At A Glance
*All figs are for 2013. Source: UNAIDS 2014
Total number living with HIV 35 million
New infections 2.1 million
New infections in children 240,000
AIDS-related deaths 1.5 million
Number receiving treatment 12.9 million
*All figs are for 2013. Source: UNAIDS 2014
Total number living with HIV 24.7 million
New infections 1.5 million
AIDS-related deaths 1.1 million
ASIA & THE PACIFIC
Total number living with HIV 4.8 million
New infections 350,000
AIDS-related deaths 250,000
Total number living with HIV 250,000
New infections 12,000
AIDS-related deaths 11,000
E. EUROPE & C. ASIA
Total number living with HIV 1.1 million
New infections 110,000
AIDS-related deaths 53,000
Total number living with HIV 1.6 million
New infections 94,000
AIDS-related deaths 47,000
MIDDLE EAST & N. AFRICA
Total number living with HIV 230,000
New infections 25,000
AIDS-related deaths 15,000
W. & C. EUROPE & N. AMERICA
Total number living with HIV 2.3 million
New infections 88,000
AIDS-related deaths 27,000
The AIDS pandemic has devastated communities and economies in many of the poorest countries of the world. In 2013, an estimated 1.5 million people died of AIDS and 2.1 million were newly infected with the HIV virus, according to a report by the U.N. programme on HIV/AIDS (UNAIDS).
Overall, 35 million people worldwide are living with the virus, but just over half of them don't realise they have the disease, says UNAIDS.
It's not just the scale of the pandemic that is so devastating –it's also the fact that the majority of those living and dying with the virus are adults in their prime. Southern Africa is the worst-affected region.
Women have been increasingly at risk of infection in poorer countries – mainly due to inequality, social pressures and lack of education about the virus.
Encouragingly, some of the worst-hit regions in the world – sub-Saharan Africa and the Caribbean – have seen a dramatic fall in the number of new infections since 2005.
Overall, the epidemic seems to have fallen in all regions except eastern Europe, central Asia, Middle East and north Africa where the number of new infections is rising.
The factors driving the epidemic vary from region to region. In sub-Saharan Africa, the virus is mainly spread by unprotected heterosexual sex. In some other regions, those most at risk are injecting drug users, sex workers and men who have sex with men.
Billions of dollars have been poured into treatment and prevention programmes and into developing new drugs and vaccines. The proportion of people with access to treatment has soared, but even so only 38 percent of those who need antiretroviral drugs receive them. UNAIDS says billions more dollars are needed in the fight against AIDS.
Exact figures for the numbers of people infected with HIV/AIDS are difficult to calculate. In its 2007 report, UNAIDS significantly revised its figures downwards partly because of improved methodologies for collecting data, as well as a drop in the number of new infections. The revised methodologies lowered the UNAIDS figures for India from 5.7 million cases in 2006 to 2.47 million in 2007, for example.
Economic and social impact
Because the virus affects people aged 15 to 49 the most, it has had a devastating effect on all aspects of life in the worst-hit countries.
Families have lost their breadwinners, and in rural areas agriculture has been severely impacted. More and more grandmothers have had to look after their sick children and then orphaned grandchildren.
The virus also stretches medical services. Resources have to be diverted to treat the disease, and doctors and nurses themselves become infected.
National economies suffer as the workforce and crop production are diminished.
The prevention debate
HIV is transmitted in three ways: through unprotected sex, through blood - particularly through transfusions or intravenous drug use - and from mother to baby via pregnancy, labour or breast milk.
Many governments and agencies use the so-called ABC approach - "Abstain, Be faithful, use a Condom" - to preventing the spread of AIDS. It focuses on sex education programmes on how the virus is spread, encourages abstinence and fidelity, and promotes the use of condoms.
Although sex education and the correct use of condoms have been shown to reduce the spread of the virus, these methods are often controversial in communities where religious leaders prefer to promote abstinence and fidelity.
Many in developing countries have difficulty buying condoms - either because they are unavailable or because they are too expensive. People often depend on free handouts.
The ABC approach has come under fire for not addressing the needs of women.
And the U.S. government was criticised by many for promoting abstinence-only messages and not putting enough emphasis on condom use.
