 HIV (red) attacking a T-cell
Prevention counselors have long called it
the "window period" -- the brief time, lasting
a few weeks or months, between when someone is
infected and when he or she begins to test
positive on HIV-antibody tests. For most of the
last 20 years, this window period has been
viewed as a complicating factor in HIV
prevention counseling, since the results of any
one HIV test cannot be viewed as definitive
proof that an individual is not actually
infected.
More recently, however, researchers have
begun to focus on a far more epidemiologically
significant aspect of the window period. In
part because the body has not yet mounted an
effective antibody reaction to HIV during the
first days and weeks after infection, the virus
replicates rapidly, largely unchecked by the
immune system. Whereas viral loads under 1,000
are generally considered low, and viral loads
above 100,000 are seen as possible reason to
begin antiretroviral treatment, people newly
infected with HIV can have viral loads in the
millions. Thus, during this brief but crucial
period, blood and genital secretions are highly
infectious to others – at the very time that
people are unaware of their infection and have,
by definition, recently engaged in unprotected
sexual or drug using behavior.
For some time, medical science has been
aware of the high viral load found during the
acute phase of HIV infection, as well as the
accompanying flu-like symptoms sometimes called
"seroconversion syndrome." It is only fairly
recently, however, that behavioral scientists
have focused on the public health implications
of acute HIV infection (AHI) and to begin
research into the development of preventive
interventions.
|
"The data are not definitive, but some
studies suggest that as many as 50 percent of
new infections may be traced to people who were
acutely infected and, thus, highly infectious
and probably didn't even know that they were
infected," said HIV Center Investigator
Robert
Remien, who has studied AHI. "So, if as many as
half of new infections in this country now are
occurring during this time period,
interventions could have a very big impact on
transmission."
In all, a strong empirical rationale has
emerged for focusing on the acute period of HIV
infection, and New York and other states are
grappling with questions regarding guidelines
for HIV testing and other policies. For
instance, early detection of new HIV infections
may provide opportunities for immediate
prevention and treatment counseling for the
newly infected individual, as well as quick
contact tracing, partner notification, and
risk-reduction counseling for at-risk partners.
Such prompt intervention, particularly those
that tap into high-risk sexual and drug-using
networks, could help to break the chain of new
infections.
"The clinical advantage of treating people
with acute HIV infection is not yet firmly
established, but it's certainly beneficial to
get people into care early and be able to
follow them closely," noted Dr.
Alan Berkman, a
physician who also studies AHI at the HIV
Center. "We may find out in the next year or
two that there are definite benefits from
starting people with acute infection on
treatment, and that will make it even more
compelling to be able to identify those
individuals."
-- by
Raymond A. Smith |
