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Is the message getting through? We already know enough about AIDS to prevent
its spread, but ignorance, complacency, fear and bigotry continue to stop many
from taking adequate precautions.
We know enough about how the infection is transmitted to protect ourselves
from it without resorting to such extremes as mandatory testing, enforced
quarantine or total celibacy. But too few people are heeding the AIDS message.
Perhaps many simply don't like or want to believe what they hear, preferring
to think that AIDS "can't happen to them." Experts repeatedly remind us that
infective agents do not discriminate, but can infect any and everyone. Like
other communicable diseases, AIDS can strike anyone. It is not necessarily
confined to a few high-risk groups. We must all protect ourselves from this
infection and teach our children about it in time to take effective
precautions. Given the right measures, no one need get AIDS.
The pandemic continues:
Many of us have forgotten about the virulence of widespread epidemics, such as
the 1917/18 influenza pandemic which killed over 21 million people, including
50,000 Canadians. Having been lulled into false security by modern antibiotics
and vaccines about our ability to conquer infections, the Western world was
ill prepared to cope with the advent of AIDS in 1981. (Retro- spective studies
now put the first reported U.S. case of AIDS as far back as 1968.) The arrival
of a new and lethal virus caught us off guard. Research suggests that the
agent responsible for AIDS probably dates from the 1950s, with a chance
infection of humans by a modified Simian virus found in African green monkeys.
Whatever its origins, scientists surmise that the disease spread from Africa
to the Caribbean and Europe, then to the U.S. Current estimates are that 1.5
to 2 million Americans are now probably HIV carriers, with higher numbers in
Central Africa and parts of the Caribbean.
Recapping AIDS - the facts:
AIDS is an insidious, often fatal but less contagious disease than measles,
chicken pox or hepatitis B. AIDS is thought to be caused primarily by a virus
that invades white blood cells (lymphocytes) - especially T4-lymphocytes or
T-helper cells - and certain other body cells, including the brain. In 1983
and 1984, French and U.S. researchers independently identified the virus
believed to cause AIDS as an unusual type of slow-acting retrovirus now called
"human immunodeficiency virus" or HIV. Like other viruses, HIV is basically a
tiny package of genes. But being a retrovirus, it has the rare capacity to
copy and insert its genes right into a human cell's own chromo- somes (DNA).
Once inside a human host cell the retrovirus uses its own enzyme, reverse
transcriptase, to copy its genetic code into a DNA molecule which is then
incorporated into the host's DNA. The virus becomes an integral part of the
person's body, and is subject to control mechanisms by which it can be
switched "on" or "off". But the viral DNA may sit hidden and inactive within
human cells for years, until some trigger stimulates it to replicate. Thus HIV
may not produce illness until its genes are "turned on" five, ten, fifteen or
perhaps more years after the initial infection.
During the latent period, HIV carriers who harbour the virus without any sign
of illness can unknowingly infect others. On average, the dormant virus seems
to be triggered into action three to six years after first invading human
cells. When switched on, viral replication may speed along, producing new
viruses that destroy fresh lymphocytes. As viral replication spreads, the
lymphocyte destruction virtually sabotages the entire immune system. In
essence, HIV viruses do not kill people, they merely render the immune system
defenceless against other "opportunistic: infections, e.g. yeast invasions,
toxoplasmosis, cytomegalovirus and Epstein Barr infections, massive herpes
infections, special forms of pneumonia (Pneumocystis carinii - the killer in
half of all AIDS patients), and otherwise rare malignant tumours (such as
Kaposi's sarcoma.)
Cofactors may play a crucial contributory role:
What prompts the dormant viral genes suddenly to burst into action and start
destroying the immune system is one os the central unsolved challenges about
AIDS. Some scientists speculate that HIV replication may be set off by
cofactors or transactivators that stimulate or disturb the immune system. Such
triggers may be genetically determined proteins in someone's system, or
foreign substances from other infecting organisms - such as syphilis,
chlamydia, gonorrhea, HTLV-1 (leukemia), herpes, or CMV (cytomegalovirus) -
which somehow awaken the HIV virus. The assumption is that once HIV
replication gets going, the lymphocyte destruction cripples the entire immune
system. Recent British research suggest that some people may have a serum
protein that helps them resist HIV while others may have one that makes them
genetically more prone to it by facilitating viral penetration of T-helper
cells. Perhaps, says one expert, everybody exposed to HIV can become infected,
but whether or not the infection progresses to illness depends on multiple
immunogenic factors. Some may be lucky enough to have genes that protect them
form AIDS!
