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close this bookGlobal HIV/AIDS Epidemic Update 1998 (UNAIDS, 1998, 18 p.)
View the document(introduction...)
View the documentGlobal summary of the HIV/AIDS epidemic, December 1998
View the documentAnatomy of the epidemic
View the documentA health crisis and beyond
View the documentHIV - a threat to the world’s young people
View the documentWhat drives the epidemic?
View the documentNote about UNAIDS/WHO estimates

Anatomy of the epidemic

Global summary

By the end of 1998, according to new estimates from the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO), the number of people living with HIV (the virus that causes AIDS) will have grown to 33.4 million, 10% more than just one year ago. The epidemic has not been overcome anywhere. Virtually every country in the world has seen new infections in 1998 and the epidemic is frankly out of control in many places.

More than 95% of all HIV-infected people now live in the developing world, which has likewise experienced 95% of all deaths to date from AIDS, largely among young adults who would normally be in their peak productive and reproductive years. The multiple repercussions of these deaths are reaching crisis level in some parts of the world. Whether measured against the yardstick of deteriorating child survival, crumbling life expectancy, overburdened health care systems, increasing orphanhood, or bottom-line losses to business, AIDS has never posed a bigger threat to development.

According to new UNAIDS/WHO estimates, 11 men, women and children around the world were infected per minute during 1998 - close to 6 million people in all. One-tenth of newly-infected people were under age 15, which brings the number of children now alive with HIV to 1.2 million. Most of them are thought to have acquired their infection from their mother before or at birth, or through breastfeeding.

While mother-to-child transmission can be reduced by providing pregnant HIV-positive women with antiretroviral drugs and alternatives to breastmilk, the ultimate aim must be effective prevention for young women so that they can avoid becoming infected in the first place. Unfortunately, when it comes to HIV infection, women appear to be heading for an unwelcome equality with men. While they accounted for 41% of infected adults worldwide in 1997, women now represent 43% of all people over 15 living with HIV and AIDS. There are no indications that this equalizing trend will reverse.

Altogether, since the start of the epidemic around two decades ago, HIV has infected more than 47 million people. And though it is a slow-acting virus that can take a decade or more to cause severe illness and death, HIV has already cost the lives of nearly 14 million adults and children.

An estimated 2.5 million of these deaths occurred during 1998, more than ever before in a single year.

AIDS and the infectious disease picture

According to recent WHO estimates, malaria causes over 1 million deaths a year. In 1998, AIDS deaths totalled some 2.5 million. Both diseases are among the five top killers worldwide. However, it is important not to overlook the dynamics in this picture. Already in 1954, millions of people were dying annually of malaria. AIDS is a still-emerging epidemic whose death toll rises every year, while the ranks of the newly infected swell by some 16 000 a day.

Tuberculosis, the second biggest infectious killer, is also on the rise, driven in large part by the HIV epidemic. People whose immune defences are weakened by HIV infection become an easy prey for other microbes, including the bacillus that causes tuberculosis. The resulting infections (along with some cancers) are responsible for the recurring illnesses which in their late stages are called “AIDS”, and which ultimately lead to death. Around 30% of all AIDS deaths result directly from tuberculosis.

While people undermined by HIV infection are more easily infected with the TB bacillus, many already harbour it from childhood. In either case, individuals with dual HIV/TB infection run a far greater risk than TB carriers who are HIV-negative that their tuberculosis will become active and potentially lethal. Worldwide, millions of people are already infected with both HIV and the tuberculosis bacillus, and the potential for further growth of co-infection in the developing countries is vast, given the crushing prevalence of TB carriers in the general population (some 30%) and the almost 6 million new HIV infections a year. Tackling the dual epidemics calls for stronger TB casefinding and treatment - tuberculosis can be cured with antibiotics regardless of whether the person is HIV-infected or not - in parallel with stronger AIDS prevention programmes to avert new HIV infections.

Regional roundup

Sub-Saharan Africa is home to 70% of the people who became infected with HIV this year. It is also the region in which four-fifths of all AIDS deaths occurred in 1998.

Africa, the global epicentre, continues to dwarf the rest of the world on the AIDS balance sheet. Since the start of the epidemic, 83% of all AIDS deaths so far have been in the region. Among children under 15, Africa’s share of new 1998 infections was 9 out of 10. At least 95% of all AIDS orphans have been African. Yet only a tenth of the world’s population lives in Africa south of the Sahara.

