—EXPERTS CALL IT: One type is “PCR,” the other “b-DNA.” —IT TELLS YOU: How much HIV is in your blood —TAKE
IT: After suspected primary infection. Every three months, before
starting meds. Immediately before you start therapy. About a month
after taking your first cocktail. Every three months on therapy. —RESULTS IN: 4–7 days
M.
Lo Talks: Michelle’s viral load jumped from 1,896 to 3,642 in five
months. “Around that time, I wasn’t feeling my best,” she says. But the
increase was so neglible that it might even be a coincidence.
Viral
load tests measure the amount of HIV in your blood. Except for the
first several months of infection, when the virus and your immune
system are still getting used to each other, here’s the general rule:
The higher the load, the greater the risk to your immune system. Still,
the relationship between viral load and CD4s is
only dimly understood, and this can make treatment decisions tricky.
In 2003, Michelle
had switched from her last regimen in part because of a high viral load,
and that did the trick: She hovered in the four
digits—an OK place for someone with her long treatment history.
MEASURE FOR MEASURE There
are two viral load tests: the more common “polymerase chain reaction”
(PCR) and the “branched DNA” (b-DNA). Just as inches and centimeters
both measure length, these tests come to comparable conclusions. But
results of the two different tests don’t directly correlate. Make sure
you get the same test each time. What is a “normal” viral load for
an HIVer not on meds? That’s hard to say because everyone has a unique
“set point”—a level of virus in the blood that seems to remain constant
over time. Most people now consider anything less than 100,000 virions
per milliliter of blood (PCR) “not high.”
A load in the
millions is not uncommon during seroconversion, when the virus has
plenty of CD4 cells to target and the immune system hasn’t yet revved
up to fight.
HOW LOW CAN YOU GO? If you’re a newbie and lucky enough not to have been infected
with the growing pool of drug-resistant HIV out there, your combo
should bring your viral load down to “undetectable”—that is, below what
the tests can read (one test detects as low as 400; the other as low as
50).
Getting down to 400 may take a month or so on a new
regimen. On average it takes three to four months to reach 50,
depending, of course, on how high your viral load is to start with.
ARE YOU EXPERIENCED? Some
treatment-experienced, med-resistant HIVers (like Michelle) may no
longer be able to reach undetectable. But there’s a growing debate
about how low a viral load needs to be to help halt disease
progression. Getting below 10,000 or even 20,000 or 30,000—partial
viral suppression—has helped raise the absolute CD4 cell count in many
HIVers.
THE BOTTOM LINE Look for your viral load to drop by at
least a power of 100 (from 100,000 to 1,000, for instance) when
starting a regimen. Dropping by less than a power of 10 (e.g., 100,000
to 10,000) is grounds for divorce—and trying a new combo.
