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Trends in Hiv Prevalence Essay ABSTRACT HIV prevalence in the world is becoming increasingly high. As of mid-1998, the HIV/AIDS pandemic continues to spread unequally around the world. In many cities in sub-Saharan African countries more than a quarter of young and middle-aged adults are infected with HIV, whereas in most developed countries, the number of annual AIDS cases continues to decrease. The status and of HIV epidemics in most other areas of the world remains uncertain because of inadequate data on the prevalence of HIV-risk behaviours. Hence, this paper presentation seeks to examine the trends of HIV prevalence across the world taking all the continents into consideration. INTRODUCTION HIV Human Immunodeficiency Virus is a lentivirus, and like all viruses of this type, it attacks the immune system. Lentiviruses are in turn part of a larger group of viruses known as retroviruses. The name lentivirus literally means slow virus because they take such a long time to produce any adverse effects in the body. They have been found in a number of different animals, including cats, sheep, horses and cattle. However, the most interesting lentivirus in terms of the investigation into the origins of HIV is the Simian Immunodeficiency Virus (SIV) that affects monkeys, which is believed to be at least 32,000 years old. It is now generally accepted that HIV is a descendant of a Simian Immunodeficiency Virus because certain strains of SIVs bear a very close resemblance to HIV-1 and HIV-2, the two types of HIV. HIV-2 for example corresponds to SIVsm, a strain of the Simian Immunodeficiency Virus found in the sooty mangabey (also known as the White-collared monkey), which is indigenous to western Africa. The more virulent, pandemic strain of HIV, namely HIV-1, was until recently more difficult to place. Until 1999, the closest counterpart that had been identified was SIVcpz, the SIV found in chimpanzees. However, this virus still had certain significant differences from HIV There are a number of factors that may have contributed to the sudden spread of HIV, most of which occurred in the latter half of the twentieth century and these includes: * Blood Transfusion * Drug Use * Mother-to-Child Transfusion ORIGIN OF HIV The origin of AIDS and HIV has puzzled scientists ever since the illness first came to light in the early 1980s. For over twenty years it has been the subject of fierce debate and the cause of countless arguments, with everything from a promiscuous flight attendant to a suspect vaccine programme being blamed. The first recognized case of AIDS occurred in the USA in the early 1980s. A number of gay men in New York and California suddenly began to develop rare opportunistic infections and cancers that seemed stubbornly resistant to any treatment. At this time, AIDS did not yet have a name, but it quickly became obvious that all the men were suffering from a common syndrome. The discovery of HIV, the Human Immunodeficiency Virus, was made soon after. While some were initially resistant to acknowledge the connection (and indeed some remain so today), there is now clear evidence to prove that HIV causes AIDS. So, in order to find the source of AIDS, it is necessary to look for the origin of HIV, and find out how, when and where HIV first began to cause disease in humans. In February 1999 a group of researchers from the University of Alabama announced that they had found a type of SIVcpz that was almost identical to HIV-1. This particular strain was identified in a frozen sample taken from a captive member of the sub-group of chimpanzees known as Pan Troglodytes (P. t. troglodytes), which were once common in west-central Africa. The researchers (led by Paul Sharp of Nottingham University and Beatrice Hahn of the University of Alabama) made the discovery during the course of a 10-year long study into the origins of the virus. They claimed that this sample proved that chimpanzees were the source of HIV-1, and that the virus had at some point crossed species from chimps to humans. Their final findings were published two years later in Nature magazine. In this article, they concluded that wild chimps had been infected simultaneously with two different simian immunodeficiency viruses which had viral sex to form a third virus that could be passed on to other chimps and, more significantly, was capable of infecting humans and causing AIDS. These two different viruses were traced back to a SIV that infected red-capped mangabeys and one found in greater spot-nosed monkeys. They believe that the hybridisation took place inside chimps that had become infected with both strains of SIV after they hunted and killed the two smaller species of monkey. They also concluded that all three groups of HIV-1 namely Group M, N and O (see our strains and subtypes page for more information on these) came