confronting a killer:
HIV/AIDS epidemic: a brief overview
A new disease emerges
AIDS was first
described in 1981, when previously healthy young adults -- mainly men
living in urban areas of the United States -- began falling ill with
opportunistic infections previously unknown among this age group.
Similar infections were soon described in Africa, the Caribbean and
Europe; AIDS was clearly an epidemic disease. Most of these young people
died, and a host of discrepant hypotheses emerged, but a bloodborne
viral pathogen was suspected early on. In 1983, this suspicion was
confirmed when Professor Luc Montagnier and others discovered a novel
pathogen: a retrovirus tropic for the CD4 cells that orchestrate
cell-mediated immunity and protect humans from a broad range of viral,
mycobacterial, and fungal pathogens.
screening was available, transfusion-associated transmission was
eliminated, but HIV was not easily stopped. Condoms were shown to be
effective in preventing sexual transmission of HIV, but it was not long
before those who studied AIDS concluded that male condoms alone would
not be enough in settings in which poverty and gender inequality
rendered poor women especially vulnerable to HIV infection (2).
Women in turn transmitted HIV to their unborn children or to
breastfeeding infants. Injecting drug use introduced HIV to previously
untouched regions of the former Soviet Union and to parts of Asia.
Poor-quality health care -- including the reuse of syringes, needles,
and other medical paraphernalia -- also contributed to the entrenchment
of this new epidemic.
How well has the
international community coped with this new threat to global health? In
spite of remarkable scientific achievements -- the development of
inexpensive diagnostics by the mid-1980s, the sequencing of the entire
HIV genome less than 15 years later, and the development of effective
antiretroviral therapy by 1995 -- the virus has continued to spread (see
Figure 3.2). It is estimated that during the course of 2002 some 5
million people became infected with HIV, and almost 3 million people
died of AIDS.
Everywhere in the
world, HIV is transmitted through a fairly limited number of mechanisms.
HIV is a bloodborne retrovirus and is transmitted through sexual
contact, contaminated blood transfusions, injecting drug use, failure to
observe what are now termed in medical circles "universal precautions",
and from mother to infant during pregnancy, delivery and breastfeeding.
The most heavily
burdened continent is Africa, where the spread of the pandemic has been
accelerated by a variety of factors, including widespread poverty,
gender inequality, and health systems weakened by pressures such as the
large external debt loads of states. Africa is home to more than 70% of
those currently infected with HIV. Of all AIDS deaths worldwide -- 28
million at the end of 2002 -- the majority have also occurred on this
continent (3). HIV infection has fanned epidemics of TB in some
African countries, increasing the risks to the whole population,
regardless of serostatus. Across sub-Saharan Africa, rates of TB have
more than trebled, and many conclude that the disease cannot be
controlled without aggressive treatment of AIDS (4).
Debates about the
relative importance of different modes of HIV transmission in
sub-Saharan Africa persist, but the evidence indicates that HIV in this
region is primarily a sexually transmitted pathogen (5).
Nonetheless, the difficulties involved in following universal
precautions in overburdened and under-resourced health care facilities
may lie at the root of many AIDS deaths in Africa (6). In many
regions, unsafe blood transfusions continue, underscoring the importance
of blood safety as a component of effective HIV/AIDS control.
The immensity and
rapidity of the spread of HIV have reversed gains in life expectancy in
many African countries (see Chapter 1). But the worst may be yet to
come. The poorer regions of Asia, including densely populated southern
Asia, are the latest areas to be affected by the emerging AIDS epidemic.
There has been an alarming rise in HIV/AIDS cases in Asia over the past
two decades; the burden of disease and death in the region will be
enormous if current epidemiological trends are not slowed or reversed.
countries are also afflicted. The Russian Federation and Ukraine, along
with other countries in eastern Europe and countries in central Asia,
have the most rapidly expanding HIV epidemics. Here the disease is more
closely tied to injecting drug use, which itself is linked to a rapid
rise in indices of social inequality (3). Although the absolute
number of AIDS cases in the former Soviet Union remains relatively
small, the epidemic is expanding rapidly in the Russian Federation and
other countries in the region (see Box 3.1). Prison-seated epidemics of
TB, including drug-resistant strains, will be further fanned by the
rapid rise in HIV incidence already documented among Russian prisoners.
Only aggressive harm-reduction efforts and improved therapy for TB can
stem what is a peculiarly modern epidemic of two linked diseases that
are now colliding within countries reaching from western Europe to the
Pacific Ocean (7).
3.1 HIV/AIDS in the European Region
The European Region
is experiencing the fastest growing HIV epidemic in the world, and
significant further growth is likely. Between 1995 and 2003, the number
of newly reported HIV infections in western Europe doubled to almost 170
000, and in central and eastern Europe grew from 27 000 to 320 000. It
is now estimated that at least 1.7 million people in Europe are already
infected with HIV.
An epidemic of
injecting drug use is fuelling the HIV epidemic. In the former Soviet
Union, where two-thirds of all Europeans infected with HIV live, 84% of
all HIV cases with a known transmission route are attributable to
injecting drug use. In western Europe, sexual transmission is the
dominant route, with the largest number of infections among men who have
sex with men and among immigrant populations from high prevalence
epidemic has changed dramatically since its onset in the 1980s.
Sustainable, long-term, comprehensive and massive response in western
Europe, with extensive funding and political support for prevention,
treatment and care limited the spread of the epidemic. Widespread
prevention measures contributed to stabilizing and decreasing
transmission rates, while antiretroviral treatment was also made widely
available. In spite of such measures, the HIV/AIDS epidemic remains a
serious and ongoing challenge in western Europe. In eastern Europe,
limited political commitment and funding, low coverage by prevention
services, severely limited access to treatment and care and high levels
of stigmatization of groups at risk are the main reasons for a
continuously worsening HIV epidemic.
true toll of HIV/AIDS
of HIV, including the dynamics of risk, is instructive. But epidemiology
tells only part of the story. A disease that has so adversely affected
life expectancy will also take a great toll on the social fabric of
heavily burdened societies, above and beyond its terrible cost in
immediate human suffering. To take two examples, AIDS has orphaned an
estimated 14 million African children and will decimate the corps of
teachers, health care workers and civil servants in the hardest-hit
disruptions are manifest in direct economic effects. A recent World Bank
study predicts that South Africa will face "complete economic collapse …
within three generations" if the country does not take effective
measures to combat AIDS (9). But there is much more to the story
than can be measured by economists. Other social scientists are
broadening the analysis to look at the impact of the disease on an array
of events and processes. What, for example, are the social consequences
of having millions of AIDS orphans? How does the disappearance of so
many parents contribute to the spread of armed conflict and the social
pathologies that accompany urban migration and attendant unemployment?
What is the cost of the "burnout" registered among health professionals
across Africa and in other settings where AIDS therapy is not available
to those who need it most (10)? Science is only beginning to
understand the social and economic toll of HIV/AIDS, which is heaviest
in precisely those settings least prepared for a new threat to health