email Dr Kerns
Furthermore, urges the Thesis position,
the uniqueness of this disease makes it an especially formidable
enemy, and one that will be particularly difficult to get under
any semblance of control.
This is the case because the more we learn about this disease,
the more we are learning that "whatever else AIDS is, it
is not just another disease," says Dr June Osborn, past chair
of the US National Commission on AIDS. Nor is AIDS just another
epidemic, nor even just another global pandemic. Several features
of this disease make it unique among diseases, and unique among
epidemics.
2.1 High morbidity
and mortality
We are dealing with a disease
that has an exceptionally high degree of morbidity and mortality.
It has been conservatively estimated that 90 per cent, perhaps
more, of those who become infected with HIV will eventually contract
AIDS and die of it. This conservative estimate is considered quite
significant; very few microbes kill as many as 50 per cent of
those they infect.
2.2 Lifelong
infectiousness
We are dealing with a disease
that is life long. This means that HIV positive persons will be
infectious for the rest of their lives. Not only is this an enormous
burden of personal tragedy for them as individuals, but it also
means that any behavioral changes required of them will need to
be put into effect for the rest of their lives.
2.3 Lengthy asymptomatic
stage
We are dealing with a disease
that has an extremely long asymptomatic period - some call it
a "latency" period - during which time the infected
person shows no visible signs of infection, but is fully capable
of passing the virus to anyone with whom blood or body fluids
are shared. Of even more concern to some is the fact that during
the first several weeks immediately following the new infection,
none of the commonly used tests for detecting HIV infection will
be able to detect that there has been a new infection. Therefore,
newly infected persons do not have any way of detecting whether
or not they have become infected with HIV, and consequently, neither
do their sexual partners have any way of knowing whether their
partner has been infected. And now recent evidence suggests that
during those first 4 - 6 weeks immediately following a new infection,
the newly infected person is especially contagious to others.
In other words, "people are extremely contagious in the first
60 days after getting [HIV] - the same period in which they don't
[yet] know they have it".
Furthermore, except for getting tested, there are no obvious signs
of infection visible for years, perhaps up to ten or more years.
There is no visible evidence at all that a person might be infected
with HIV. This means that infected persons themselves may have
no idea that they are infected, and certainly no one looking at
them would have any reason to think they are infected.
One of the many consequences of this reality is that the success
of any prevention measures we take now will not be evident for
many years to come. This poses a serious public health problem
because when there is such a long period of time between cause
and effect (between HIV infection and AIDS), it is difficult for
people to see any real connection between their behavior now and
the possible consequences many years later. This makes it difficult
to motivate people (or governments) to take preventive precautions.
2.4 Highly mutable
We are dealing with a virus
which is highly mutable, which replicates rapidly and mutates
often. This means that researchers and clinicians are aiming at
a constantly moving target, a target that changes its coat almost
every time it reproduces. (More on this in chapter 5 below.)
2.5 Effective
modes of transmission
We are dealing with a virus
that, by chance, has figured out some very effective ways of getting
itself transmitted from one host to another. It is true that HIV
is not transmitted by casual contact, (which is very good news)
but some of the ways that it is transmitted - sexual contact,
blood transfusion, birth, and so on - are fairly common behaviors.
Many people have sexual contact with others, have blood transfusions,
and all of us have been born. These are not unusual or abnormal
behaviors. Of those who have so far been infected with HIV in
the world, over 85 per cent have been infected via sexual contact.
When we add injection drug use to our list of modes of transmission,
we see that between drug use and sexual activity, HIV gets itself
transmitted from host to host by means of some of the most "biologically
urgent" of human behaviors. They are also behaviors that
are largely private, often pleasurable, and occasionally unlawful,
which means that they are behaviors that are liable to be rather
difficult to exert any social controls over. If a parasite (such
as HIV) has to find some effective way to get from one host to
another in order to insure its continued propagation, HIV has
certainly found some very effective ways to do that.
2.6 Destroys
the immune system
We are dealing with a disease
which, unlike almost any other, targets the immune system itself,
and destroys the very system whose purpose it is to protect us
from disease. Furthermore, HIV targets and kills one of the key
cells in the immune system, the T4 cell (or CD4 cell), which orders
and orchestrates the whole cellular and humoral immune response.
When these T4 cells are destroyed, the immune system itself is
destroyed.
2.7 Viral reservoir
expanding
As the epidemic continues
to grow in numbers and extent, that is, as the total number of
infected persons grows daily, the total quantity of HIV on the
planet is also growing daily. This means that "the reservoir
of infection, that is, the total sum of people infected who can
also act as a source of infectious virus to others, is also constantly
and progressively expanding". This has the total overall
effect of amplifying the spread of infection. The faster it spreads,
the faster it spreads.
These seven features of the disease make it a particularly formidable opponent. Dr Barry D Schoub, Director of the National Institute of Virology at the University of Witwatersrand in Johannesburg, sums up the matter thus:
[T]he ability of the virus to cause a slow, progressive and permanent infection with permanent infectivity makes it a unique cause of epidemic disease. Thus, with no recovery, no loss of infectivity, no development of either individual or herd immunity, there is no known biological mechanism which can stop the continuing expansion of the disease unless an effective vaccine were to come about, and at present there is no feasible design for such an effective vaccine. The progressive increase in the pool of HIV can, in theory, only lead to an exponential increase in the number of individuals who will become infected until eventually the majority of the sexually active population will be infected unless interventions are at lease moderately successful.
Given a disease with these particular characteristics, it is small wonder that this epidemic is growing at the rate it is. All (all!) reliable evidence indicates that, for as far into the future as we can presently reliably estimate, the pandemic will probably continue to grow at its present, or even perhaps at an accelerating, rate.