The United States has channelled billions of dollars into the fight against HIV/AIDS since 2003 through its President's Emergency Plan for AIDS Relief (PEPFAR) programme.
In November 2011, U.S. Secretary of State Hillary Clinton said it was setting a new direction for its AIDS campaign, emphasizing HIV drug treatments, new efforts to stop mother-to-child transmission of HIV, and voluntary male circumcision.
Making HIV testing and treatment free for all is an important factor in preventing the spread of HIV. Free treatment encourages people to come forward for testing without fear of receiving a death sentence, and as a result it reduces the social stigma surrounding the disease.
Taking AIDS drugs may dramatically reduce the risk of infection among heterosexual couples, research published in 2011 found.
Treating HIV positive women during pregnancy also helps prevent the spread of the virus to their babies.
Male circumcision reduces the risk of infection in men by 66 percent, UNAIDS says.
Some countries have had significant success in curbing the pandemic. Two examples are Brazil and Cuba, both of which responded quickly to the threat of the virus in the late 1980s and early 1990s.
Brazil had the same prevalence rate as South Africa in the early 1990s. Now, having launched rigorous anti-HIV campaigns, promoted condom use and provided free treatment for all, prevalence there is 0.6 percent or less, compared with South Africa’s 19.1 percent.
Cuba, too, has succeeded in containing the virus, partly by using highly controversial methods of quarantining and enforced education programmes in sanatoria.
Social stigma and discrimination against people living with HIV are among the biggest barriers to dealing with the AIDS pandemic, according to UNAIDS.
They prevent governments from acknowledging and addressing AIDS, and discourage people from getting tested. They also dissuade people who know they carry the virus from sharing their status with others and seeking treatment.
One effective way of overcoming stigma is to make treatment readily available, thereby reducing the fear of AIDS. But many governments cannot afford it.
Another important factor is having a strong movement of people living with HIV who can support each other, provide a voice at local and national levels, and campaign on issues like free treatment.
Other support groups use less orthodox methods. In Zimbabwe, for example, one woman set up a dating agency exclusively for people living with HIV, hoping to counter the belief that people living with the virus should be condemned to celibacy for life.
People in high risk groups – men who have sex with men, sex workers and injecting drug users – experience additional stigma, and many countries do not target these groups in their HIV programmes.
Women and HIV
In many developing countries, inequality, social pressures and lack of education about the virus often make women more vulnerable to HIV infection than men.
In sub-Saharan Africa, women and girls make up 58 percent of the HIV-positive population.
Young women aged between 15 and 24 are particularly vulnerable to HIV. In sub-Saharan Africa, they are twice as likely as young men to have HIV, says UNAIDS.
Being married can increase their vulnerability to HIV. Among 15- to 19-year-old girls who are sexually active, being married increased their chances of having HIV by more than 75 percent, a study in Kenya and Zambia by University of Chicago researchers found.
Many government and agency HIV prevention strategies follow the ABC approach. Although this has prevented large numbers of infections, it fails to address the fact that many women do not have the power to abstain from sex, and cannot rely on their partner's fidelity or insist on condom use, says the Global Coalition on Women and AIDS (GCWA).
WHO says women's right to autonomy on sexual matters "is respected almost nowhere".
Some say female condoms, although more expensive than male ones, could provide a solution. Others are developing microbicide gels which can kill the virus, and could be used by women before intercourse without their partner's knowledge.
Education is also a problem. Many young women do not know how HIV/AIDS is spread or that condom use can prevent HIV transmission.
HIV infection rates can rise during humanitarian crises. Rape is used in many places as a weapon of war. Even where it is not, some women and girls may be forced into sex work as displaced families lose their normal source of income.
Lastly, women who are HIV-positive, or have been widowed by AIDS, often suffer discrimination, abandonment and violence, says the GCWA. In some countries, they lose their homes, inheritance, livelihoods and even their children when their husbands die.
Worldwide, the number of children newly infected with HIV is falling. In 2013, the figure was 240,000 - 40 percent lower than in 2009, according to UNAIDS.
Modern improvements in health screening can reduce the risk of transmission from mother to child, as can a course of antiretroviral drugs during pregnancy.
But many children become infected in this way every year because many pregnant women in developing countries do not have access to proper health care, HIV-testing facilities or education about the virus.
