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Decline in AIDS Levels Off

By David Brown
THE WASHINGTON POST -- The decline in AIDS deaths in the United States that began years ago has started to level off, and there are disturbing signs that new HIV infections may be rising among young gay men, researchers reported Monday.

While the benefits of powerful antiviral drugs introduced in recent years remain dramatic by any measure, there also is evidence that excessive confidence in them may be prompting some people at risk for HIV infection to practice unsafe sex, researchers said.

The number of AIDS deaths nationwide dropped 42 percent in 1997, but fell only 20 percent in 1998, the researchers reported at the National HIV Prevention Conference in Atlanta, a meeting sponsored by the federal Centers for Disease Control and Prevention. Most of 1998’s reduction occurred in the first three months, with the number of AIDS deaths per month holding relatively steady for the remainder of the year.

A similar trend was seen in the annual decline in new cases of AIDS, which is the advanced stage of infection with HIV, the human immunodeficiency virus. They fell 18 percent in 1997, but only 11 percent in 1998. More recently, epidemiologists in San Francisco determined that one-fifth of all people testing positive for HIV acquired the infection in the previous six months, a sign that spread of the disease continues apace.

The new statistics, following several years of relatively good news about AIDS, offer sobering evidence that the epidemic is far from being under control, experts said.

“The data tell us that this is still an unstable epidemic,” said Helene D. Gayle, director of the CDC’s division of HIV prevention. “No matter what new drugs we have, prevention is ultimately going to be our best weapon.”

The slowing of the decline in AIDS mortality is not unexpected. Life-saving or life-prolonging therapies always have their most dramatic effects, in epidemiological terms, soon after they are widely adopted by previously untreated populations. When many deaths are saved in one year, the pool of untreated people shrinks, reducing the number of lives that can be potentially saved with the treatment in subsequent years.

In the case of antiviral treatment for HIV infection, this began in 1996, the first year that multiple “protease inhibitor” drugs became available in the United States. Today, 85 percent of people with HIV who qualify for the combination therapies are taking them.

Nationally, AIDS deaths dropped from about 50,000 a year in 1995 to 20,000 a year now. In some places, the decline has been breathtaking. In the county that includes Seattle, there were, on average, 435 deaths from AIDS each year from 1993 to 1995. Last year, there were 78. In Seattle, the annual death rate fell from 59 per 100 people with AIDS in 1987 to 4 deaths per 100 people with AIDS in 1998.

Things other than the expected effects of better treatment also can contribute to the flattening of the downward trend in AIDS mortality now being reported. These include the appearance of drug-resistant infection and the inability of some patients to take the medicines, either because of side effects or inconvenience. How much those factors may explain the trend is unknown.

The trend in AIDS mortality, however, doesn’t necessarily reflect the trend in new HIV infections. That’s because of the long lag (on average, about a decade) between the time infection occurs and when the virus has done sufficient damage to the immune system to cause the problems that fit the official definition of AIDS. The new therapies are prolonging the silent period of infection -- indefinitely, it appears, in some cases -- making new AIDS mortality an even less reliable indicator of HIV “incidence,” or rate of new infection.

Recently, however, researchers have used paired AIDS blood tests, one very sensitive and the other relatively insensitive, to distinguish long-standing infections from recent ones. (The new ones give a positive result only on the very sensitive test.) This has provided an unusually good lens with which to study the epidemic among various groups of people at risk.

At the San Francisco Department of Public Health’s HIV counseling and testing sites, 1.1 percent of men reporting homosexual activity were newly infected in the second half of 1997, reported Willi McFarland, a physician and epidemiologist. In the first half of this year, however, 2.8 percent of such men were newly infected, as detected by the paired blood tests.

Although in statistical terms the difference between those two percentages is not significant -- the 2.8 percent could be an upward blip that occurred by chance -- other data suggest a trend may be starting. The rate of rectal gonorrhea in San Francisco -- a powerful predictor of a man’s risk for acquiring HIV -- has gone from 20 cases per 100,000 men in 1994 to 40 cases per 100,000 in 1997. At the same time, the percentage of gay men in the city who report using condoms all the time has fallen from 70 to 60. The percentage of men reporting multiple anal sex partners has risen during that period.

The group with the largest fraction of newly infected people in 1998-99 was gay male users of injected drugs. Incidence of new HIV infection, however, was zero or near zero for other risk groups.