Global epidemiology of hiv infection and aids

Global Epidemiology of HIV Infection and AIDS JOHN D. STRATIGOS, MD EVANGELIA TZALA, MSc

T

he AIDS epidemic is now more than a decade old, and new estimates by the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) indicate that infection with HIV is far more common in the world than previously thought.1 By the beginning of 1998 over 30 million people were living with HIV/AIDS (Table 1). That is one in every 100 sexually active adults aged 15 to 49 years old, yet only a tiny fraction know about their infection. During 1997 alone it is estimated that 5.8 million new HIV infections occurred (that is an average of 16,000 new infections daily during the year) despite the fact that more is known now than ever about preventing spread of the epidemic. Over 90% of these individuals are concentrated in the developing world, mostly in countries least able to afford to care for infected people. Over 50% of the newly infected adults are in the age bracket 15 to 24 years old and more than 40% are women. Overall, by the beginning of 1998, it is estimated that over 12 million women are living with HIV/AIDS, of whom 2 million were infected in 1997 alone (Table 1). The global HIV epidemic in women continues to expand at an alarming rate. The primary risk factor for HIV infection in women is unprotected heterosexual intercourse. Several cofactors may influence a women’s risk for acquisition, including the presence of other STDs, the prevalence of HIV in the population engaging in high-risk sexual behaviors at a young age, and the increased number of sexual partners.2 Of the 30 million people living with HIV/AIDS, 1.1 million are children under 15 years of age. Both UNAIDS and WHO estimate that the number of children who have been infected with HIV since the start of the epidemic has reached about 3.8 million, of whom 2.7 million have already died (Table 1). Nearly 600,000 children were infected with HIV in 1997. The overwhelming majority of these children live in the developing world and acquired the infection from their From the Department of Dermatology, University of Athens, and Hellenic Center for Infectious Disease Control, Athens, Greece. Address correspondence to Evangelia Tzala, MSc, HIV/AIDS Epidemiology Section, Hellenic Centre for Infectious Diseases Control (KEEL), 6-8 Macedonias Street, GR 104 33 Athens, Greece. © 2000 by Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010

mothers during pregnancy, during delivery, or through breast feeding. It is estimated that altogether 11.7 million people died of AIDS and HIV-related causes since the beginning of the epidemic and 2.3 million deaths occurred during the course of 1997 (Table 1). Community studies in less developed countries show a two- to threefold increase in total adult mortality, with an even larger increase in mortality among young adults in communities with adult HIV prevalence levels below 10%.3,4 HIV/AIDS is among the top ten leading causes of death worldwide, and according to the current situation of HIV infection, it may soon move into the top five.5 In the United States, after combination therapy was introduced in 1996, AIDS dropped into second place for the first time since 1992 as the leading cause of death in people 25 to 44 years old. It is apparent that AIDS is systematically cutting down life expectancy in the countries where the disease is most common. In a study of a rural area of Uganda, which has an adult HIV prevalence of 8%, life expectancy has dropped from just under 60 years to 42.5 years.6 There is evidence that HIV-infected women die at an earlier age than HIV-infected men and thereby lose significantly more productive years of life.3 In addition, the high mortality of AIDS and HIVrelated causes has major impacts on families. Both UNAIDS and WHO estimate that more than 8 million children under the age of 15 have lost their mothers to AIDS since the start of the epidemic and many of these have also lost their fathers (Table 2). It is estimated that this figure will double by the year 2000. Life expectancy in children has already been greatly affected by HIV. Despite the fact that developing nations have made great efforts in increasing infant and child survival in recent years, these gains are threatened by HIV. A mortality rate of 25% in babies under 12 months old was observed in Zimbabwe and Zambia because of HIV. Zimbabwe’s infant mortality rate is expected to rise by 138% because of AIDS by the year 2010.7 It is becoming increasingly apparent that, although almost every country is touched by HIV, the features of the pandemic differ from country to country (Fig 1). Variations in prevalence reflect the timing of the emer0738-081X/00/$–see front matter PII S0738-081X(99)00133-9

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Table 1. Global Estimates of the HIV/AIDS Epidemic as of December 1997 People newly infected with HIV in 1997

