Cover; HIV: 20 Years of Research; Exclusive Online Issues; by Staff Editor; 1 Page(s)

Table of Contents; HIV: 20 Years of Research; Exclusive Online Issues; by Staff Editor; 1 Page(s)

AIDS and the Use of Injected Drugs; HIV: 20 Years of Research; Exclusive Online Issues; by Don C. Des Jarlais and Samuel R. Friedman; 5 Page(s)

The tiny blood transfusions that take place when drug users share needles or syringes serve to transmit disease efficiently. Nothing has illustrated this fact more tragically than the rapid spread of HIV, the human immunodeficiency virus and the causative agent of AIDS. More than 50 countries have documented HIV infection among persons who inject illicit drugs. An additional 30 countries have reported the practice of illegal drug injection; as a result, these places have populations at high risk of contracting or transmitting the AIDS virus. Once HIV is established among such a group, it moves into the community at large through sexual contact and pregnancy.

No hard figures exist for the number of these drug users throughout the world; the best estimate is about five million people. There are, however, hard figures for the impact of AIDS on this group in the U.S.: more than one third of all AIDS cases, or about 113,000, are associated with the injection of illicit substances. Even in the absence of definitive numbers, the proliferation of HIV among these users has clearly become a medical catastrophe internationally as well. The most conservative predictions by public health institutions foresee increased use of illegal drugs via injection in many countries and increased transmission of HIV among people who take drugs in this way.

How HIV Defeats the Immune System; HIV: 20 Years of Research; Exclusive Online Issues; by Martin A. Nowak and Andrew J. McMichael; 7 Page(s)

The interplay between the human immunodeficiency virus (HIV) and the immune system turns out to be significantly more dynamic than most scientists would have suspected. Recent research indicates that HIV replicates prodigiously and destroys many cells of the immune system each day. But this growth is met, usually for many years, by a vigorous defensive response that blocks the virus from multiplying out of control. Commonly, however, the balance of power eventually shifts so that HIV gains the upper hand and causes the severe immune impairment that defines fullblown AIDS.

We have put forward an evolutionary hypothesis that can explain the ultimate escape of the virus from immune control, the typically long delay between infection and the onset of AIDS, and the fact that the extent of this delay can vary considerably from patient to patient. Most infected individuals advance to AIDS over the course of 10 years or so, but some patients are diagnosed within two years of infection, and others avoid AIDS for 15 years or more.

The African AIDS Epidemic; HIV: 20 Years of Research; Exclusive Online Issues; by John C. Caldwell and Pat Caldwell; 6 Page(s)

AIDS has swept across sub-Saharan Africa on an extraordinary scale. Two thirds of the roughly 16 million people in the world infected with the human immunodeficiency virus (HIV), which causes AIDS, live there. Half of the world's cases are found in what we call the AIDS belt--a chain of countries in eastern and southern Africa that is home to only 2 percent of the global population.

Heterosexual intercourse serves as the main vehicle for spreading HIV throughout sub-Saharan Africa. This is in stark contrast to the developed world, where the virus is most frequently transmitted during homosexual intercourse or when intravenous drug users share contaminated syringes. Attempts to halt the flood of AIDS cases in Africa will not succeed until researchers can determine what factors contribute to the remarkable prevalence of the disease among heterosexuals. Such a diagnosis will also help us figure out how likely it is that heterosexual epidemics might extend into Asia or the West.

In Search of AIDS-Resistance Genes; HIV: 20 Years of Research; Exclusive Online Issues; by Stephen J. O'Brien and Michael Dean; 8 Page(s)

Most people today are all too familiar with the devastating effects of HIV, the human immunodeficiency virus. The virus, which is transmitted by blood-toblood contact, may produce no symptoms for years. But typically within 10 to 15 years it destroys key cells of the immune system and causes AIDS (acquired immunodeficiency syndrome). Loss of immunity enables microorganisms that would normally be kept in check to proliferate uncontrollably and can allow life-threatening cancers to develop. So far in the U.S. alone, AIDS has killed more than 350,000 people and has become the principal cause of death among those 24 to 44 years old. Another 750,000 Americans harbor the virus, part of some 30 million who are affected worldwide.

In the past few years, advances in drug therapy have enabled a number of patients to cheat death. Sophisticated combinations of medicines have diminished the levels of virus in the body and restored immune function. Those feats have been justifiably well publicized, but findings less known to the public have also caused a stir of late in the AIDS research community.

Improving HIV Therapy; HIV: 20 Years of Research; Exclusive Online Issues; by John G. Bartlett and Richard D. Moore, sidebars by Douglas R. Richman, John W. Mellors; 10 Page(s)

A vaccine would certainly be ideal for preventing infection by HIV and thus for avoiding AIDS--the late stage of HIV infection, when immunity is severely impaired. Yet the near-term prospects for a vaccine are poor, and people who contract the virus need care. For the immediate future, then, many scientists are concentrating on improving therapy.

Until only a few years ago, HIV infection was everyone's worst nightmare--it was almost invariably a progressive, lethal disease that completely robbed its victims of dignity. Most medical interventions focused on treating pneumonias and other serious "opportunistic" infections that stemmed from immune failure, not on controlling HIV itself.

Hope in a Vial; HIV: 20 Years of Research; Exclusive Online Issues; by Carol Ezzell; 6 Page(s)

It wasn't supposed to be this hard. When HIV, the virus responsible for AIDS, was first identified in 1984, Margaret M. Heckler, then secretary of the U.S. Department of Health and Human Services, predicted that a vaccine to protect against the scourge would be available within two years. Would that it had been so straightforward.

Roughly 20 years into the pandemic, 40 million people on the planet are infected with HIV, and three million died from it last year (20,000 in North America). Although several potential AIDS vaccines are in clinical tests, so far none has lived up to its early promise. Time and again researchers have obtained tantalizing preliminary results only to run up against a brick wall later. As recently as two years ago, AIDS researchers were saying privately that they doubted whether even a partially protective vaccine would be available in their lifetime.