RATE OF HIV INFECTION FOUND ON DECLINE IN S.F.

Health Officials May Revise Estimates In Light Of 3 Reports

In a rare piece of good news on AIDS, San Francisco health officials
may revise downward their estimates of the number of new HIV
infections each year after three new analyses suggested that the
spread of the virus in the city's gay community has slowed substantially.

Since 2001, the city's highly regarded epidemiology team has held to
an estimate that more than 1,000 city residents are newly infected
with the AIDS virus each year.

But last month, a federal study of HIV among gay men in five U.S.
cities found that new infections in San Francisco were occurring at
about half the rate recorded four years ago.

"This one (CDC) study has been quite an eye opener for us," said Dr.
Willi McFarland, epidemiologist for the San Francisco Department of
Public Health's Office of AIDS.

The study by the national Centers for Disease Control and Prevention
used survey methods considered state of the art in disease
surveillance. Based on a sample of 365 gay men tested in the city,
the study found that men were becoming infected at a rate of 1.2
percent per year.

San Francisco epidemiologists had previously estimated an infection
rate of 2.2 percent.

The startling new finding prompted McFarland's office to analyze
other sets of data often used by the city to track the course of the
epidemic. Two of them -- information collected by the city's Stop
AIDS Project, and surveys of infection rates at city clinics --
pointed to a similar downward trend in new HIV cases.

City officials therefore are expected to convene within a month a
panel of experts to consider lowering San Francisco's official
estimate of annual HIV infections -- which would signal that the
feared second wave of the epidemic detected in 2000 has crested
without a return to the ghastly infection rates of 8.5 percent in the
early 1980s. By 1988, half the city's gay male population was infected.

"HIV incidence among men who have sex with men in San Francisco
appears to be decreasing," said city health director Dr. Mitch Katz.

The reasons for the apparent decline in new HIV infections may take
years to understand, but Katz said the most likely explanation is
that effective AIDS drugs have lowered the level of virus in those
men who are HIV-positive and still having unprotected sex. Another
possibility is that gay men are increasingly reserving the most risky
behaviors, such as anal intercourse without a condom, for partners
who are of the same sero-status -- a practice known as
"sero-sorting." For example, HIV-positive men who sero-sort would
have unprotected sex only with HIV positive partners.

"The message is that, overall, prevention is working," Katz said.

Gauging HIV infection rates is a notoriously difficult task, and
since the beginning of the epidemic, scientists have had to pool data
from multiple sources to make an educated guess. No single study,
such as the CDC survey released last month, will do.

At the forthcoming HIV "consensus conference" in San Francisco,
experts will consider at least 11 different indicators that the city
regularly uses to track the course of the epidemic.

It was such a consensus conference in 2001 that set the city's
estimated HIV rate at 1,048 new infections per year. Prospects now
appear good that the estimate will be substantially reduced.

Even if further analysis confirms a lower infection rate, McFarland
remains cautious.

"The incidence rate is still too high," he said. "There is a lot more
work to be done. It's ground we lost when (HIV) resurged in the first place."

The CDC study, conducted in five major cities, was based on
interviews with more than 1,764 men contacted at bars and dance
clubs, sex clubs and gyms, and on the streets and in parks and shops.
Participants included gay men in San Francisco, Los Angeles, New
York, Miami and Baltimore. In addition to volunteering for blood
tests, they were asked about their partners, where they met them,
their drug usage and other questions.

City health officials were heartened by a finding in the CDC study
that among the five cities surveyed, San Francisco had the lowest
rate of gay men who were infected but didn't know it at the time of the study.

In Baltimore, for example, a startling 40 percent of men
participating in the study tested positive, and 62 percent of them
did not know they were infected when they volunteered to be tested.
In San Francisco, by contrast, 24 percent of participating men tested
positive, and only 23 percent of those did not already know it.

Overall, researchers found that nearly half the men who tested
positive in the survey did not know they were infected -- prompting
calls for increased efforts to encourage people to get the test.

According to McFarland, the city was due for a new consensus
conference anyway, since the last one took place four years ago. Data
from the city's sexually transmitted disease clinics, where infection
rates are expected to be high and were 5.4 percent in 2000, have
fallen to 3.2 percent. At a clinic that provides anonymous testing
services, rates have fallen from 3.9 percent to 2.8 percent.

Surveys by the Stop AIDS Project show a significant trend toward
greater use of sero-sorting, which reduces but does not eliminate the
risk of transmitting or acquiring HIV. Since 2001, the percentage of
HIV-positive men reporting having unprotected sex with HIV-negative
men, or men whose status is unknown, has fallen to 21 percent from 31
percent. The percentage of HIV-negative men who have had unprotected
sex with positive men, or men of unknown sero-status, has fallen to 4
percent from 20 percent.

Stop AIDS spokesman Jason Riggs attributed the apparent decline in
HIV infection rates to efforts that focus prevention messages on men
who are already positive, encouraging behaviors such as sero-sorting.
Programs to discourage use of crystal methamphetamine may also be
paying off in San Francisco, he said.

Studies show that men who use the drug are three to four times more
likely to become HIV-positive. The drug promotes "disinhibition,"
causing users to be more likely to engage in risky sex.

"If we can reduce the numbers of men using and abusing crystal
methamphetamine, we can reduce the number of new infections
significantly," Riggs said.