from the SIV found in P. t. troglodytes, and that each group represented a separate crossover event from chimps to humans. It has been known for a long time that certain viruses can pass between species. Indeed, the very fact that chimpanzees obtained SIV from two other species of primate shows just how easily this crossover can occur. As animals ourselves, we are just as susceptible. When a viral transfer between animals and humans takes place, it is known as zoonosis. The most commonly accepted theory on how zoonosis took place, and how SIV became HIV in humans is that of the hunter. In this scenario, SIVcpz was transferred to humans as a result of chimps being killed and eaten or their blood getting into cuts or wounds on the hunter. Normally the hunters body would have fought off SIV, but on a few occasions it adapted itself within its new human host and became HIV-1. The fact that there were several different early strains of HIV, each with a slightly different genetic make-up (the most common of which was HIV-1 group M), would support this theory: every time it passed from a chimpanzee to a man, it would have developed in a slightly different way within his body, and thus produced a slightly different strain. An article published in The Lancet in 20044 , also shows how retroviral transfer from primates to hunters is still occurring even today. In a sample of 1099 individuals in Cameroon, they discovered ten (1%) were infected with SFV (Simian Foamy Virus), an illness which, like SIV, was previously thought only to infect primates. All these infections were believed to have been acquired through the butchering and consumption of monkey and ape meat. Discoveries such as this have led to calls for an outright ban on bush meat hunting to prevent simian viruses being passed to humans. Others theories include: * The oral polio vaccine (OPV) theory * The contaminated needle theory * The colonialism theory * The conspiracy theory Four of the earliest known instances of HIV infection are as follows: * A plasma sample taken in 1959 from an adult male living in what is now the Democratic Republic of the Congo. * A lymph node sample taken in 1960 from an adult female, also from the Democratic Republic of the Congo. * HIV found in tissue samples from an American teenager who died in St. Louis in 1969. A 1998 analysis of the plasma sample from 1959 suggested that HIV-1 was introduced into humans around the 1940s or the early 1950s.   In January 2000, the results of a new study16 suggested that the first case of HIV-1 infection occurred around 1931 in West Africa. This estimate (which had a 15 year margin of error) was based on a complex computer model of HIVs evolution. However, a study in 200817 dated the origin of HIV to between 1884 and 1924, much earlier than previous estimates. The researchers compared the viral sequence from 1959 (the oldest known HIV-1 specimen) to the newly discovered sequence from 1960. They found a significant genetic difference between them, demonstrating diversification of HIV-1 occurred long before the AIDS pandemic was recognised. The authors suggest a long history of the virus in Africa and call Kinshasa the â€Å"epicentre of the HIV/AIDS pandemic† in Central Africa. They propose the early spread of HIV was concurrent with the development of colonial cities, in which crowding of people increased opportunities for HIV transmission. If accurate, these findings imply that HIV existed before many scenarios (such as the OPV and conspiracy theories) suggest. Until recently, the origins of the HIV-2 virus had remained relatively unexplored. HIV-2 is thought to come from the SIV in Sooty Mangabeys rather than chimpanzees, but the crossover to humans is believed to have happened in a similar way (i.e. through the butchering and consumption of monkey meat). It is far rarer, significantly less infectious and progresses more slowly to AIDS than HIV-1. As a result, it infects far fewer people, and is mainly confined to a few countries in West Africa. In May 2003, a group of Belgian researchers published a report18 in Proceedings of the National Academy of Science. By analysing samples of the two different subtypes of HIV-2 (A and B) taken from infected individuals and SIV samples taken from sooty mangabeys, Dr Vandamme concluded that subtype A had passed into humans around 1940 and subtype B in 1945 (plus or minus 16 years or so). Her team of researchers also discovered that the virus had originated in Guinea-Bissau and that its spread was most likely precipitated by the independence war that took place in the country between 1963 and 1974 (Guinea-Bissau is a former Portuguese colony). Her theory was backed up by the fact that the first European cases of HIV-2 were discovered among Portuguese veterans of the war, many of whom had received blood transfusions or unsterile injections following injury, or had possibly had relationships with local women. TRENDS IN HIV PREVALENCE Since 2001, MEASURE Demographic and Health Surveys (DHS) have included HIV testing in 31 countries. In 13 of these countries testing has been included in two surveys, which provides an opportunity to examine trends. However, trend data must be viewed with caution, as only some changes are statistically significant. Trends in HIV Prevalence In the charts below, changes in HIV prevalence that are statistically significant are marked with an asterisk and a star.   