1 UNAIDS defines AIDS orphans as people who lost their mother or both their parents to AIDS when they were under the age of 15.

The sheer number of Africans affected by the epidemic is overwhelming. Since HIV began spreading, an estimated 34 million people living in sub-Saharan Africa have been infected with the virus. Some 11.5 million of those people have already died, a quarter of them children. In the course of 1998, AIDS will have been responsible for an estimated 2 million African deaths - 5500 funerals a day. And despite the scale of death, today there are more Africans living with HIV than ever before: 21.5 million adults and a further 1 million children.

While no country in Africa has escaped the virus, some are far more severely affected than others. The bulk of new infections continue to be concentrated in East and especially in Southern Africa.

The southern part of the African continent holds the majority of the world’s hard-hit countries. In Botswana, Namibia, Swaziland and Zimbabwe, current estimates show that between 20% and 26% of people aged 15–49 are living with HIV or AIDS. South Africa, which trailed behind some of its neighbours in HIV infection levels at the start of the 1990s, is unfortunately catching up fast: one in seven new infections on the continent this year are believed to be in this one country. Zimbabwe is especially hard-hit. There are 25 surveillance sites in the country where blood taken from pregnant women is tested anonymously as a way of tracking HIV infection. The most recent data, from 1997, show that in only 2 of these sites did HIV prevalence remain below 10%. In the remaining 23 sites, some 20–50% of all pregnant women were found to be infected. At least one-third of these women are likely to pass the infection on to their baby.

HIV and AIDS estimates, global and sub-Saharan Africa

Other areas of the continent are far from immune. One in ten adults or more are HIV-infected in Central African Republic, Cd’Ivoire, Djibouti and Kenya. In general, however, West Africa is less affected by HIV than Southern or East Africa, and some countries in Central Africa have also seen HIV remain relatively stable. Early and sustained prevention efforts can be credited with these lower rates in some cases - Senegal provides a good example. But elsewhere, where far less has been done to encourage safer sex, the reasons for the relative stability remain obscure. Research is under way to explain the differences between epidemics in various countries. These studies are looking into factors that may play some role, such as patterns of sexual networking, levels of condom use with different partners, and treatment of other sexually transmitted diseases (STDs), which if left untreated make it easier for HIV to pass through sexual intercourse.

Increasingly, the spotlight is on the spread of HIV through the Asian continent, especially in South Asia and East Asia. While rates remain low relative to some other regions, well over 7 million Asians are already infected and HIV is clearly beginning to spread in earnest through the vast populations of India and China.

India provides an interesting example of the shifting patterns of HIV.

· Until recently, it was commonly assumed that HIV infection in the world’s second most populous nation was concentrated in urban sex workers and their clients and in drug injectors living in a few states. The last round of sentinel surveillance in antenatal clinics shows that in at least in five states, more than 1% of pregnant women in urban areas are now infected.

· India’s rural areas - home to 73% of the country’s 930 million people - were thought to be relatively spared by the epidemic. Again, new studies show that at least in some areas, HIV has become worryingly common in villages as well as cities. A recent survey of randomly selected households in Tamil Nadu found that 2.1% of the adult population living in the countryside had HIV, as compared with 0.7% of the urban population. For this small state, with its population of 25 million, the study findings suggest that there are close to half a million people already infected with HIV in Tamil Nadu. Considering that nearly 10% of the people surveyed had gonorrhoea, syphilis or another sexually transmitted disease, HIV clearly has fertile ground for further spread.

· The virus is firmly embedded in the general population, among women whose only risk behaviour is having sex with their own husbands. In a study of nearly 400 women attending STD clinics in Pune, 93% were married and 91% had never had sex with anyone but their husband. All of these women were infected with a sexually transmitted disease, and a shocking 13.6% of them tested positive for HIV.