Number of people living with HIV/AIDS

AIDS deaths in 1997

Total number of AIDS deaths since the beginning of the epidemic

Total Adults Women Children ⬍15 Total Adults Women Children ⬍15 Total Adults Women Children ⬍15 Total Adults Women Children ⬍15

years

years

years

years

5.8 million 5.2 million 2.1 million 590 000 30.6 million 29.4 million 12.2 million 1.1 million 2.3 million 1.8 million 800 000 460 000 11.7 million 9.0 million 3.9 million 2.7 million

Source: UNAIDS–WHO. Report on the global HIV/AIDS epidemic, June 1998.

gence of HIV infection in the population, the rates of growth of the epidemic, and the sizes and types of the groups at risk (Table 2). Figure 2 shows the proportional increase among HIV prevalence rates in different countries between 1994 and 1997. As can be seen, there are more important changes in patterns of spread. It is clear that infection rates are rising rapidly in much of Asia, Eastern Europe, and Southern Africa. The picture in Latin America is mixed, with prevalence in some countries rising markedly. In other parts of Latin America and many industrialized countries, infection is falling or almost stabilizing. This is also the case for Uganda, one of the first

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countries hit by HIV and also for some West African nations and for Thailand, where the rapid spread of HIV has been checked by active prevention programs. However, although the situation is improving among many groups, large numbers of new infections occur in these countries annually.

Regions Sub-Saharan Africa Nearly 21 million adults and children, more than twothirds of the total number of people worldwide living with HIV, reside in Africa south of the Sahara Desert, and just over 80% of the AIDS deaths worldwide have been in this region. Most infections (80% to 90%) among adults have been acquired through unprotected sex between men and women paralleled by high level of other sexually transmitted diseases.8 Unprotected heterosexual contact accounted for most of the 3.4 million new HIV infections estimated among adults in sub-Saharan Africa in 1997. It has been demonstrated that mobility is an independent risk factor for the spread of HIV. Infections spread quickly from towns and cities into rural areas along trade routes assisted by long-distance lorry drivers, businessmen, migrant workers, and traders having sexual contact with local commercial sex workers.9,10,11 Estimates of HIV/AIDS show that women are more heavily affected in Africa than in other regions, where the virus initially spread most quickly among men by male-to-male sex or IV drug use.12 Four out of five HIV-positive women in the world live in Africa.

Table 2. Regional HIV/AIDS Statistics and Features as of December 1997

Region

Epidemic Began 1970s–early 1980s 1980s 1980s 1980s

Adults and Children Living With HIV/AIDS

Adult Prevalence Rate*

20.8 million 210,000 6.0 million 440,000

7.4% 0.13% 0.6% 0.05%

Percent of HIV-Positive Women ⬎16 Years

Main Model(s) of Transmission for Adults Living With HIV/AIDS‡

7.8 million 14,200 220,000 1,900

50% 20% 25% 11%

Heterosexual IDU, Heterosexual Heterosexual IDU, Heterosexual, Homosexual men Homosexual men, IDU, Heterosexual Heterosexual, Homosexual men IDU, Homosexual men Homosexual men, IDU Homosexual men, IDU, Hetersexual Homosexual men, IDU

Cumulative no. of Orphans†

Sub-Saharan Africa North Africa and Middle East South Asia and Southeast Asia East Asia and Pacific

Late Late Late Late

Latin America

Late 1970s–early 1980s

1.3 million

0.5%

91,000

19%

Caribbean

Late 1970s–early 1980s

310,000

1.9%

48,000

33%

Eastern Europe and Central Asia Western Europe North America

Early 1990s Late 1970s–early 1980s Late 1970s–early 1980s

150,000 530,000 860,000

0.07% 0.3% 0.6%

30 8,700 70,000

25% 20% 20%

Australia and New Zealand Total

Late 1970s–early 1980s

12,000 30.6 million

0.1% 1.0%

300 8.3 million

5% 41%

* The proportion of adults living with HIV/AIDS in the adult population (15 to 49 years of age). † Orphans are defined as HIV-negative children who lost their mother or both parents to AIDS when they were under the age of 15. ‡ IDU: intravenous drug use. Source: UNAIDS–WHO. Report on the global HIV/AIDS epidemic, June 1998.