While it may appear that HIV prevalence has decreased in most countries, these decreases are only statistically significant in the Dominican Republic, Burkina Faso, Cameroon, Tanzania, Malawi, and Zimbabwe. This means that in these countries, the change is large enough that it is unlikely that the decrease is due to chance alone; it probably represents true change in the HIV prevalence in the population. In some countries, such as Tanzania, the decrease is statistically significant for the population as a whole, and for men, but not for women. In Cameroon, Burkina Faso, and Zimbabwe, HIV prevalence has decreased among both women and men. DHS surveys have not detected any change in HIV prevalence in Mali, Senegal, Ethiopia, Kenya, Rwanda, Lesotho, or Zambia. What does this mean? Because HIV prevalence is a measure of all HIV infections in a population, a decrease in HIV prevalence could indicate that fewer people are becoming infected, and/or that more people with HIV have died in a population. Similarly, an increase in HIV prevalence could point to more new infections, and/or could indicate an increase in HIV-positive individuals living longer on anti-retroviral therapy. TRENDS IN HIV PREVALENCE IN ASIA PACIFIC REGION With over 60 percent if the worlds population, the Asia-Pacific Region presents a wide diversity of HIV-related risk environments, in terms of behavioural, political and cultural factors. Within the framework of this diversity, there has also been a wide range of HIV epidemics and responses, both across and within countries. It is not therefore possible to present a simple analysis of the actual and potential occurrence of HIV infection in this vast region. Our understanding of the HIV epidemic and its determinants in the Asia-Pacific Region has improved substantially over the past 3-5 years, as a number of countries have implemented comprehensive surveillance systems for HIV prevalence, and sexual and injecting risk behaviours. Despite these advances, a number of countries still have a limited capacity to assess the occurrence of HIV infection and related behaviours, and to monitor the impact of interventions. A recent factor of importance in the Asia-Pacific environment has been the economic tumult of the past year. While various predictions have been made of the potential impact on the HIV epidemic, it is not possible to state with any certainty whether their net effect will be to increase or decrease the incidence of risk behaviour or HIV transmission. Since extensive HIV transmission has been a very recent phenomenon in a number of Asia-Pacific countries, there has so far been little experience with the care and support of people with HIV-related illness. Apart from Australia, Thailand and Japan, few countries have a healthcare workforce, which is adequately prepared to care for substantial numbers of people developing HIV-related illness. Without simplifying too much, it is possible to classify the differing patterns of HIV transmission into broad categories, based on available surveillance data. In Australia and New Zealand, the virtually all HIV transmission has been through sex between men, and the incidence of transmission via this route has long been recognized as having declined substantially in the 1980s. In a few countries, such as Thailand, Cambodia and parts of Myanmar and India, heterosexual transmission has been extensive, mediated through large-scale sex industries but extending now to the regular partners of sex workers male clients. Some countries have HIV epidemics among injecting drug users (IDU) with limited associated heterosexual transmission. These include countries such as Thailand, Malaysia, Vietnam, and some areas of India and China. Other countries have limited, but well documented spread of HIV infections, such as the Philippines, Indonesia, Japan, and South Korea. Several countries have not reported substantial numbers of HIV infection, but do not appear to have comprehensive, ongoing surveillance systems. Papua New Guinea, Pakistan and Bangladesh are countries which may have a substantial risk environment, and need to strengthen their surveillance activities. 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. These include large metropolitan areas in western and southern India (Mumbai, Chinnai); 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 out.