Regional HIV/AIDS statistics and features, December 1998


Epidemic started

Adults & children living with HIV/AIDS

Adults & children newly infected with HIV

Adult prevalence rate

Percent of HIV-positive adults who are women

Main mode(s) of transmission for adults living with HIV/AIDS

Sub-Saharan Africa

late ‘70s - early ‘80s

22.5 million

4.0 million




North Africa & Middle East

late ‘80s

210 000

19 000



IDU, Hetero

South & South-East Asia

late ‘80s

6.7 million

1.2 million




East Asia & Pacific

late ‘80s

560 000

200 000



IDU, Hetero, MSM

Latin America

late ‘70s - early ‘80s

1.4 million

160 000



MSM, IDU, Hetero


late ‘70s - early ‘80s

330 000

45 000



Hetero, MSM

Eastern Europe & Central Asia

early ‘90s

270 000

80 000




Western Europe

late ‘70s - early ‘80s

500 000

30 000




North America

late ‘70s - early ‘80s

890 000

44 000



MSM, IDU, Hetero

Australia &New Zealand

late ‘70s - early ‘80s

12 000






33.4 million

5.8 million



2 The proportion of adults (15 to 49 years of age) living with HIV/AIDS in 1998, using 1997 population numbers.

3 MSM (sexual transmission among men who have sex with men), IDU (transmission through injecting drug use), Hetero (heterosexual transmission).

In Eastern Europe and in Latin America and the Caribbean, infections are concentrated in marginalized groups though clearly not limited to them.

In Latin America the pattern of HIV spread is much the same as in industrialized countries. Men who have unprotected sex with other men and drug injectors who share needles are the focal points of infection. In Mexico studies suggest that up to 30% of men who have sex with men may be infected; among drug injectors in Argentina and Brazil the proportion may be close to half. While transmission through sex between men and women is on the rise, especially in Brazil, heterosexual HIV spread is especially prominent in the Caribbean. Prevalence rates of 8% among pregnant women have been reported from Haiti and one surveillance site in the Dominican Republic.

HIV continues to gallop through drug-injecting communities in Eastern Europe and Central Asia. A region which until the mid-1990s appeared to have been spared the worst of the epidemic, it now holds an estimated 270 000 people living with HIV. For the moment Ukraine remains the worst-affected country, though the Russian Federation, Belarus and Moldova have all registered enormous increases in the past few years. With HIV gaining new footholds as it penetrates new drug-user communities, the potential for continued spread through drugs and sex is undeniable given the known overlap between drug-injecting and sex-worker populations and the dramatic rises in other STDs. In the Russian Federation, for example, syphilis rates have shot up from around 10 cases per 100 000 people in the late 1980s to over 260 cases per 100 000 a decade later.

In North America and Western Europe, new combinations of anti-HIV drugs continue to reduce AIDS deaths significantly. For example, recently-published figures show that in 1997 the death rate for AIDS in the United States was the lowest in a decade - almost two-thirds below rates recorded just two years earlier, before combination therapy came into widespread use. However, because new infections continue to occur while antiretroviral drug cocktails keep already-infected people alive, the proportion of the population living with HIV has actually grown. This obviously increases the demands for care. In a number of less obvious ways, it adds to countries’ prevention challenges.

During 1998, North America and Western Europe recorded no progress in reducing the number of new infections. The early dramatic rises in HIV were successfully reversed by the mid-to-late 1980s thanks to prevention campaigns that raised condom use among gay men from virtually zero to well over 50%. But over the last decade, the rate of new infections has remained stable instead of continuing to decrease. During 1998 alone, nearly 75 000 people became infected with HIV, bringing the total number of North Americans and Western Europeans living with HIV to almost 1.4 million.

Clearly, the epidemic is no longer out of control in these countries. Just as clearly, it has not been stopped. And at this stage the prevention challenges are greater than ever. One reason is that prevention efforts have already reached the easier-to-reach groups, such as the largely well-educated and well-organized white gay communities. Another reason is that HIV infections are increasingly concentrated in the poorer sectors of the population. In the USA, to take one example, HIV has become a disproportionate threat to US citizens of African origin. Although African-Americans represent only 13% of the total US population, they bear an undue share of American poverty, underemployment and inadequate health care access. African-Americans are now more than 8 times as likely as whites to have HIV. According to the Centers for Disease Control and Prevention (CDC), among black males national HIV prevalence is estimated to have reached 2% and AIDS has become the leading killer in the 25–44 age group. For black women in the same age group, AIDS takes second place as cause of death. The US administration has just announced a new $156 million federal effort for minority communities to help curb HIV spread through drug injecting and sex, and to help ensure access to antiretroviral drug therapy for those already living with HIV.


Further details about regional patterns of HIV infection, together with end-1997 estimates of HIV infection and AIDS deaths for 170 individual countries, can be found in the UNAIDS/WHO publication Report on the global HIV/AIDS epidemic - June 1998. These country-specific estimates are the most recent ones available.

4 The report is available on the Internet at