AIDS: Science at a Crossroads

being felt a decade later. In neighbouring Glasgow, the rate of infection among drug users is
dramatically lower. The importance of unforeseen local factors in all these mini-epidemics
demonstrates the dangers of becoming complacent about the spread of HIV and the patterns of
infection around the world.
STDs: a major factor of risk
Even given the complexity of the different mini-epidemics, it is difficult at first to understand why the
broad patterns of infection in the industrialised world and the developing countries appear to be so
different. Why do so many more heterosexuals have HIV in Africa, Asia, Latin America and the
Caribbean than in North America, Australasia and Europe?
One answer is that in developing countries, rates of infection with other sexually transmitted diseases
(STDs) such as gonorrhoea, chlamydia, syphilis and chancroid are much higher than in the
industrialised countries, and many of these STDs help to fuel HIV's spread. According to a WHO
estimate in 1990, there are some 250 million new cases of STDs worldwide every year and, whereas
STDs have largely declined in the industrialised world since the 1970s, in developing countries they
are among the leading causes. of disease burden (1). Estimates of the prevalence of gonorrhoea in
pregnant women in developing countries range from 3 to 15%.
Numerous studies have found that STDs help the spread of HIV, partly by increasing inflammation and
bleeding in the genital areas and therefore increasing the numbers of cells that can harbour HIV. The
effect is to enhance dramatically the efficiency with which HIV spreads from one sexual partner to
another. In a population where the rate of partner change is very low and where other STDs are rare,
the chance of becoming infected with HIV by a single sex act may be - very roughly - as low as 1
per 1,000. But in groups where the prevalence of STDs is high, such as commercial sex workers, the
chance of becoming infected appears to be much higher (2).
Women, once again, are at greatest risk. With most genital infections, it is much easier for a man to
infect a woman than for a woman to infect a man. In communities where medical care is difficult to
obtain, STDs go neglected, often for months or years. Most STDs are simply and cheaply treated once
they have been diagnosed, but women in particular may have no symptoms.
A second answer to the question of why the developing world is so disproportionately affected is that
women's social and economic dependence on men makes them particularly vulnerable. Many women
are in unequal sexual relationships where they cannot protect themselves. In many communities, they
are not expected to discuss sex with men, still less demand safer sex. Women who have no income and
no rights to property cannot leave men who may coerce them into sex, and may be forced into
commercial sex work to support themselves. Young women are at the greatest risk of all. More than
half of all infections in women happen before the age of 24, according to WHO.
4. DESPERATELY SEEKING ANSWERS: HIV'S MYTHS AND
MYSTERIES
More than virtually any other disease, AIDS has generated myths and far-fetched theories about its
origin, its causes and even its very existence. These are probably linked to fear and denial prompted by
a virus which is fatal, infectious, incurable and sexually transmitted - and can infect people for years
before they show any signs of illness.
Where did HIV come from (and where is it going)?
HIV is not - despite persistent beliefs - an alien from outer space or an agent of biological warfare.
It has close relatives in the animal kingdom. Immunodeficiency viruses are known to infect cats, cattle,

and monkeys, for example. The closest relatives of HIV are found in monkeys, and many scientists
believe that at some point in recent history, immunodeficiency viruses entered the human population
from other primates.

Panos Briefing: AIDS: SCIENCE AT A CROSSROADS 6