Without treatment, about half of children infected with HIV die before their second birthday, the U.N. Children's Fund says. But children are much less likely to receive treatment than adults.
Only a few drugs can be safely used on children, who need different doses and different forms to adults. Syrups are more suitable for children but more expensive to produce and have a shorter shelf life.
Drug companies have not focused on making medicines for children, partly because the market is small and it is difficult to predict demand.
This 2013 report from Medecins Sans Frontieres has more on the topic.
At least one third of the world's population are carriers of tuberculosis (TB), according to WHO. Many do not develop the disease as long as their immune systems remain healthy.
When someone has the HIV virus, their immune system is destroyed and they are at high risk of developing and dying from TB.
The international community is concerned about a strain of tuberculosis that is highly resistant to most antibiotics, and could spread and threaten the fight against both TB and AIDS. The so-called extensively drug-resistant (XDR) TB is lethal in the majority of cases.
There is no cure yet for HIV/AIDS, but there are treatments that contain the effects of the virus.
Drug cocktails known as highly active antiretroviral therapy, or HAART, have transformed HIV from a death sentence into a chronic condition that can be managed.
The drugs suppress the replication of HIV but cannot eradicate it from the body, so the patient has to take the treatment all their life.
Patients' drug cocktails must be changed from time to time, because the HIV virus mutates regularly and can develop resistance to a particular treatment.
Another issue is that the drugs need to be taken with regular meals and clean water to be fully effective. This is difficult in countries where people suffer frequent food and water shortages.
The number of people in developing countries receiving antiretroviral drugs has jumped since 2003 when WHO and UNAIDS launched a plan to roll out treatment, but the United Nations estimates that about two-thirds of those who need drugs still do not receive them.
The treatment plan is being funded through agencies including the U.S. President's Emergency Plan for AIDS Relief (PEPFAR), World Bank and the Global Fund to Fight AIDS, Tuberculosis and Malaria.
In 2010, the number of people qualifying for treatment rose significantly when WHO guidelines recommended that treatment begin earlier - before people become ill when their immune systems weaken. This early treatment can protect them from infections like tuberculosis - the main killer of people with HIV - and help prevent the spread of the virus, says WHO.
The guidelines were changed again in 2013, nearly doubling the number of people recommended for treatment.
Critics say the world's largest pharmaceutical companies, which have developed and now control the sale of the antiretroviral drugs, put profits before the lives of the poor by not making the treatments more widely and cheaply available.
However, the pharmaceutical giants often provide the drugs free or at greatly reduced cost, and argue that the drugs have to command a high price elsewhere to fund research into new treatments for the virus.
Medecins Sans Frontieres has produced a detailed breakdown of the cost of treatment.
Many of those on therapy in poor countries are taking generic drugs, most of them made in India.
Normally, inventors of new drugs have a 20-year monopoly on their medicines. But in 2001 the World Trade Organization (WTO) agreed that developing countries should be allowed to break drug patents and produce cheap generics to treat illnesses like HIV/AIDS.
The new WTO rules allowed countries to produce generics of drugs developed before 1995 and, as a result, the cost of antiretroviral drugs plummeted from over $10,000 per person per year to about $295 by mid-2001. The cost of these older drugs has continued to fall since.
The WTO rules also allowed countries to issue so-called "compulsory licensing" on drugs developed later, but these are complicated to introduce and take up a lot of government time. They also can create new problems as companies and countries that hold the original patents may be reluctant to invest in a country that's copying their products.
Thailand and Brazil issued these licences in 2006 and 2007, dramatically lowering the cost of their national treatment programmes.
One of the patent holders subsequently announced it would not market some of its newest drugs in Thailand, and the U.S. government put it on a "priority watch list" of countries committing intellectual property piracy.
India tightened up its patent regulations in 2005 to comply with WTO rules, forcing it to follow international patent laws more rigorously. Despite the WTO's 2001 ruling, this means Indian companies find it harder to produce copies of newer, often more effective drugs – with implications for thousands of patients in developing countries who depend on Indian generics for their survival.
These so-called second-line treatments are vital as patients become resistant to older drugs, but they are also a lot more expensive.
