Epidemics-Philippines

http://www.fhi.org/

1. Introduction

The World Health Organization (WHO) Regional Office for the Western Pacific in Manila, Philippines, graciously hosted the first Monitoring the AIDS Pandemic (MAP) Network symposium, The Status and Trends of the HIV/AIDS/STD Epidemics in Asia and the Pacific, on 21-23 October 1997, which was an official satellite symposium of the 4th International Congress on AIDS in Asia and the Pacific.

The three-day MAP Network symposium held in Manila was the first symposium formally organized by this new global network formed in December 1996 by the AIDS Control and Prevention (AIDSCAP) Project of Family Health International, the François-Xavier Bagnoud Center for Health and Human Rights of the Harvard School of Public Health and the Joint United Nations Programme on HIV/AIDS (UNAIDS). It was the third in a continuing series of regional and global symposia that have been organized to understand the trajectory of the HIV/AIDS pandemic. Starting with the Status and Trends of the HIV/AIDS Epidemics in Africa Symposium that was held in Kampala, Uganda, in December 1995, a team of internationally recognized technical specialists in epidemiology, modeling, economics, demography, public health and international development was formed to monitor the dynamics of the HIV/AIDS pandemic and various regional epidemics. By collecting, analyzing and disseminating information on HIV/AIDS, this team of experts, which has grown rapidly over the course of two years into a global network, seeks to assist governments, organizations and the world at large to respond more actively and effectively to the challenges posed by the HIV/AIDS pandemic.

The MAP symposium in Manila brought together 40 global and regional experts, including MAP members and some specially invited participants, to achieve the following objectives:

·         To present and share information on the status and trends of the HIV/AIDS/STD epidemics in Asia and the Pacific and analyze this information in a global context;

·         To review the epidemiological and behavioral patterns among the HIV/AIDS/STD epidemics affecting the different populations in the region;

·         To identify specific data needs for monitoring and forecasting the HIV/AIDS/STD epidemics in the region; and

·         To produce and disseminate a consensus report on the current status of the HIV/AIDS/STD epidemics in Asia and on the current and projected trends for these epidemics in the region.

Because a large percentage of the world's population resides in the Asia-Pacific region, the symposium held in Manila was important in enabling MAP to focus strategically on the evolving HIV/AIDS and sexually transmitted disease (STD) epidemics in the Asian and Pacific countries, fuse current knowledge, identify gaps therein and determine topical and geographical areas for action.

The symposium began by first reviewing the global HIV/AIDS/STD situation to position the various Asia-Pacific epidemics within the worldwide context. From then on, the team concentrated on the situation in the overall region and the Western Pacific and Southeast Asian subregions, presented country-specific epidemic profiles on Australia, China, India, Japan, Malaysia, Myanmar, Philippines, and Vietnam and discussed past, present and potential future issues of relevance.

This provisional report, coauthored by the MAP Manila Symposium participants and produced in some 24 hours, reflects a consensus of the analysis, determinations, projections and recommendations brought forward during the symposium. Its aim is to provide information that can be used by international as well as local bodies to briefly review the most important aspects of the history of the HIV/AIDS epidemics in the Asia-Pacific region to date, recognize the current status of and trends within these epidemics, and take immediate action to affect the course of these epidemics in the future.

2. The Status and Trends of the HIV/AIDS/STD Epidemics in Asia and the Pacific

With a population in excess of 2.5 billion -- representing more than sixty percent of the world's population -- the Asia-Pacific region has the potential to influence greatly the course and overall impact of the global HIV/AIDS pandemic. This report examines the status and trends of HIV infection and AIDS in countries of Asia and the Pacific, a region which, for the purpose of this analysis, stretches from and includes India on the west, to Japan and island nations in the Pacific, and from China in the north, to countries forming Oceania in the south.

Epidemic patterns

The spread of HIV in this region began in the early to mid-1980s. Early infections could be traced to sexual contacts with infected persons residing outside the region, as well as some apparent further spread within the region itself. By the late 1980s, however, it had 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 injecting drug use (IDU).

By early 1997, South and South East Asia accounted for an estimated 5.2 million (23 percent) of the 22.6 million adults and children living with HIV in the world. About one-third of adults living with HIV in the region are female. As the HIV epidemic is still relatively recent, HIV disease, including AIDS, is only beginning to emerge and the associated needs for care are rising steeply. The estimated HIV prevalence in 15 to 49 year-old populations varies from zero (DPR Korea) to one per several thousand in most countries in the region, up to 2 to 3 percent in Cambodia, Myanmar and Thailand.