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Figure 1. Estimated number of adults and children living with HIV/AIDS as of December 1997 Global total: 30.6 million. Source: UNAIDS–WHO. Report on the global HIV/AIDS epidemic, June 1998.

In addition, high fertility combined with breast feeding (nearly all children in Africa are breast-fed) and poor access to antiretroviral treatment, which helps reduce transmission from mother to child before and around childbirth, resulted in some 530,000 infected children being born to HIV-positive mothers in 1997. This figure accounts for roughly 90% of the world total. Moreover, an estimated 87% of the children living with HIV globally are in Africa. Although heterosexual transmission accounts for

most infections throughout Africa, levels of infection vary widely across the continent. In the beginning of the epidemic in the early 1980s, there were countries that remained apparently untouched by HIV; however, at the end of 1997, HIV has been recorded all across the African continent. Today, the most severely affected countries of the world are the southern nations of Africa where the virus is still spreading rapidly. By early 1998, 2.9 million South Africans are thought to be living with HIV, of

Figure 2. Proportional increase in country HIV prevalence rates between 1994 and 1997. Source: UNAIDS–WHO. Report on the global HIV/AIDS epidemic, June 1998.

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whom 700,000 were infected in 1997 alone. Other countries in southern Africa face even higher rates of infection. In Zimbabwe, one adult in four in 1997 was thought to be infected, and in Beit Bridge, a major commercial farming centre in Zimbabwe, HIV prevalence in pregnant women shot up from 32% in 1995 to 59% in 1996.13 In West Africa the rates of infection show signs of stabilization at much lower levels than eastern and southern Africa.12 Exceptions to this rule exist, however. In Coˆte d’Ivoire, one in 10 adults is believed to be living with HIV, and in Nigeria, where the estimated prevalence is relatively low by the standards of the continent (4.1%), there is no evidence that infection levels have stabilized. East Africa was one of the first areas to suffer a massive regional epidemic. There is some evidence (1997 data currently being analyzed by UNAIDS and WHO) that transmission of HIV has declined in 1997 (infection levels between 5% and 9%) to about one-fifth compared with 1996. Uganda is a country where HIV education has been especially vigorous,14 and this educational program seems to be paying off. This is especially so in the younger age groups, showing that young people nowadays are adopting safer sexual behavior.

South Asia and Southeast Asia By early 1998, South Asia and Southeast Asia accounted for an estimated 5.8 million (19%) of the 30.6 million adults and children living with HIV worldwide, with women being about one-third of the adults living with HIV in the region. The spread of HIV in this region began in the early to mid-1980s, but until the late 1980s no country in Asia experienced a major epidemic. Since then, however, it has become evident that the transmission of HIV was increasing among several populations, in some cases with great velocity, and that two sets of factors strongly influenced the course of the emerging epidemics: participation in sex work and patterns of intravenous drug use (IDU). Because the epidemic is more recent in Asia than in Africa, only a few countries in the region have developed sophisticated systems for monitoring the spread of the virus. Thus, HIV estimates in Asia often have to be made on the basis of less information than in other regions. The HIV epidemics in Asia are diverse, localized, and have different trends over time.15 In China, where the number of people living with HIV is thought to have doubled in 1997 as compared to 1996, two major epidemics are under way. One is among IV drug users in the mountainous southwest of the country and the other and newer epidemic is among heterosexuals, especially along the prosperous eastern seaboard where

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prostitution is re-emerging as the gap grows between rich and poor.16 In India, infection rates of under 1% of the total adult population are still low by the standards of many countries. There is evidence of infection among IV drug users and male and female commercial sex workers, but little is known about the levels of infection in the general population in this large and diverse country where patterns of infection are likely to differ widely.17 Today, it is estimated by UNAIDS and WHO that about 4 million people in India are living with HIV, and this makes India the country with the largest number of HIV-infected inhabitants in the world. Information about HIV infection in other parts of South Asia is limited, but it is clear that many people are practicing unprotected sex.13 Rates of HIV infection remain low in several South Asian and Southeast Asian countries. In Bangladesh, Indonesia, Laos, Pakistan, the Philippines, and Sri Lanka, infection rates are kept lower than 1 adult in 1000 yet; however, other countries in the region—including Cambodia, Myanmar, Thailand, and Viet Nam—show much higher levels of HIV infection. In Thailand, where the epidemic has been the best described in the developing world, HIV is believed to have spread through IV drug users and commercial sex workers and their clients. Health education and sustained prevention efforts have resulted in a decline in new infections, especially among sex workers and their patrons.18 Overall, about 6.4 million people are currently believed to be living with HIV in Asia and in the Pacific countries—just over 1 in 5 of the world’s total. It is expected that by the end of the year 2000, that proportion will grow to 1 in 4. It is also estimated that about 94,000 children in Asia now live with HIV.