India makes the majority of the world's generic antiretrovirals, and Thailand, Brazil and South Africa also produce significant quantities. Other countries with their own HIV drug manufacturing facilities include Zambia, Ghana, Tanzania, Uganda, Zimbabwe and Kenya.
Vaccines and microbicides
Health experts hope that vaccines will eventually provide the final answer to HIV and AIDS.
A successful vaccine would be able to tell the human immune system to recognise HIV and launch a defence against it. If that happened, the vaccinated individual would be able either to destroy the virus completely or prevent it from progressing and being transmitted to others.
Scores of possible vaccines are being tested on human volunteers around the world, but many experts believe they are unlikely to succeed. Few of the trials are carried out in developing countries.
The International AIDS Vaccine Initiative (IAVI) says it is critical that developing countries host vaccine trials because the incidence of new HIV infections there is among the highest. In addition, the subtypes of HIV circulating in developing countries are different from those common in industrialised countries. Scientists do not yet know if or how different subtypes will affect a vaccine's effectiveness.
Cost is again a massive constraint. According to IAVI, the private sector is spending a tiny amount on developing an AIDS vaccine, compared with the total invested in medical research. This is mainly because the science is difficult, and the countries that need a vaccine most are least able to pay for the research and the finished product.
IAVI is campaigning for an increase in global spending on AIDS vaccine research. And organisations such as WHO are preparing for the distribution of an eventual vaccine in developing countries, amid fears that such a breakthrough would initially be widely available only in rich countries where the need is nowhere near as great.
Some companies and non-profit organisations are also working on microbicides, in the form of creams or gels, that can prevent infection by inactivating the virus during sex.
They could be lifesavers in cultures where women have little control over their sexual health - as they can be discreetly applied before sex without the consent of a partner. Several are being tested but are still years away from commercial use.
There are hundreds of organisations working on AIDS. Here is a list of some of the largest agencies:
Global Fund To Fight AIDS, Tuberculosis and Malaria. Formed in 2002 after the United Nations called for the creation of a global fund, it is a private foundation with a mandate to raise and disburse funds for AIDS, TB and malaria. It does not run projects itself, but has committed billions of dollars in scores of countries to fight all three diseases. It is a partnership between governments, civil society, the private sector and communities, with a secretariat in Geneva.
Joint United Nations Programme on HIV/AIDS (UNAIDS) is the key provider of strategic leadership, knowledge, policy advice and technical expertise on AIDS to the Global Fund.
U.S. President's Emergency Plan for AIDS Relief. Former U.S. President George W. Bush launched PEPFAR in 2003, as a means of channelling U.S. funding for HIV/AIDS programmes. It works with and provides billions of dollars for the Global Fund.
IAVI - International AIDS Vaccine Initiative. Founded in 1996, IAVI and its partners research and develop vaccines. It works with private companies, academics and government agencies.
Bill and Melinda Gates Foundation. Since its inception in 1994, the foundation has given billions of dollars in grants. Some go to U.S. projects, the rest support programmes in 100 other countries. Besides AIDS, money is allocated to tackling other health problems, such as malaria. The AIDS funding is channelled into the development of vaccines, microbicides and HIV prevention.
Sub-Saharan Africa has the highest HIV rates in the world. The majority of people with HIV live in this region, and many are not aware of their status.
AIDS is a leading cause of death in sub-Saharan Africa, and has been a key factor in lowering life expectancy in the worst-affected countries.
Women comprise 58 percent of people living with the virus in sub-Saharan Africa.
Experts are concerned about high infection rates among girls and young women. In South Africa, for example, 5.6 percent of girls aged 15 to 19 have HIV, rising to 17.4 percent of women aged between 20 and 24. HIV rates among adolescent boys are one fifth that rate.
Overall, new infections fell by a third between 2005 and 2013, and the number of deaths dropped by 39 percent in the same period.
Southern Africa is the worst-affected region, and South Africa has the world's highest caseload. UNAIDS says HIV prevalence in the region as a whole is levelling off, but at very high levels.
Ten countries in sub-Saharan Africa - Ethiopia, Kenya, Malawi, Mozambique, Nigeria, South Africa, Uganda, United Republic of Tanzania, Zambia and Zimbabwe - account for 81 percent of all HIV cases in the region. But many others have rates of less than 2 percent.