Variable period until those infected develop antibodies:
While HIV hides within human cells, the body may produce antibodies, but, for
reasons not fully understood, they don't neutralise all the viruses. The
presence of HIV antibodies thus does not confer immunity to AIDS, nor prevent
HIV transmission. Carriers may be able to infect others. The usual time taken
to test positive for HIV antibodies after exposure averages from four to six
weeks but can take over a year. Most experts agree that within six months all
but 10 per cent of HIV-infected people "seroconvert" and have detectable
antibodies.
While HIV antibody tests can indicate infection, they are not foolproof. The
ELISA is a good screening test that gives a few "false positives" and more
"false negatives" indicating that someone who is infected has not yet
developed identifiable antibodies.) The more specific Western Blot test, done
to confirm a positive ELISA, is very accurate. However, absence of antibodies
doesn't guarantee freedom form HIV, as someone may be in the "window period"
when, although already infected, they do not yet have measurable levels of HIV
antibodies. A seropositive result does not mean someone has AIDS; it means
(s)he is carrying antibodies, may be infectious and may develop AIDS at some
future time. As to how long seropositive persons remain infectious, the June
1987 Third International Conference on AIDS was told to assume "FOR LIFE".
What awaits HIV-carriers who test positive?:
On this issue of when those who test HIV positive will get AIDS, experts think
that the fast track to AIDS is about two years after HIV infection; the slow
route may be 10, 15, or more years until symptoms appear. Most specialists
agree that it takes at least two years to show AIDS symptoms after HIV
infection, and that within ten years as many as 75 per cent of those infected
may develop AIDS. A report from Atlanta's CDC based on an analysis of blood
collected in San Francisco from 1978 to 1986, showed a steady increase with
time in the rate of AIDS development among HIV-infected persons - 4 percent
within three years; 14 percent after five years; 36 percent after seven years.
The realistic, albeit doomsday view is that 100 percent of those who test
HIV-positive may eventually develop AIDS.
Still spread primarily by sexual contact:
AIDS is still predominantly a sexually transmitted disease: The other main
route of HIV infection is via contaminated blood and shared IV needles. Since
the concentration of virus is highest in semen and blood, the most common
transmission route is from man to man via anal intercourse, or man to woman
via vaginal intercourse. Female HIV carriers can infect male sex partners.
Small amounts of HIV have been isolated from urine, tears, saliva, cereb-
rospinal and amniotic fluid and (some claim) breast milk. But current evidence
implicates only semen, blood, vaginal secretions and possibly breast milk in
transmission. Pregnant mothers can pass the infection to their babies. While
breastfeeding is a rare and unproven transmission route, health officials
suggest that seropositive mothers bottle feed their offspring.
AIDS is not confined to male homosexuals and the high risk groups: There are
now reports of heterosexual transmission - form IV drug users, hemo- philiacs
or those infected by blood transfusion to sexual partners. There are a few
reported cases of AIDS heterosexually acquired from a single sexual encounter
with a new, unknown mate. And there are three recent reports of
female-to-female (lesbian) transmissions.
Spread of AIDS among drug users alarming:
In many cities, e.g. New York and Edinburgh, where IV drug use is wide-
spread, IV drug users often share blood-contaminated needles. In New York,
more than 53 percent of drug users are HIV-infected and may transmit the
infection to the heterosexual population by sexual contact and transmission
from mother to child. Studies in Edinburgh, where 51 percent of drug users are
HIV-infected, show that providing clean needles isn't enough to stem
infection. Even given free disposable needles, many drug abusers preferred the
camaraderie of shared equipment. Only with added teaching programs and free
condom offers, are educational efforts likely to pay off. In New Jersey,
offering free treatment coupons plus AIDS education brought 86 percent of
local drug users to classes. A San Francisco program issued pocket-size
containers of chlorine bleach to IVDAs with instructions on how to kill HIV
viruses. The Toronto Addiction Research Foundation notes a similar demand for
AIDS information.
Risk of infection via blood transfusion very slight:
Infection by blood transfusion is very rare in Canada today. As of November
1985, the Red Cross, which supplies all blood and blood products to Canadian
hospitals, had routinely tested all blood donations for the HIV antibody. In
1986, when we last discussed AIDS, the Red Cross reported the incidence of
HIV-positive blood samples as 25 in 100,000. Now, at the start of 1988, only
10 per 100,000 blood samples are found to be infected - which, of course, are
discarded. Only a tiny fraction of HIV-positive blood (from HIV-infected
people who haven't yet developed detectable antibodies) can now slip through
the Red Cross screening procedure. The minimal risk is further decreased by
screening methods, medical history-taking, questionnaires and donor inter-
views. Very few people at risk of AIDS now come to give blood. The "self-
elimination form", filled out in a private booth, allows any who feel
compelled by peer pressure to donate blood, total privacy to check the box
that says "Do not use my blood for transfusion."