Latin America and the Caribbean Over 1.3 million people are believed to be living with HIV in Latin America and the Caribbean. HIV prevalence is estimated at under 1 adult in 100 in all, but the picture in the region is heterogeneous. In some places there is clear evidence of increasing infection among neglected, socially, and economically marginalized populations. The pattern of HIV spread in Latin America is much the same as that in industrialized countries. Sexual transmission from man to man and IV drug use are the main modes of HIV transmission. Data from Mexico suggest that up to 30% of men who have sex with men may be living with HIV. Rates in drug users vary from 3% to 11% in Mexico to close to 50% in Argentina and Brazil.16 Nevertheless, heterosexual transmission is becoming more prominent. The number of women infected has

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increased. In Brazil, the male/female ratio of AIDS cases has dropped from 16:1 in 1986 to 4:1 in 1997.16 Although HIV prevalence is kept at low levels in the region, AIDS has already had a major impact. In Mexico, AIDS was the third leading cause of death in men between 25 and 34 years of age in 1995, with increasing trends.1,16 In Sao Paulo, Brazil, AIDS became the leading cause of death in 20 –34-year-old women in 1992.1,19 In Latin America and the Caribbean as a whole, AIDS has already overtaken traffic accidents as a cause of death; however, a recent decline in AIDS mortality, due to the increasing use of antiretroviral therapy, has been recorded in Sao Paulo.

North America Some 860,000 adults and children are believed to be living with HIV in North America. Infections acquired through unprotected sex between men have accounted for half of the AIDS cases reported in this region. Infection rates are continuing to increase in this group, especially in younger men. More recently, HIV has been spreading through IV drug use, but the largest proportional increase in reported AIDS causes has been through heterosexual exposure. In the United States, data indicate that the first-ever annual decline in both new AIDS cases and deaths among persons reported with AIDS occurred in 1996 and 1997 by 7% and 25%, respectively.20 The largest decrease (11%) was in homosexual men; however, AIDS continues to rise in some disadvantaged sections of the society. New AIDS cases rose by 19% in 1996 among heterosexual African-American men and 12% among heterosexual African-American women. An increase of 13% in men and 5% in women was recorded for the Hispanic community. This may result both from the difficulty that these communities encounter in accessing the expensive but effective antiretroviral combination therapies and the prevention efforts that have been less successful in minority communities where transmission is often through heterosexual intercourse and IV drug use.

Europe Some 670,000 adults and children are believed to be living with HIV in Europe; however, epidemic trends are different between Western and Central Europe and Eastern European countries. Overall AIDS trends are driven by trends in Western Europe, which continues to account for over 90% of the annual AIDS incidence in the WHO European Region. In Western Europe, a sharp decline in AIDS incidence occurred in 1996. For the first time since the start of the epidemic, the AIDS incidence dropped by 12% and continued to fall by 27% in 1997. Marked declines have occurred in all three main transmission groups: homosexual men, IV drug users, and heterosexually

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infected persons. The largest declines were observed in women (1997; IDU: 36% in women vs. 30% in men; heterosexuals, 27% in women vs. 17% in men).21,22 This decrease is partly attributable to prevention measures taken, but is probably due most of all to new and effective antiretroviral drug therapies that postpone the development of AIDS and prolong the life of those living with HIV.22 In Central Europe, excluding Romania, there is no evidence from AIDS or other available data that emerging epidemics are developing. In contrast, in Eastern Europe large HIV outbreaks affecting essentially IDUs have emerged since 1995. Specifically, in Ukraine the number of newly diagnosed HIV infections rose explosively from less than 50 per year (mostly foreigners) until 1994 to 1499 in 1995 and to 12,228 in 1996.22,23 The Ukrainian epidemic has been rapidly followed by epidemics among IDUs in other former communist countries. Although most of these epidemics are not yet detectable through AIDS surveillance, it is likely that tens of thousands of individuals have been infected with HIV in Eastern Europe over the past 2 years. The potential for sexual spread also exists in many areas in Eastern Europe. In the former Soviet Union, reported syphilis rates have increased extremely rapidly since 1991. In many countries, rates were as high as 120 to 170 per 100,000 population in 1995, a 15- to 30-fold increase compared to 1990 rates.24 This increase continued through 1996, and in the Russian Federation (the former Soviet Union) the annual rate reached 260 cases per 100,000 population.25

