Monday will mark 25 years since the first AIDS cases were reported in the United States, and despite millions of dollars' worth of research by the world's top scientists, no effective vaccine has been found against the virus that causes the deadly disease.
More than 1 million Americans are living with the AIDS virus, and an estimated 40,000 new infections are expected in the United States this year, say scientists with the federal Centers for Disease Control and Prevention (CDC) -- and there may never be a vaccine.
"There is need for a vaccine," Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said yesterday in an interview. "But this virus has the uncanny ability to evade the body's immune system ... and the immune system can't seem to make a response to eliminate the microbe. And no one has solved this very difficult scientific issue."
Dr. Fauci said "it would be folly" to try to predict when a vaccine to prevent HIV might be available.
An analysis of the first quarter-century of AIDS and the human immunodeficiency virus (HIV) that causes it, published today in the CDC's Morbidity and Mortality Weekly Report (MMWR), shows a mix of prevention successes and failures.
The contagious disease first attracted the attention of top U.S. medical officials June 5, 1981, when an MMWR article described cases of what eventually became known as acquired immune deficiency syndrome (AIDS) among five young homosexual men in the Los Angeles area.
Since then, AIDS has "become one of the greatest public challenges both nationally and globally," having killed more than 22 million people worldwide and more than 500,000 in the United States, CDC epidemiologists wrote in the current MMWR.
"At this milestone marking the 25th year of AIDS, one way to recognize those persons who have died, and those who have been affected by this epidemic, is to accelerate the development of measures for preventing HIV transmission," the CDC scientists wrote.
New combination drug therapies that became widely available in the 1990s now allow infected patients to live longer, but "HIV/AIDS remains a potentially deadly chronic disease," the authors said.
Because the first U.S. cases of the disease were concentrated among homosexual men, scientists initially called it Gay-Related Immune Deficiency, or GRID. But in 1982, it was renamed AIDS, as the condition claimed victims in other populations that included injection-drug users who shared dirty needles, babies born to infected mothers, hemophiliacs and blood-transfusion recipients who received tainted blood or blood products.
Sexual contact and dirty hypodermic needles are still the most common modes of transmitting the AIDS virus.
The first diagnoses of AIDS involved young white homosexual men, but the disease has since spread to take a heavy toll among women and minorities. The most recent federal statistics show that more than half of new HIV diagnoses in the United States are among blacks, who constitute 13 percent of the U.S. population.
Heterosexual transmission -- which accounted for about 6 percent of AIDS cases in 1987 -- now accounts for 30 percent of HIV/AIDS diagnoses. Women are especially vulnerable to becoming infected during sexual intercourse; in 2002, HIV infection was the leading cause of death for U.S. black women ages 25 to 34, the CDC reported.
Children of infected mothers are also at risk for AIDS. Transmission can occur during pregnancy, labor, delivery or breastfeeding. In the early years of the AIDS plague, approximately 30 percent of babies born to HIV-infected mothers became infected, but that transmission rate is now less than 2 percent.
"The reduction in perinatal [mother-to-child] transmission of HIV has probably been our biggest success to date," said Karen Hunter, a CDC spokeswoman.
Less success has been shown in dealing with HIV transmission among homosexual men.
"Men who have sex with other men account for approximately 45 percent of newly reported HIV/AIDS diagnoses, and nearly 54 percent of cumulative AIDS diagnoses," the MMWR report said.