One of the main obstacles to preventing the spread of AIDS in Africa is social stigma, although this has begun to change as more HIV-positive Africans go public. Another is the risk of HIV infection among adolescent girls and young women.
Increased use and distribution of condoms, male circumcision, and HIV prevention programmes for injecting drug users, gay men and other men who have sex with men, and sex workers are important ways of preventing its spread. Greater access to antiretroviral treatment is also driving down new HIV infections, UNAIDS said.
South Africa has the world's largest number of people with HIV/AIDS. The government was widely criticised for dragging its feet over the epidemic, and for many years it rejected a public antiretroviral treatment programme, partly on cost grounds.
Former President Thabo Mbeki enraged activists by questioning the link between HIV and AIDS, and former Health Minister Manto Tshabalala-Msimang drew international criticism in 2006 for advocating traditional medicines - including garlic and beetroot - rather than antiretrovirals to fight HIV.
The government dropped its official objections in 2003. South Africa now has the world's largest HIV treatment programme, and has boosted AIDS education and access to testing and counselling.
South Africa recorded the largest fall in the number of new infections in sub-Saharan Africa, with 98,000 fewer in 2013 than in 2010.
The first case of AIDS was identified in Uganda in the early 1980s. The country has been hailed by many for its approach to containing the virus, with the infection rate peaking at 18 percent in the 1990s before plummeting to five percent by 2000.
The government quickly acknowledged the epidemic and began a public information campaign early on with the key message of "Zero Grazing" - avoid casual sex. It also adopted the ABC approach - "Abstain, Be faithful, use a Condom".
Much of the prevention work was done by grassroots organisations which educated people about HIV/AIDS by word of mouth, and helped break down the stigma associated with AIDS.
Behind all that was a strong political will to stop the spread of the virus, together with openness about HIV. Successive governments mobilised the entire population in the fight.
However, risky behaviour is on the rise again, and it is the only country in the region, apart from Angola, to record an increase in the number of new infections in 2013.
Asia has the second-highest number of people living with HIV after sub-Saharan Africa, but its overall prevalence rate is much lower.
The spread of HIV in Asia has been fuelled in part by the sex industry, with intravenous drug use and unprotected sex between men also factors, says UNAIDS.
Ignorance about AIDS and social stigma surrounding the disease and those in high-risk groups are also important driving forces behind the pandemic, says the World Bank.
As in other regions, women are increasingly at risk of infection from their partners.
India has the largest caseload.
In south and southeast Asia, the number of new infections fell by 8 percent between 2005 and 2013, according to a 2014 UNAIDS report. Myanmar, Thailand and Vietnam saw much greater drops – of between 45 and 58 percent.
New infections have soared in Indonesia.
UNAIDS/World Health Organization (WHO) figures for 2005 estimated that India had 5.7 million people living with HIV/AIDS. But government estimates in 2007 put the figure at 2.47 million. UNAIDS subsequently said this figure was probably more accurate.
Between 2005 and 2013, the number of infections fell by 19 percent.
However, AIDS activists have cautioned in the past that many people in rural areas may not know their status, while deaths due to AIDS are often ascribed to other diseases like tuberculosis.
AIDS officials in India say one of the biggest problems they face is combating misconceptions about how the virus is spread in a nation where open talk of sex is often frowned on.
China's epidemic is mainly driven by unprotected heterosexual sex, rather than injecting drug use as in the past - China has one of the world's largest number of injecting drug users.
Men who have unprotected sex with men are also an important factor, as is sex work - the majority of sex workers do not consistently use condoms, says UNAIDS.
E. Europe and C. Asia
The AIDS epidemic is growing fast in Eastern Europe and Central Asia.
The vast majority of the region's HIV/AIDS cases are injecting drug users and their sexual partners in the Russian Federation and Ukraine. Access to treatment is limited, particularly for drug users.
Ukraine has experienced a fall in the number of new HIV cases between 2005 and 2013. It is one the few countries in the region to provide HIV prevention services for people who inject drugs.
Sex workers and men who have sex with men are also vulnerable to the virus.
The biggest epidemic in Central Asia is in Uzbekistan, which straddles major drug-trafficking routes, and here the majority of cases are injecting drug users. As many rarely use a condom, there is a strong likelihood of the virus spreading to their partners.