North Africa and the Middle East Just over 200,000 people are estimated to be living with HIV in this region, but there is not enough information about HIV infection rates. Some countries, particularly those with large populations of immigrant workers, carry out mass screening for the virus, and none of them estimate infections at more than one adult in 100. Risky behavior does exist, however, and there are countries in the region that have started programs to reduce risky drug-injecting practices. Additionally, in some countries in the region both community and nongovernmental organizations educate sex workers and others with risky behavior to protect themselves against HIV.

Comments Innovative antiretroviral therapies have been shown to prolong survival in HIV-infected people. Although it is clear that these therapies do not work for everyone and it is not yet known for how long they will prolong life, their use has resulted in significant declines in AIDS incidence and AIDS mortality.26 –28 Overall, these developments have resulted in signif-

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icant changes both to the therapeutic management of the disease 29,30 and to the existing surveillance system, which until now has been used to monitor and characterize the epidemic.31–33 Confidential reporting of newly diagnosed HIV infections (HIV case reporting) has been either implemented or will be implemented in several countries around the world, namely the United States of America and the nations of the WHO European Region. National HIV surveillance systems running in parallel with the multiple surveillance tools that have been used to monitor the HIV/AIDS epidemic would improve our understanding of the epidemic, help to target prevention and public health services, provide a link to health and social services, and result in better allocation of resources.34 –37 These developments, however, concern the industrialized countries of the world as many countries with the highest rates of HIV infection have little or no access to antiretroviral therapy. Such therapies are expensive, hard to administer, require regular monitoring, and therefore present with difficulties not only among but within nations in their provision to HIV-infected people. The annual worldwide cost of making triple combination antiretroviral therapy widely available to HIVinfected adults and children in all nations was estimated at the end of 1997 to be $65.8 billion.38 In the same study, it was demonstrated that the potential economic cost, especially in countries with limited financial resources, would be prohibitively expensive at current prices. Specifically, the potential cost of antiretroviral therapy would exceed the per capita national health expenditures of many countries, in particular in sub-Saharan Africa. Despite the severe financial strain, it was demonstrated that these countries would be the ones with the most to gain from the widespread availability of antiretroviral therapy.38 Because life expectancy in these countries and especially in Africa has already been greatly affected by HIV, any sizable reduction in AIDS mortality would likely be associated with substantial improvements in life expectancy and reduction in adult mortality.3– 6 Furthermore, the rate of vertical transmission of HIV could be greatly reduced with antiretroviral treatment as a short course of zidovudine has been shown to be a cost-effective measure in preventing perinatal HIV exposure in sub-Saharan Africa.39,40 In France and the United States, where zidovudine therapy given to the mother and the neonate is widespread, less than 5% of children born to HIV-positive women in 1997 were HIV infected. The average percentage in the developing countries was between 25% and 35%.41 Of course, one reason is the access to antiretroviral drugs and the other is the differences in breast-feeding practices. In summary, the current global HIV/AIDS situation

