weeks ago, a friend told me that his girlfriend (who lives with
>him) had been diagnosed with "borderline tuberculosis."
>First, I've never heard of anyone being "borderline" with this disease.
>Is that possible?
 
Although I've had some rather unfortunate experiences with TB in friends
lately, I haven't heard of this diagnosis.  Perhaps the diagnosis is
"inactive TB."
 
>Second, since he told me this, I've been hesitant to visit them.  I'm
>running out of excuses why I can't come over.  Is it as contagious as
>I think it is.  Am I being overly cautious by not visiting there?
 
If the case is inactive, you probably don't have anything to worry about.
If her case is active, however, you should be somewhat worried.  TB is not
as contagious as a cold, but it is contagious.  To give you an idea: one
of our students had a mild active case (that he didn't recognize or treat)
for part of a year; his office mate may have been infected (or may have
brought the disease from Eastern Europe, we don't know which); no one
else in the department has caught it.

TB is an interesting disease.  It tends to alternate between active and
inactive modes.  In the inactive mode, the bacilli are walled into lung
cysts (the official name escapes me now), which are the primary findings
on a chest x-ray.  In the active mode, the bacilli spread into the lungs,
destroying lung tissue and getting coughed up in sputum.  Treatment is
with two antibiotics, usually isoniazid and rifampin; isoniazid (INH)
kills most of the bacilli, while the rifampin gets any INH-resistant germs.
Treatment takes a year, because the bacilli are largely inaccessible
in the cysts.  One hopes that the case activates one or more times
during the year.  One hopes that a patient with a temporarily inactive
case doesn't stop his medication because he feels better.

Notes:

Tine tests (the little pricker they use in school) suffer fairly high
false negative and positive rates.  There is another test (again the name
escapes me) that is much better; it involves a subcutaneous injection.

Both inactive and active cases test positive.

BCG vaccine, which is often given in the former Soviet Bloc and in some
parts of the third world, often, but not always, produces a positive test.

X-rays are an important part of tuberculosis diagnosis, but cannot
_reliably_ distinguish an active from an inactive case.  (Source: three
radiologists I asked this question of, plus the NYS and Monroe County
health departments.  This was very important to someone once.)

The gold standard for activity and transmissibility of TB is a sputum culture.

It is considered reasonable to treat an inactive case with 6 months of INH
only.  I tend to think that this is short-sighted (a non-medical opinion).

INH is very hard on the livers of people over 40 or so.  If someone in
that age range has an inactive case, it will usually be left untreated.
I understand the tradeoff; I just hope that these people see the doctor
every time they get a cough.

The TB bacillus can invade other tissues than the lung.  However,
pulmonary TB represents the majority of cases.

TB could be eliminated, a` la smallpox, by a concerted global effort of
case identification, vaccination, and treatment.  The effort would be
greater than was required for smallpox, and the time to success would
be longer.  But...

TB morbidity is increasing at about 15%/year in the US; most of this
increase is NOT due to AIDS patients.

The Los Angeles Health Department, in 1990, did not have enough medicine
for the indigent people with active TB; much less did it have the social
workers to make sure they kept taking their medicine for a year.  As a
result, there were thousands of poor people in the streets of Los Angeles
with active TB, spreading it out to even more people.  May Ronald Reagan
catch TB in Hollywood.

You may have seen some rather nice public service ads from the Will Rogers
Institute.  They used to run a TB sanatorium in upstate NY; it closed after
the last patient died, twenty or thirty years ago.  The success of the
IHN-rifampin treatment, and public health measures, had eliminated the
threat of TB epidemics.  Pressure your congressman for a strong public
health response to the present increase, so that the Will Rogers folks
can go on making those ads and don't have to reopen the sanatorium.

I can tell much more, but I hope this answers your questions as well as
it pushes part of my political agenda.

Mark
-- 
Mark A. Fulk                    University of Rochester
Computer Science Department     fulk@cs.rochester.edu