UNAIDS has warned an increase in risky behaviour – drug use and unprotected sex – in the countries of the Caucasus and Central Asia could spark new epidemics across the region.
Turkmenistan could be among those most at risk due to a lack of sexual health education and poor medical facilities. However, the republic's isolation makes it almost impossible to obtain data on the number of infections there.
Latin America and Caribbean
Latin America has some of the developing world's best treatment coverage. Unprotected sex between men is the main driver of the epidemic in several countries. Sex workers and injecting drug users are also particularly vulnerable to new infections.
Prevention programmes tend to ignore both men who have sex with men, transgender people, and injecting drug users, and stigma and discrimination against people in these high-risk groups have helped drive the epidemic underground.
Brazil has the largest number of people living with HIV in Latin America, but its prevalence rate is among the lowest in the world. The country's prevention, testing and treatment programmes have been held up as a global model.
Widespread poverty and migration, lack of information about the epidemic in rural areas, and rampant homophobia have all contributed to the spread of AIDS.
The Caribbean is home to just 0.67 percent of the global number of cases, but infection rates are high. The majority of infected people live in Haiti.
The pandemic is mainly fuelled by the sex industry, according to UNAIDS, while unsafe sex between men is a smaller factor.
Men who have sex with men experience high infection rates. In Jamaica, a third are HIV-positive.
As with sub-Saharan Africa, infection rates are higher among young women than men. In Haiti, infection rates among women aged 20 to 24 are more than double those of men of the same age.
Cuba has managed to contain the epidemic, but using controversial methods including quarantining and forced testing which have been criticised by experts.
Brazil is regarded as a global model for prevention and treatment. Its prevalence rate has been a low and steady 0.5-0.6 percent since 2000, according to UNAIDS.
In the early 1990s it began promoting condom use rigorously - a campaign which is stepped up every year in the lead-up to the annual carnival.
Then in 1996 the government offered free HIV treatment to everyone, using Brazilian pharmaceutical companies to supply cheap generic drugs. The free treatment encouraged people to come forward for testing, knowing they would not face a potential death sentence. The country's treatment coverage is among the most comprehensive in the world.
Brazil's AIDS campaigns have attempted to ease discrimination against injecting drug users, people with HIV/AIDS and men who have sex with men. The country also promotes HIV testing, condom use, sex education and AIDS prevention in schools.
Cuba has been extremely successful in containing the virus - its prevalence rate is one of the lowest in the world at 0.1 percent. But the government has used controversial methods to prevent its spread.
When the country's first case emerged in the early 1980s, the government declared a public health emergency.
It forcibly quarantined people living with HIV, and traced and tested their sexual partners. It tested all Cubans who had visited Africa, as well as pregnant women. Those found to be HIV positive were given drugs to prevent transmission to their unborn children, and their babies were delivered by caesarean section.
At the same time a massive media and information campaign was launched to teach people about the virus and encourage them to use condoms.
Since then, the rules have been relaxed a little. There is no forced testing, but those in high-risk groups are strongly encouraged to volunteer.
Those found to be HIV positive attend a two-month education programme in a sanatorium. And the government maintains a database of those with HIV and their chain of sexual partners.
Until 2001 very few antiretrovirals were available on the island because of a U.S. trade embargo, with 100 people receiving treatment through donations, according to the World Health Organization. But in 2001 Cuban laboratories began making generic versions. Since then death rates have fallen dramatically.
Middle East and N. Africa
The Middle East and North Africa together form a region that has the lowest number of people living with HIV in the world, but the number of new infections is rising.
More than half of new infections are in Iran and Sudan.
In many countries, the virus has not yet moved into the general population. But experts at the World Health Organization (WHO), UNAIDS and World Bank say evidence from other regions shows this is probably just a question of time unless governments act soon.
As in other regions, the people most at risk are also the most marginalised and socially stigmatised – sex workers and their clients, men who have sex with men, intravenous drug users and their partners, and migrants.
Basic prevention programmes – such as condom promotion – are largely absent in the Middle East and North Africa, and treatment lags far behind other regions. Many experts are also worried there is not enough data collection, especially among high-risk groups like sex workers, to know how quickly the virus is spreading.