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and the fact that antiretroviral drugs are not affordable and available for treating vast numbers of HIV-positive individuals around the world demonstrate that primary prevention of HIV infection should remain the important concept in controlling the epidemic. Although the provision of adequate care for HIV-positive people is essential, preventing HIV from spreading in the first place is the most effective way of reducing the impact of the epidemic on families, communities, and society. The current declines in AIDS incidence observed in industrialized nations must certainly not be seen as a reason for reducing control activities, and prevention efforts must be maintained by all means. In countries where large epidemics have developed, preventing further spread of HIV through behavioral interventions and control of bacterial STD is a major aspect. Moreover, in the countries where large epidemics have not developed, further spread of HIV is a constant threat, and prevention measures must continue and be strengthened. Worldwide experience has shown that epidemics, once triggered, can develop extremely rapidly. Evidence up to now suggests that prevention does work. Data from the United Kingdom show that the collection of intervention approaches had a significant impact on the behavior of IV drug users and has helped prevent an epidemic of HIV infection among IDUs.42 In Thailand, disease prevention worked despite the fact that the epidemic was already in a phase of rapid growth. The Thailand data demonstrate a dramatic decrease in the incidence of rates of STDs, including HIV infection, among young men in military service and who were between 19 and 23 years of age.18,43 The examples cited here add to the growing evidence of the significance of early interventions in encouraging behavior change and thus limiting the spread of HIV infection.

References 1. UNAIDS–WHO. Improving estimates. Report on the global HIV/AIDS epidemic, June 1998. 2. Fowler MG, Melnick SL, Mathieson BJ. Women and HIV. Epidemiology and global overview. Obstet Gynecol Clin North Am 1997;24:705–29. 3. Boerma JT, Nunn AJ, Whitworth JA. Mortality impact of the AIDS epidemic: Evidence from community studies in less developed countries. AIDS 1998;12(Suppl 1):S3–14. 4. Timaeus I. Impact of the HIV epidemic on mortality in sub-Saharan Africa: Evidence from national surveys and censuses. AIDS 1998;12(Suppl 1):S15–27. 5. UNAIDS–WHO. HIV and mortality. Report on the global HIV/AIDS epidemic, June 1998. 6. Nunn AJ, Mulder DW, Kamali A, et al. Mortality associated with HIV-1 infection over five years in a rural Ugandan population: Cohort Study. BMJ 1997;315:767–71. 7. UNAIDS–WHO. Report on the global HIV/AIDS epidemic, December 1997.

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8. Grosskurth H, Mosha F, Todd J, et al. Impact of improved treatment of sexually transmitted diseases on HIV infection in rural Tanzania: Randomized controlled trial. Lancet 1995;346:530 – 6. 9. WHO. HIV/AIDS. The global epidemic, December 1996. Wkly Epidemiol Rec 199;72:17–21. 10. Davison K, Nicoll A. The changing global epidemiology of HIV infection and AIDS. Commun Dis Rep CDR Wkly 1997;7:R134 – 6. 11. Mertens TE, Belsey E, Stoneburner RL. Global estimates and epidemiology of HIV-1 infections and AIDS: Further heterogeneity in spread and impact. AIDS 1995;9(Suppl A):S259 –72. 12. UNAIDS–WHO. HIV/AIDS estimates and indicators, end 1997. Report on the global HIV/AIDS epidemic, June 1998. 13. UNAIDS–WHO. HIV and AIDS: The global situation. Report on the global HIV/AIDS epidemic, June 1998. 14. STD/AIDS Control Programme at Ministry of Health, Uganda. A report on declining trends in HIV infection rates in sentinel surveillance sites in Uganda. Kampala: Ministry of Health, 1996. 15. Monitoring the AIDS Pandemic (MAP). Final report on the status and trends of the HIV/AIDS/STD epidemics in Asia and the Pacific. Official Symposium of the 4th International Conference on AIDS in Asia and the Pacific. October 25–29, 1997, Manila, Philippines. 16. UNAIDS–WHO. The evolving picture region by region. Report on the global HIV/AIDS, June 1998. 17. Lalvani A, Shastri JS. HIV epidemics in India: Opportunity to learn from the past. Lancet 1996;347:1349 –50. 18. Nelson KE, Celentano DD, Eiumtrakol S, et al. Changes in sexual behaviour and a decline in HIV infection among young gay men in Thailand. N Engl J Med 1996;335:297–303. 19. Carvalheiro CD, Manco AR. Mortality among women for reproductive age in an urban area of the south-eastern region of Brazil. Evolution in the past 20 years. Rev Saude Publica 1992;Aug 26:239 – 45. 20. CDC. US HIV and AIDS cases reported through December 1997. HIV/AIDS Surveillance Report 1997;9:1–38. 21. European Centre for the Epidemiological Monitoring of AIDS. HIV/AIDS Surveillance in Europe: Quarterly report no. 57. Saint-Maurice: WHO-EU, 1998. 22. Hamers FF, Downs AM, Infuso A, et al. Diversity of the HIV/AIDS epidemic in Europe. AIDS 1998;12(Suppl A): S63–70. 23. Hamers FF, Batter V, Downs AM, et al. The HIV epidemic associated with IDU in Europe: Geographic and time trends. AIDS 1997;11:1365–74. 24. Gromyko A. Sexually transmitted diseases epidemic in eastern Europe: A call for help. Entre Nous 1996;33:7– 8. 25. Tichonova L, Borisenko K, Ward H, et al. Epidemics of syphilis in the Russian Federation: Trends, origins, and priorities for control. Lancet 1997;350:210 –3. 26. Hogg RS, O’Shaughnessy MV, Gataric N, et al. Decline in deaths from AIDS due to antiretrovirals (letter). Lancet 1997;49:1294. 27. Hogg RS, Heath KV, Yip B, et al. Improved survival among HIV-infected individuals following initiation of antiretroviral therapy. JAMA 1998;279:450 – 4.

