Jenner
On Trial
Tom
Kerns
Chapter 1
Smallpox and AIDS: a comparison
With smallpox it was not at all
understood what the cause of the disease was, except that the
cause seemed to be something medical professionals called "the
smallpox poison." That phrase, usually referred to in its
Latin form, variola virus, meant literally "the smallpox
poison," and was said to be the cause of smallpox (variola).
The term "virus," in the centuries before Louis Pasteur
(18221895) and Robert Koch (18431910) with their discoveries
of microbes as the causes of infectious diseases, was used only
to mean the generic notion of "some poisonous force." The simple fact
was that no one knew just what caused smallpox. (Those today who criticize the
HIV-causes-AIDS thesis would say
that today also we do not know fully what the cause of AIDS is;
they then conclude from this that we should therefore not be looking
for an HIV vaccine, since we do not know that HIV is the cause
of AIDS.)
To make matters worse, the pathogenesis of smallpox, i.e., the
physiological mechanism(s) by which the "poison" caused
disease in the body, was also not understood. Microbiology, after
all, would not come into its own until late in the 19th century;
physicians in the 18th century, therefore, had no way of knowing
that some microbes (which they didn't even know existed ) grew
inside bodies and made them sick. Most AIDS researchers today
also candidly acknowledge that we do not fully understand the
pathogenesis of HIV disease and AIDS, and that there is still
much research to be done on this matter.
And yet, in spite of these two deficiencies - i.e., in spite of
understanding neither the causal agent of the disease nor the
pathogenesis of the disease - there was still a clearly focused
effort on the part of one man (an ultimately successful concerted
effort) to discover a method of artificially inducing an immunity
to smallpox. That is, despite these serious lacunae in the understanding
of smallpox, the search for a technique that would safely and
effectively immunize persons against the ravages of smallpox was
ultimately successful. This realization should probably buoy the
sometimes lagging spirits of those who hope to find an HIV vaccine
that will successfully immunize persons against AIDS and other
HIV disease.
Of course, the discovery of an artificially induced smallpox immunity
(a vaccine) came about only after, and as a result of, the clear
recognition of the existence of an already naturally-occurring
immunity to smallpox, i.e., an immunity acquired by actually contracting
the disease naturally. So far today with AIDS we do not have any
clear, convincing evidence of a pre-existing, naturally-occurring
immunity (though there are some promising possibilities already
being explored). Almost everyone (> 90%) who becomes infected
with HIV seems to eventually get sick and die of AIDS or other
HIV disease.
On the other hand, however, it may not be entirely true that we
have no cases of naturally-occurring immunity to HIV. Long-term
survivors of AIDS, and/or long-term non-progressors (i.e., persons
whose HIV infection does not seem to progress toward disease),
may turn out to be persons who are naturally immune to AIDS. Or
it may even turn out to be the case that virtually everyone who
becomes infected with HIV - during their first several years of
infection, when the virus is living and replicating (apparently
very prolifically) in the body without causing any clinical disease
- will turn out to be an example of a naturally-occurring immunity.
This possibility has been hinted at in recent studies which indicate
that the immune system successfully battles HIV for the first
several years, generating two billion new T-4 cells every day
to eliminate HIV from the body. The only reason, say these studies,
that the infection progresses so slowly is that the combatants
- HIV and the immune system - are so closely matched.
Any of these instances, or perhaps another one not yet discovered,
may turn out to be the example of naturally-occurring immunity
on which will be based the discovery of a successful AIDS vaccine.
In any case, despite significant differences between smallpox
and AIDS (e.g., their modes of transmission, latency periods,
effect on the immune system, etc.), there are a number of interesting
similarities.
One similarity, for example, is that the origin of both diseases
in humans is uncertain, but both seem to have probably originated
in animals and then crossed species to humans. (Cowpox, swinepox,
monkeypox, and rabies are examples of other diseases that have
also crossed species to humans.) The rapid spread of both diseases
throughout the world came about, at least partially, as a result
of changes in global transportation patterns. Both diseases are
viral in origin. Both diseases are felt, with good reason, to
be the most serious plague of their epoch. Both diseases cause
severe morbidity. Both diseases have serious lifelong consequences.
Both diseases have a high mortality rate. Both diseases lead to
severe social stigma. Persons suffering from both diseases are
(or were) socially shunned. Neither disease is curable, given
the contemporary state of medical science. And in the case of
both diseases, experiments were (or are being) proposed which
try to protect people against contracting the disease by means
of inoculating them with the exact same agent that seems to cause
the disease.
Taking note of these intriguing similarities between smallpox
and AIDS, despite all the differences between them, may prove
to be instructive. It may also provide something of an antidote
to the threatening sense of dejection, almost bordering on hopelessness,
that sometimes challenges those who hope to someday find a vaccine
against this terrible disease. Smallpox, after all, is the one
disease that the human race has completely eradicated.
Jenner
homepage and Table of Contents
preface | Introduction | chp
1 | chp
2 | chp
3 | chp
4
cchp 5 | chp
6 | chp
7 | chp 8 |
App I | App
II
Ethical
Issues in HIV Vaccine Trials
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