City offers new HIV testing

Procedure detects virus earlier, could identify `hot spots' where it is spread


Battling one of the nation's worst HIV epidemics, Baltimore has joined a growing list of cities to employ a test that detects the virus at an early stage of infection - and could lead authorities to "hot spots" where the virus is being transmitted.

Dr. Joshua Sharfstein, the city's health commissioner, said his department recently made the test available at the city's east- and west-side health clinics. The agency also plans to make it available through community organizations offering HIV testing and counseling.

"It offers patients the opportunity to learn their HIV status earlier in the infection and gives the city the ability to understand where HIV infection is occurring now," Sharfstein said. "That knowledge is the key to intervening and slowing down the spread of this virus."

The move comes slightly more than a year after the Maryland Department of Health and Mental Hygiene began using the test on blood specimens submitted to its lab in Baltimore. That laboratory mainly handles specimens from clinics serving lower-prevalence areas outside the city.

Although the test is valuable to patients seeking early diagnoses, Sharfstein said it might be more valuable in targeting neighborhoods or social networks where the virus is spreading.

In contrast to the older test, which detects antibodies to the AIDS virus that might not emerge until weeks after exposure, the new test looks for genetic evidence of the virus that may be apparent within a week of infection. Specifically, the test scans blood for the genetic code, or RNA, of the virus itself.

This early stage of infection, often called the "window" because it eludes conventional testing, is also a time when patients are highly contagious.

Blood banks have employed RNA tests for years to screen out contaminated donations. Laboratories also use the test to measure the amount of virus - called viral load - circulating in a person's bloodstream.

Viral-load testing is a way to monitor the severity of a person's infection, as well as the progress of treatment.

In 2002, North Carolina became the first state to use RNA tests for individuals who want to know their HIV status. More recently, the cities of Rochester, N.Y., Seattle, San Francisco and Los Angeles have begun using it to varying degrees. Florida and Colorado are planning to do so as well.

Like the other cities and states, Baltimore will use a method aimed at finding people whose infections are a week or two old.

First, the city will test all blood samples for antibodies. People who test positive will be informed and counseled. Presumably, these are people who have been infected for several weeks or more - possibly years.

Specimens that test negative might have no virus whatsoever, but they might also be within the "window" within which antibody testing is ineffective. For that reason, all "negative" samples will be tested for viral RNA.

Patients who emerge as positive using this technique will be presumed to have been infected recently. (To save money, the lab will pool samples in groups of about 60, and will separately evaluate samples within pools that test positive.)

Each year, the city performs about 22,000 tests in its public clinics and mobile van or through community agencies. Of those, about 3 percent - or 660 - test positive, according to Dr. Emily Erbelding, chief of medical services for the Health Department's sexually transmitted disease section.

Last month, the Health Department began using the test on blood samples collected at the west-side Druid Family Health Center at 1515 W. North Ave. and the Eastern Health District, 620 N. Caroline St.

With the new test, the department should be able to diagnose 25 to 30 people a year in the so-called acute stage of infection - people who otherwise would have been missed, she said.

Sharfstein said the public health benefit would be even broader than those numbers indicate, since investigators will be able to counsel not only the patients but also their partners.

So far, the state has identified 12 cases of HIV infection this way, according to Dr. Robert Myers, deputy director of laboratories for the Maryland Department of Health and Mental Hygiene.

Through the end of 2004, Baltimore had the fifth highest incidence of new AIDS cases in the United States, and accounted for half of all people with HIV/AIDS in Maryland.

Dr. Peter Leone, medical director for North Carolina's HIV prevention and care program, said RNA testing helped to identify a pattern of risk-taking behavior at college campuses statewide.

Initially, testing turned up two students on a college campus who were recently infected. Interviews with the students brought health investigators to a network of bars and Web sites where students were meeting - leading to high-risk sex.

"By identifying behaviors, you can begin to understand what is currently leading to acquisition of HIV and begin to intervene," said Leone, who is also an associate professor of medicine at the University of North Carolina.

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