HLTH101 Lecture 2: Pisani Instant Expert HIV
15 Dec 2016
School
Department
Course
Professor
HIV
Elizabeth Pisani
INSTA NT
EXPERT
15
110903_F_IE_Aids.indd 25 23/8/11 14:04:28
ii | NewScientist
PREHISTORY
immune system becomes
progressively more damaged and
the number of CD4 cells falls. Other
infections set in that a healthy
immune system would beat easily,
such as Pneumocystis carinii
pneumonia. These are the
opportunistic infections that make
up the syndrome known as AIDS,
and this is what kills people.
When first infected, most people
feel mild flu-like symptoms at worst,
then nothing for the nine or 10 years
during which HIV typically lies latent
within their immune cells.
That means people often live with
the infection, and, crucially, are able
to pass it on, for many years without
knowing it.
NIBSC/SCIENCE PHOTO LIBRARY
SVEN TORFINN/PANOS
Some time during
HIV crosses from
chimpanzees
to humans
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HIV has spread so far partly because it is so good at its
job. Like a computer virus that starts by knocking out
anti-viral software, HIV targets the immune cells at
the front line of our body’s defences. It locks onto CD4
immune cells, which usually protect us against viruses
and other microbes, and inserts itself into their DNA.
When HIV first enters the body it replicates fast,
causing a spike in the amount of virus present in the
blood and genital fluids, known as the “viral load”.
Because we recognise the virus as foreign, we begin
to make antibodies. These bring down the viral load,
but crucially never manage to eradicate the virus,
in part because some sit quietly in the DNA of
apparently healthy CD4 cells, beyond the reach
of the immune system.
Over time, as the body confronts other infections,
those apparently healthy cells get called up. That
stirs HIV into action; the cell spews out more virus
and dies. As the viral load continues to rise, the
A VIRUS FIT FOR PURPOSE
The exact origins of HIV are hotly debated, but
genetic sequencing techniques are shedding
some light on how the virus reached critical mass
and began spreading around the world.
HIV-1, the most common type, is descended
from a virus still found in chimpanzees living in
central Africa. The earliest virus found so far was
in a lymph node taken from a man in 1959 in what
was then Belgian Congo. Comparing that with
other early samples shows that the virus must
have crossed over from chimpanzees and started
to circulate and diverge in humans by the first
decade of the 20th century.
HIV probably crossed the species barrier in the
bloody process of butchering chimps for food.
The spread of the virus in the Belgian and French
colonies of central Africa in the mid-20th century
was probably accelerated by rapid, male-
dominated urbanisation and the concentration of
labourers in camps with attendant prostitution.
Health campaigns where needles were
repeatedly reused may also have contributed.
The links between Francophone central Africa
and Haiti provided HIV with a staging post to the
western hemisphere; genetic analysis suggests
that the virus was imported from Haiti to the US
in the late 1960s.
The sexual liberation of the 1960s and 1970s
combined with homophobia concentrated large
groups of sexually active gay men in small
enclaves of tolerance in cities like New York and
San Francisco. Anal sex is inherently more
dangerous for passing on viruses than vaginal
sex because it is more likely to cause small tears
and lesions. That, together with a high turnover
of partners, provided perfect conditions for the
rapid spread of HIV. Because these men were
young, otherwise healthy and largely well
educated and white, their illness attracted
attention in a way that earlier cases in Africa
and the Caribbean had not. AIDS came out
of the shadows.
NewScientist | iii
AIDS was without doubt the dening epidemic of the late 20th
century. Though the virus behind it was only identied in the
mid-1980s, by the end of the century HIV had insinuated itself into
over 36 million adults. AIDS ushered in an era of patient activism and
brought money, health and politics together in ways that have
changed the face of global health.
ORIGINS
A NEW DISEASE
When AIDS first
emerged, a diagnosis
was a death sentence
On 5 June 1981, a brief report, of
monumental import, was published
by the US public health agency, the
Centers for Disease Control and
Prevention in Atlanta, Georgia. Five
gay men in Los Angeles had come
down with an unusual form of
pneumonia, caused by the bacterium
Pneumocystis carinii, which wouldn’t
normally affect healthy young
adults. The CDC paper described a
malfunction of the immune system
that was in some way acquired
sexually; it prompted a wave of similar
reports from San Francisco, New York
and elsewhere.
So many of the cases were in gay
men that the condition was first
termed GRID, for gay-related immune
deficiency. But it quickly emerged that
other groups of people were affected
too – haemophiliacs, drug injectors,
women who had had sex with affected
men, their newborns and, at the
time bafflingly, Haitians. In 1983
the CDC concluded that the condition,
by then renamed acquired immune
deficiency syndrome, or AIDS, was
probably passed on by sex and
exposure to blood.
By then cases of AIDS had turned
up in 15 countries, largely among
people in the groups already
identified. But in France and Belgium
immigrants from central Africa also
had a condition that looked very much
like AIDS. Like the Haitians in the US,
these men and women were not
linked with the behaviours thought
to spread AIDS.
The measured tones of the CDC’s
reports contrasted with a hysterical
public reaction. Conservative
moralists proclaimed AIDS the wages
of sin, the San Francisco police force
issued gloves to cops who might come
into contact with people with AIDS,
and the press became ever more shrill.
Meanwhile US president Ronald
Regan did not say the word “AIDS”
until 1985 – by then more than
12,000 Americans had died.
People panicked, in part because
they didn’t know what caused the
illness. Though French scientists
discovered a virus they thought
responsible for AIDS in 1983, it
wasn’t until US scientists identified
the same virus a year later that the
cause of AIDS was agreed to be
found. In 1986 it was named human
immunodeficiency virus, or HIV.
With the virus identified and
screening of blood donations possible,
the early hysteria began to fade.
But the world’s response to HIV is,
to this day, shaped by its emergence
in the bathhouses and gay bars
of the US.
JEFFREY MARKOWITZ/SYGMA/CORBIS