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28. Palella FJ Jr, Delaney KM, Moorman AC, et al. Declining morbidity and mortality among patients with advanced human immunodeficiency virus infection. HIV Outpatient Study Investigators. N Engl J Med 1998;338:853– 60. 29. Carpenter CC, Fischl MA, Hammer SM, et al. Antiretroviral therapy for HIV infection in 1996: Recommendations of an international panel. International AIDS Society– USA. JAMA 1996;276:146 –54. 30. Therapeutic guidelines for the treatment of HIV/AIDS and related conditions. Vancouver: BC Centre for Excellence in HIV/AIDS, 1995. 31. Gostin LO, Ward JW, Baker AC. National HIV case reporting for the United States—a defining moment in the history of the epidemic (letter). N Engl J Med 1997;337: 1162–7. 32. Centers for Disease Control and Prevention. Update: Trends in AIDS incidence—United States, 1996. MMWR Morb Mortal Wkly Rep 1997;46:861–7. 33. European Centre for the Epidemiological Monitoring of AIDS: AIDS Surveillance in Europe. AIDS/HIV reporting in Europe. Quarterly Report No. 32. Saint-Maurice: European Centre for the Epidemiological Monitoring of AIDS; 1991. 34. CDC Advisory Committee on the Prevention of HIV Infection. External review of CDC’s HIV prevention strategies. Atlanta, Georgia: Centers for Disease Control and Prevention, 1994. 35. Strategic plan for preventing human immunodeficiency virus (HIV) infection. Atlanta, Georgia: Centers for Disease Control and Prevention, 1992. 36. Position statement: Confidential reporting of HIV infection. Atlanta, Georgia: Council of State and Territorial Epidemiologists, 1997. 37. Ward JW, Fleming PL, Buehler JW. Annotation: What will be the role of HIV infection reporting? Am J Public Health 1994;84:1888 – 89. 38. Hogg RS, Weber AE, Craib KJP, et al. One world, on hope: The cost of providing antiretroviral therapy to all nations. AIDS 1998;12:2203–9. 39. Connor EM, Sperling RS, Gelber R, et al. Reduction of maternal–infant transmission of human immunodeficiency virus type 1 with zidovudine treatment. Pediatric AIDS Clinical Trials Group Protocol 076 Study Group. N Engl J Med 1994;331:1173– 80. 40. Mansergh G, Haddix AC, Steketee RW, et al. Cost-effectiveness of short-course zidovudine to prevent perinatal HIV type 1 infection in a sub-Saharan African developing country setting. JAMA 1996;276:139 – 45. 41. Bulterys M, Lepage P. Mother-to-child transmission of HIV. Curr Opin Pediatr 1998;10:143–50. 42. Stimson GV. AIDS and injecting drug use in the United Kingdom, 1987–1993: The policy response and the prevention of the epidemic. Soc Sci Med 1995;41:699 –716. 43. Celentano DD, Nelson KE, Lyles CM, et al. Decreasing incidence of HIV and sexually transmitted diseases in young Thai men: Evidence for success of the HIV/ AIDS control and prevention program. AIDS 1998;12: F29 –36.