Geneva,
SWITZERLAND (6/29/98)- Two new forms of HIV testing should help identify
infected individuals more easily and inexpensively, a key in worldwide
AIDS prevention efforts, reported researchers at the 12th World AIDS Conference.
A new HIV testing technology developed by the Centers for Disease Control
and Prevention offers a simple way to identify recently infected individuals
using a single blood sample. Previous HIV antibody tests have not allowed
researchers and health care practitioners to easily distinguish between
newly infected individuals and those who have been infected for longer
periods of time.
The new technique provides a practical method for directly measuring
the number of new HIV infections in specific communities. Until now,
efforts to estimate HIV incidence utilized mathematical models based on
the occurrence of AIDS (which may not reflect recent shifts in the path
of the epidemic) or long term studies which follow a group of individuals
over time (which are difficult, expensive and do not reflect incidence
beyond the group being studied).
The CDC testing strategy was created by altering the sensitivity of
an existing HIV antibody test. Researchers modified the test to make
it less sensitive to HIV antibodies. By using the modified test in
conjunction with another highly sensitive antibody test, researchers can
identify people with recent infection who have not
yet developed a full antibody response.
"The ability to detect recent infections has profound implications for
both HIV prevention and treatment. If we know where and among whom new
infections are occurring, we can better direct and evaluate HIV prevention
programs. Moreover, new therapies are most effective if initiated
early in infection. By knowing the status of an individual's disease,
health care providers can more effectively treat HIV," said the CDC's Robert
S. Janssen, M.D., in an interview.
The researchers tested the new approach on two very different populations
-- gay men with high HIV incidence in a long-term study in San Francisco
and repeat blood donors where incidence is extremely low. The new method
accurately determined HIV incidence among blood donors and found that the
incidence in this population was extremely low (7.18 per 100,000 per year)
and did not change statistically significantly between 1993 and 1996.
"These data suggest that HIV has not spread widely among the population
overall, but these data tell us nothing yet about trends in high-risk populations
such as minority women, gay and bisexual men and injection drug users,"
Janssen says. "We've demonstrated that the technique can work and
can tell us a great deal about where
the epidemic is going. The next step is to apply the technology
more widely and use it to evaluate and direct services to populations at
greatest risk."
FIRST HIV URINE TEST
Researchers at New York University School of Medicine have developed
the first complete urine test system for measuring HIV-1. The test has
been approved by the US Food and Drug Administration, and is expected to
broaden the acceptance and availability of HIV testing worldwide.
Urine testing offers several important advantages compared to blood-based
HIV tests. These include: greater safety and ease of use for health-care
workers; lower cost of sample collection; and stronger consumer acceptance.
"The new test is extremely useful and should expand the reach of HIV
testing," says the lead inventor, Alvin Friedman-Kien, M.D., Professor
of Dermatology and Microbiology at NYU. "Most people don't want to have
their blood drawn, but anybody will give you a urine specimen. And in developing
countries, where they don't have the personnel and the sterile needles
and syringes for drawing blood or the equipment to test it, a urine test
will be a real boon."
The new urine test requires only commonly available technologies and
instrumentation. Since HIV is not spread through urine, the new test eliminates
the risk of infection to health-care workers through accidental exposures.
Another advantage of the new test is its simplicity. The patient need only
provide a urine sample, which requires no preservation and can remain stable
for 55 days at room temperature.
"It's important that people get tested," says Dr. Friedman-Kien.
"First, we know that triple therapy started early delays and may even prevent
the onset of HIV disease. Second, people who are made aware that they are
infectious may not spread the disease as rapidly to other people. In addition,
increased testing will tell us more about the epidemiology of HIV. The
true incidence of this disease is not thoroughly known or understood."
The new HIV urine test could have an even larger impact abroad. According
to the World Health Organization and UNAIDS, 30 million people worldwide
are infected with HIV, yet only 10 percent know their HIV status. This
should change with the availability of the urine test, which will cost
only about one-tenth as much as HIV blood tests because of savings in the
collection, storage, and disposal of samples.
"This could be one of our greatest tools in helping to confine the AIDS
epidemic -- especially in places like China, India and southeast Asia,
which have some of the fastest growing populations of HIV-infected people
in the world. From a public health management perspective, these nations
don't yet have even basic information on how and where AIDS is impacting
their peoples. The urine test system will provide them with a cost-effective,
practical way to get that vital data," said Dr. Friedman-Kien
"In my opinion, the urine HIV testing system is highly reliable and
readily accepted by the patients. We can collect and transport urine samples
from the field to the laboratory very safely, because unlike blood, the
urine of HIV-infected people contains only HIV antibody, not the infectious
virus itself. Another potential use of this test," Professor Montagnier
adds, "would be to use it for urine antibody monitoring, which should allow
for better follow-up of patients and volunteers in future clinical trials
of treatments and vaccines," said French researcher Professor Luc
Montagnier, codiscoverer of HIV.
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