Figure 3. HIV Trends in Asia and the Pacific - 1997
 

HIV epidemics in Asia and the Pacific are diverse, localized and have different trends over time (see Figure 1). Against this backdrop, however, it is becoming increasingly clear that the intensity of HIV epidemics associated with sex work, affecting both female sex workers and their clients, is primarily determined by the daily or weekly number of sex partners (clients) per sex worker, the frequency of use of commercial sex by men, and such other factors as the rate of regular condom use in commercial sex and the magnitude and quality of the response to the epidemics. Epidemics associated with injecting drug use have, in many situations, led to explosive outbreaks in the IDU population and then to their sexual partners (e.g., in the late 1980s in Thailand; Myanmar; the Yunnan province of China; and the Manipur state of India, Vietnam and Malaysia). The prevalence of HIV infection in IDUs in these areas reached staggering levels with prevalence reaching 50 to 90 percent within a few months.

Although HIV can spread rapidly among IDUs who share contaminated injection equipment, and then from them to their sexual partners, these epidemics have so far resulted only in limited spread of HIV to the heterosexual population at large. It may be assumed that for a variety of reasons including social isolation of some IDU populations and their sexual partners from other communities, and/or stigmatization to which they are subjected, there are only tenuous bridges between them and other sexually active adults. Strikingly, in Asia and the Pacific, HIV epidemics associated with commercial sex and those involving IDUs do not appear to fuel each other significantly. These epidemics appear to emerge and evolve almost independently from each other, as exemplified by the two concurrent HIV epidemics in Thailand, which were caused by two different subtypes of HIV, with minimum cross-over.

From a regional perspective, the magnitude and short-term trends of HIV epidemics are largely dependent on the extent of ongoing epidemics in a few countries: Cambodia, India, Thailand, Myanmar and, because of their population size, Indonesia and China. With a population close to 1 billion and multiple epidemic foci, India projects the image of a complex epidemic, involving focal outbreaks among injecting drug users and extensive HIV spread among female sex workers and their clients in several regions.

Of increasing concern in the region is the issue of blood safety and HIV transmission. In 1995, WHO/GPA estimated that less than 50 percent of blood transfusions in the region were being routinely screened for HIV. Currently in Bangladesh, virtually no screening for HIV antibodies is performed in the nearly 200,000 units of blood transfused annually. In India and Myanmar, screening of donor blood for HIV remains far from complete and measures are being taken through improved donor selection to address this issue.

Mapping the epidemics

If the HIV epidemics were analyzed on a country-by-country basis, as if HIV epidemics respected national geopolitical boundaries, most countries in the Asian-Pacific region project the reassuring image of low prevalence (proportion of adults living with HIV/AIDS) and low incidence (proportion of adults newly infected each year). Such is the case of Australia and New Zealand which, early in the epidemic, experienced sudden epidemics in men having sex with men (MSM) with a peak of incidence in the mid-1980s, followed by a rapid decline. The spread among IDUs in these two countries has been and remains limited (less than 2 percent), and heterosexual transmission remains at low levels (the prevalence of HIV among pregnant women is lower than 1 per 10,000).

Such is the case as well for Japan, where an initial dramatic outbreak of HIV infection among people with haemophilia was brought under control in the mid-1980s (see Box 1), and where other modes of transmission are only contributing minimally to a limited HIV burden in the country (less than 1 HIV-infected person per 10,000 adults in 1997). Also reassuring would be the situation in China where, in spite of increasing trends in HIV incidence in IDUs in selected southern provinces (Yunnan, Guanxi), the overall national rate of HIV prevalence in adults in this large country remains below 4/10,000 -- one tenth to one-fifth the prevalence found in Western Europe and in North America, and the spread of HIV from IDUs to their sexual partners accounts for most of the heterosexually acquired HIV infections.

Less reassuring would be the estimated and projected trends in India. There, a sharp increase in the estimated number of HIV infections from a few thousand in the early 1990s to a cumulative minimum of 2.5 million in 1997, in a context of a severe gap of knowledge about prevailing risk-taking sexual behaviors, creates great uncertainty about the future course and impact of the epidemics. Yet, the 1997 national prevalence of HIV infection in adults may be between 0.2 to 0.5 percent which, on first analysis, would not place India high on the world list of "hardest hit" countries where prevalence rates may range from 10 to 25 percent.

