6
billion
Pounds of
BPA produced
globally in 2003
93
percent
Americans
with detectable
BPA levels
Pathogen fingered as a potential
culprit in chronic fatigue syndrome
Little-known retrovirus found in many people with condition
By Nathan Seppa
The long, fruitless search for the cause
of chronic fatigue syndrome has taken
a curious turn. An obscure retrovirus
shows up in two-thirds of people diagnosed with the condition and can infect
human immune cells, scientists report
online October 8 in Science.
These findings don’t establish that
the pathogen, called gammaretrovirus
XMRV, causes chronic fatigue, cautions
study coauthor Robert Silverman of the
Cleveland Clinic’s Lerner Research Institute. “Nevertheless, it’s exciting because
it is a viable candidate for a cause.”
Roughly 1 million to 4 million people
in the United States have chronic fatigue
syndrome, according to the Centers for
Disease Control and Prevention. Characterized by unexplained mental and
physical exhaustion, memory lapses,
muscle pain, insomnia, digestive distress and other health problems, chronic
fatigue is often diagnosed only after
everything else has been ruled out.
In the study, researchers tested blood
from 101 people diagnosed with the syndrome and found that 68 were infected
with the retrovirus. An analysis of blood
from 218 healthy people showed that only
eight had XMRV — nearly 4 percent.
“This is a very striking association —
two-thirds of the patients,” says John
Coffin of Tufts University in Boston, who
wasn’t involved in the study.
Studies of its genes suggest XMRV
arose from a mouse retrovirus that
somehow jumped to humans.
Study coauthor Judy Mikovits, a cell
biologist at the Whittemore Peterson
Institute in Reno, Nev., says that the
retroviral infection could result in an
immune deficiency that leads to chronic
fatigue symptoms in some people. Other
retroviruses, such as HIV, are known to
attack the immune system. In this study,
researchers showed that XMRV could
infect immune cells in the blood.
“This may end the controversy as to whether there
is an underlying infection in
some cases of chronic fatigue
syndrome but is unlikely to
explain all cases,” says Dedra
Buchwald of the University of
Washington in Seattle. Retroviruses can awaken latent
viruses already in cells, so
XMRV might affect health only indirectly,
by activating other viruses, she says.
XMRV, short for xenotropic murine
leukemia virus–related virus, also shows
up in some men with prostate cancer,
particularly those with aggressive malig-
nancies, another research team reported
in September in the Proceedings of the
National Academy of Sciences.
In the new study, the researchers found
hints that the retrovirus is transmitted
by blood. But it’s probably not spreading
very fast, Mikovits says.
Further research is under way to fine-
tune testing for XMRV, and more stud-
ies are planned to clarify its
occurrence rate in the gen-
eral population. Mikovits
and her colleagues are
also investigating already-
approved antiretroviral
drugs to see if these will ben-
efit people diagnosed with
chronic fatigue.
A nearly 4 percent infec-
tion rate in healthy controls means that
as many as 10 million Americans may har-
bor a hidden infection, Coffin notes. But
until further studies are done, the effects
of those infections remain unclear.
“It’s exciting
because [the
retrovirus]
is a viable
candidate for
a cause.”
ROBERT SILVERMAN
Reviewing H1N1
flu’s worst cases
Antivirals, ventilators help, but
fatalities show lungs hit hard
and death. In severe cases, inflammation
in the lungs leads to fluid buildup in air-
ways and lung tissues, says the University
of Toronto’s Robert Fowler, a coauthor on
t wo of the studies. “Most patients are still
able to take breaths, but these breaths are
ineffective,” he says.
In the largest of the studies, scientists in
Canada monitored 168 patients deemed
critically ill with H1N1 flu. Patients averaged only 32 years of age and received
intensive treatment, but 17 percent died.
Doctors in Australia and New Zealand
identified 68 critically ill patients with
a median age of 34 for the second study.
The fatality rate was 21 percent. In the
third study, a team examined records of
58 critically ill patients in Mexico with a
median age of 44, and found a fatality rate
of 41 percent.
In Canada and Mexico, most patients
received mechanical ventilation, and in
all three regions many were also given the
drug Tamiflu, with apparent benefit.
By Nathan Seppa
Lung inflammation and respiratory failure are largely responsible for the fatal
cases of H1N1 swine flu, three new studies
show. The findings confirm observations
that H1N1 hits young adults hardest but
can be fought off, in many cases, with the
use of antiviral flu drugs and a mechanical
ventilator that aids breathing.
Conducted between late March and
late August, the studies, reported online
October 12 in the Journal of the American
Medical Association, find that the most
critically ill patients suffer from oxygen
deprivation in the blood, a dangerous condition that can lead to shock, organ failure