As to banking one's own blood, or autologous donations, the Red Cross permits
a few "medically suitable" people, referred by their physician, to store their
blood if they are likely to need blood transfusion in upcoming elective
surgery. They can bank up to four units of blood, taken in the five weeks
before surgery.
Finally - it can be categorically stated - IT IS ABSOLUTELY IMPOSSIBLE TO GET
AIDS BY GIVING BLOOD!!!
Minimal risk to health care workers:
While health care personnel face a slight risk of HIV infection, all cases
reported to date have been due to potentially avoidable mishaps or failure to
follow recommended precautions. Of thousands caring for AIDS patients
worldwide, only a tiny percentage has become infected, and so far no Canadian
health personnel have become HIV-infected. A survey done by the Federal Centre
for AIDS (FCA) of 50 workers occupationally exposed to AIDS showed that none
became infected. A british hospital study on staff looking after 400 AIDS
patients over several years found none who became HIV-positive. In one U.S.
survey, 7 out of 2,500 health care workers seroconverted and developed HIV
antibodies all by potentially avoidable accidents such as needle pricks,
exposure to large amounts of blood, body fluids spattered into unprotected
mouth, eyes or open sores. The reported mishaps underscore the need for
rigorous, vigilant compliance with preventive guidelines.
Universal body substance precautions (BSP) urged:
The newest guidelines suggest that every health care worker, including
dentists, should handle all blood and body fluids as if infectious. Testing
all patients for HIV is not practical and does not confer protection. Rely-
ing on tests that are not 100 per cent accurate would only induce a false
sense of security. Rather than trying to identify infected persons, the CDC
and Ottawa's FCA now promote a philosophy that regards all patients as
potentially infected. (At Johns Hopkins in Baltimore, about six percent of
admissions to the Traumatic Emergency Unit recently tested HIV-positive.)
Hospital and health care workers (including those caring for patients at home)
are encouraged to "think AIDS" and protect themselves. All patients should be
handled in a way that minimizes exposure to blood and body fluids, e.g. by
always wearing gloves when touching open sores, mucous membranes, taking
blood, attending emergencies, putting in IV needles, touching blood- soiled
items, with scrupulous hand-washing between patients (and whenever gloves are
removed), wearing masks, eye protection, plastic aprons and gowns when
appropriate. Taking such precautions will not only protect against AIDS but
also against more infectious agents such as hepatitis B and some hospital
acquired infections. We are all being forced to remember stringent anti-
infection rules!
Absolutely no evidence of spread by casual contact:
All the research to date points to the fact that AIDS is not very easy to
catch. One University of Toronto microbiologist speculates that those with
high antibody counts are probably not very infectious. The most infectious
appear to be seemingly healthy persons carrying HIV without any sign of
disease as yet.
AIDS CANNOT BE PICKED UP CASUALLY via doorknobs, public washrooms, shared
school books, communion coups, cutlery or even by food handlers with open
cuts. A relatively weak virus, HIV is easily killed by a dilute 1 in 10
solution of Javex/bleach, rubbing alcohol and other disinfectants. Even where
parents or caregivers have cleaned up HIV-infected blood, vomit or feces, HIV
has not been transmitted. It is perfectly safe to share a kitchen, bathroom,
schoolroom or workbench with HIV-infected individuals. But it is inadvisable
to share toothbrushes, razors, acupuncture needles, enema equip- ment or sharp
gadgets, which could carry infected blood through the skin.
ORDINARY, NONSEXUAL WORKPLACE AND CHILDHOOD ACTIVITIES DON'T TRANSMIT AIDS.
The rare exception might be direct blood-to-blood contact via cuts or wounds
if infected blood (in considerable amounts) spills onto an open sore. Even in
such cases a swab with dilute bleach can kill HIV viruses.
Not spread by mosquitoes and other insects:
There's no evidence of HIV transmission by insects. Researchers report that
the AIDS virus cannot multiply or survive inside a mosquito. The infection
pattern in Africa - where children who are not sexually active might be
expected to have AIDS if mosquito bites were a real threat - shows no sign of
insect transmission.
Vaccines still a way off:
Scientists caution that a safe, effective vaccine against HIV may be at least
a decade away, mainly because, like the influenza virus, HIV mutates (changes
structure) quickly, producing different strains. (Several different HIV
strains have already been isolated.) An ideal vaccine must be able to
stimulate neutralization of both "free" viruses and those hidden within
lymphocytes, such as T-helper cells.
Science Essays
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