HIV prevalence among sex workers in India varies widely from state to state, with high HIV prevalence in western and southern India to low levels of HIV in eastern and northern India. HIV prevalence among sex workers tested in Mumbai (formerly Bombay) rose from 1 to 51 percent between 1987 and 1993. Prevalence among sex workers in Calcutta was consistently low at about one percent until 1994, but there are indications that it might be rising. In Mumbai, HIV prevalence increased from two to three percent in STD clinic attendees before 1990 to 36 percent in 1994. Among antenatal clinic attendees tested in Mumbai, two percent tested positive for HIV in 1995 and around 5 percent in 1996. In Manipur, rates of HIV infection among the antenatal clinic attendees are rising.

In some countries, HIV prevalence has remained very low (less than 0.1 percent in the 15- to 49-year-old population. In the Philippines, AIDS case reporting has slowly increased to a total of 958 reported as of September 1997. HIV surveillance has found only a few cases of HIV infection among female sex workers, male STD clinic patients and men who have sex with men. Similarly, a small number of AIDS cases and low levels of HIV infection have been reported from Indonesia.

When examined through the lens of current national HIV prevalence and incidence rates, most other countries in Asia and the Pacific would conform to a pattern of low prevalence and slow HIV spread (see Figure 2).

Large-scale epidemics ahead?

Are HIV epidemics likely to expand abruptly in India, or in other countries in Asia and the Pacific? To answer this question, possible clues can be drawn from past history in several countries, including Thailand, Myanmar and Cambodia. In Thailand, information was available on IDU needle sharing practices and sex work in the country when, in the mid-1980s, HIV had not begun to spread in epidemic form. The epidemics that were predicted but insufficiently prevented did occur later in this decade, infecting an estimated 800,000 women, men and newborns by 1997. Prevalence rates in pregnant women reached 2 to 3 percent in 1995 nationwide, while rates in army recruits rose to around 4 percent in 1993, then levelled off and began to decline. In Myanmar, rates of HIV infection in IDUs, sex workers and pregnant women are similar to those found in Thailand. Consistent with an East-West gradient of HIV prevalence in Myanmar, the epicenter of the epidemics appears to lie east of the country. The analysis of geographical differentials in HIV infection rates and trends over time underscores both the deepening severity of the epidemics and the potential for national, aggregate data to mask important sub-national epidemic trends. In Cambodia, HIV spread rapidly in the early 1990s, reaching high levels in sex workers (about 40 percent HIV prevalence) and from 2 to 3 percent of the 15- to 49-year-old population (see Box 2). The evolution of the epidemic in Cambodia country illustrates the potential for HIV to spread rapidly and widely when patterns of commercial sex involve high mobility, a high sexual partner exchange rate and low condom use.

Empirical evidence thus exists showing that sudden and sharp increases in HIV incidence can and have occurred in Asia. However, the lack of quantitative and qualitative epidemiological, behavioral and social information on the nature of and linkages between sexual networks in any of these countries rules out any reliable prediction of the future course of HIV epidemics in countries that would intuitively appear vulnerable to rapid spread. These countries include, in particular, Malaysia, Nepal and Vietnam, where rapid increases of HIV incidence in various vulnerable populations are being noted. There is an urgent need to collect and analyze systematically the information needed for the dual purpose of projecting epidemic trends and targeting prevention toward factors that seem to influence the vulnerability of the population to the further -- and possibly rapid -- spread of HIV.

Populations of affinity

The analysis of HIV epidemic trends in the region becomes more meaningful when a focus is placed on populations whose cultural and social affinity and networks transcend geopolitical borders. A new geography of HIV/AIDS in the region then emerges that helps recognize the foci of intense HIV spread. (See the map, Figure 3.) These include large metropolitan areas in western and southern India (Mumbai, Tamilnadu) (see Box 3); the India/Nepal border area; the larger "Golden Triangle," which reaches out to Northern Thailand, eastern Myanmar, but also encompasses the areas of Manipur in India and Yunnan in China; and the Mekong delta area, which includes Cambodia and southern Vietnam. To gain better understanding of the dynamics of HIV epidemics, factors of affinity between populations as well as mobility patterns must be explored and mapped.

The potential for continued spread of HIV/AIDS in Asia and the Pacific is real and requires determined and sustained prevention efforts. Several countries have already experienced intense HIV epidemics in certain population groups or, in some cases, in the population at large. In these countries, including India, Thailand, Myanmar and Cambodia, the individual impact of HIV has begun to be felt as AIDS has imposed new demands on the health care systems. It is essential that countries reinforce their prevention and care efforts in order to enhance their response to the existing HIV/AIDS challenge. In addition, countries should make every effort to collect and analyze the information needed to assess and monitor the evolving potential for large-scale HIV epidemics.