Some experts blame Islamic beliefs both for perpetuating stigma and curbing knowledge about the disease. In a region with conservative mores, and where discussion of extramarital sex is taboo, there is often little information available on how people can protect themselves. Social customs also mean governments are more likely to ignore the disease.
Others say Islam has prevented the spread of HIV through its promotion of abstinence until marriage and fidelity. Carla Makhlouf Obermeyer, a scientist with the WHO's HIV/AIDS department, said in 2006 that limited alcohol use and male circumcision may partly explain low prevalence among Muslim populations.
The Iranian government is one of the few in the region to take the epidemic seriously. It has publicised both the extent of HIV infection and the urgent need to control its spread.
It has also passed laws to protect the rights of people with HIV and reduce the social stigma attached to the illness. As recently as 2001, workers could be fired from their jobs for being HIV positive, and doctors and hospitals could refuse to treat AIDS patients.
School children now learn about the virus as part of their health education, and couples applying for marriage licences receive information on how to protect themselves from the disease.
Injecting drug use is the main form of transmission in Iran. UNAIDS considers the country's programme for users inside and outside prisons a global best practice model.
The government runs needle exchange programmes in high drug-use areas of Tehran, syringes are available over the counter in many chemists, and there are drug treatment centres across the country. The centres also provide food and shelter, employment, HIV/AIDS screening and treatment, and family counselling.
General information and statistics
The Joint U.N. Programme on HIV/AIDS, UNAIDS has all the latest statistics by country and region, and plenty of general information and reports about the virus, how it affects people, its prevention etc.
The World Health Organization has statistics, fact sheets and more detailed publications for health professionals.
The World Bank's AIDS site has information about how AIDS has affected developing countries' economies.
The U.N. Development Programme's AIDS website describes how the agency helps governments address the AIDS crisis.
The British-based Avert nongovernmental organisation provides detailed information by country and region, and on rolling out treatment in developing countries.
To find out about the leading agency distributing AIDS funds, visit the Global Fund to Fight AIDS, Tuberculosis and Malaria website.
Other important funding agencies are the U.S. President's Emergency Plan for AIDS Relief and the Bill and Melinda Gates Foundation.
If you're looking for information about vaccines and their production visit the International AIDS Vaccine Initiative website.
The International AIDS Society is a large, Geneva-based association of HIV/AIDS healthcare professionals. Scroll down to the World AIDS News section for a round-up of the latest medical news.
AmFar, the American Foundation for AIDS Research, has some information about medical research.
A huge number of international non-governmental organisations are dedicated to ending the pandemic, and supporting those whose lives have been affected by HIV/AIDS. Their websites contain stories of people living with the virus, and how community groups are working to improve their lives.
Here are just a few:
The British-based International HIV/Aids Alliance, which has a global partnership of nationally-based organisations working to support community action on AIDS.
The Amsterdam-based Global Network of People Living with HIV is a global alliance of AIDS activists, including those living with the virus.
Other international organisations working for better conditions and funding include: the International Council for AIDS Service Organisations, the US-based Global Health Council, the Clinton Foundation and the Global Business Coalition on HIV/AIDS, Tuberculosis and Malaria.
More campaigning organisations include the World AIDS Campaign.
Women and HIV
The Global Coalition on Women and AIDS (GCWA) has lots of information on how the disease affects women. The Coalition is a loose alliance of civil society groups, networks of women living with HIV, and U.N. agencies.
More information is available at the website of the International Community of Women Living with HIV/AIDS. Its membership is only open to HIV-positive women, and its newsletter includes some powerful contributions from women activists around the world.
Children and HIV
The Global Movement for Children is an umbrella organisation of groups working for children. It has useful information about children's access to HIV treatment.
The U.N. Children's Fund AIDS pages have useful country-by-country statistics, and an overview of the issues surrounding children and HIV.
News and research
A U.S.-based news site is AIDS.ORG. It is mainly aimed at the U.S. market, but also has some international stories.
For academic texts on the social, economic and political aspects of HIV/AIDS in developing countries, visit the Eldis Resource Guide on HIV and AIDS.
AIDS and humanitarian emergencies
Here is a useful report written by the Inter-Agency Standing Committee on HIV/AIDS, drawing up guidelines for HIV/AIDS interventions in emergency situations.