Recognizing the threat of emerging or fast-growing epidemics in certain populations is essential to an early and effective response. Acknowledging the possibility that, in other populations, rapid and extensive spread of HIV may not occur is equally crucial as policy and decision makers may, on the basis of this information, orient efforts and resources towards people who are most at risk.

Figure 1. HIV Penetration into Asian and the Pacific Countries

Figure 2. HIV Distribution Among Selected Asian And Pacific Populations

3. Risk and vulnerability

There are three factors that appear to play a crucial role in HIV transmission in the Asia and Pacific region: female sex work, substance use and mobility. Female sex workers and their clients have been a major factor in the heterosexual transmission of HIV in Thailand, Cambodia and parts of India and Myanmar. Separate but explosive epidemics have been seen in some IDU populations in Thailand, Myanmar, Manipur (India), and Malaysia. And mobile populations, particularly at national borders, are at higher risk of HIV acquisition due to the fact of being away from home and community, and the anonymity and loneliness of traveling. The following three sections focus on monitoring the HIV epidemics in these vulnerable populations.

3.1 Female Sex Work in the Asia-Pacific Region

The numbers of commercial sex workers

Female sex workers operate in all countries in the region, but it is important to know how large the sex-worker population may be to adequately interpret surveillance results. It is believed that in some countries, rapid increases in the number of sex workers have resulted from significant political, social or economic changes.

The number of female sex workers in countries can range from a few thousand to a few hundred thousand. Thailand, for example, has approximately 80,000 to 100,000 female sex workers -- an estimate that only recently has gained consensus. In most countries, however, validated estimates of the numbers of sex workers are almost non-existent. Without such numbers, interpretation of surveillance results, policy commitment, planning, intervention designing, and resource allocation are extremely difficult (see Box 4).

All estimates need regular updating and validation but these two approaches are worthy of replication in other settings. Neither method can work without the trust and involvement of sex workers themselves.

Diversity

The nature of sex work and the profile of sex workers vary enormously within and between countries. There are female and male sex workers, and those that work full-time, part-time or seasonally. Sex workers may operate in a variety of settings such as brothels, bars, massage parlors, street corners, restaurants, etc. Sex workers operating in government-registered establishments exist in a few countries such as the Philippines, in contrast to the freelance sex workers in most countries of this region. There are also commercial sex areas that are highly organized, such as in Indonesia, as opposed to those with bonded or sex workers imprisoned in underground settings. There are women in brothels who cannot refuse sex with customers and those in massage parlours or bars who have more freedom of decision.

For surveillance purposes, sex work can be characterized by work conditions, methods of recruitment, number of clients per week, price, how clients are contacted, where sex takes place, types of clients, existence of employers or agents. Despite these diversities, some types of sex workers are more visible and/or more easily brought to the attention of government or public health officials. These are usually the sex workers who are the subjects of epidemiological studies presented without acknowledging the fact that they represent only a subset of all sex workers. Without a clear understanding of these diversities, effective surveillance cannot be designed or implemented.

Sex workers and HIV

Frequency of exposure to HIV infection through sexual intercourse is the key factor for transmission of HIV among sex workers. In many countries, a significant proportion of sex workers is infected with HIV. The rates might vary from less than 1 percent to 40 percent or higher in some settings (see Table 1).

Even where HIV infection has not yet spread extensively, STD infection is often very high among sex workers. For example, in one brothel area in Bangladesh, 95 percent of 466 sex workers tested positive to antibodies for genital herpes virus and 60 percent for syphilis, although HIV was not detected among any of them. With the progression of the epidemic, HIV tends to increase where other STDs are present.

HIV, STD, and behavioral surveillance

Systematic, continuous and quality sentinel surveillance of HIV and STD will provide not only the indications of an emerging epidemic but its progress over time as well. This will benefit policy formulation, planning and resource allocation. For sex workers, confidentiality, community participation and protection against stigmatization should be integral components of surveillance activities. STD services should also be provided as part of the surveillance package. However, if serosurveillance is to be used for monitoring success of intervention programs, it must be accompanied with behavioral surveillance (see Section 4.2) because HIV prevalence may not decline for several years despite successful interventions. Behavioral surveillance results can also be used to direct the detailed design of prevention activities with special emphasis on specific sub-groups within sex worker populations.

Table 1. HIV prevalence among various sex worker populations in Asia