By Chris Bowman
A rare virus,
never before known to infect people in North America, has killed
an Alameda County girl and probably two other Californians in
the past 14 months, state health officials announced Thursday.
Tests showed
the girl died of an arenavirus,which is believed to be transmitted
to humans through inhalation of dust carrying the urine, feces
or saliva of infected rodents, officials said.
The arenavirus
is strongly suspected in the June death of a 30-year-old Orange
County woman and in the death one year earlier of a 52-year-old
woman in neighboring Riverside County.
The three
cases were isolated and are not believed to be related, officials
said.
All three
victims complained of flu-like symptoms before being hospitalized
with high fevers, internal bleeding and fluid buildup in their
lungs, the officials said.
Rodent infections
with the arenavirus have been documented in Southern California
in the past few years, but human infections have been observed
only in travelers returning from overseas and in laboratory personnel
accidentally exposed while doing research, said Diana Bonta, the
state health director.
Officials
said the Alameda County girl was on life support for four months
before her death in April. She was 14. The Southern California
women died within a week of their hospitalizations.
Officials
do not believe the disease is communicable; neither members of
the victims' families nor health care workers who treated them
have contracted the virus.
The state
Department of Health Services alerted physicians statewide Thursday
to be on the lookout for similar symptoms and to report to public
health authorities any suspected cases, either pending or past.
"We could
find that it has occurred in the past but was so rare that we
never found it," said MicheleJay, a lead scientist in the
state's investigation.
Investigators
are trying to find out how the victims became infected by the
virus and whether it is treatable. The antiviral agent Ribavirinhas
been successfully used in the tropics for treatment of other arenavirus
infections. Several arenaviruses known to cause mild to severe
infection occur in West Africa and South America.
The best-known
arenavirus is the Lassa strain, a deadly infection that has been
found only in Africa. About 16 percent of its victims die. Even
more deadly is the Machupo virus, which produces Brazilian hemorrhagic
fever and kills 60 percent of victims.
State health
officials believe this is the first discovery of a rodent-carrying
disease in the United States since 1993, when a U.S. strain of
hantavirus was found in the "Four Corners" region of
the Southwest. The outbreak killed at least 26 people. Since then,
191 cases of hantavirus have been diagnosed, according to the
federal Centers for Disease Control.
The arenavirus
strain found in the California deaths is called the Whitewater
Arroyo virus, so named after the place in New Mexico where it
was found in woodratsfour years ago, Jay said.
The discovery
prompted Southern California health officials to begin looking
for the virus. Several of the woodrats they have trapped have
tested positive for antibodies of the virus, Jay said.
Woodrats,
also known as packrats, are found mostly in rural and suburban
areas. They build large nests out of sticks and other debris in
trees and on the ground.
Doctors who
treated the three California victims were exasperated in their
search for a cause and cure, Jay said.
"The
workup on these patients was extensive," she said. "They
were tested for many different bacteria and viruses -- from influenza
all the way to the hantavirus."
Details in
the death of the Riverside County woman led scientists to suspect
a rodent virus, Jay said.
The autopsy
indicated that the woman had bled internally, a tell-tale sign
of an arenavirus at work. In a deathbed interview, she recalled
cleaning up rodent droppings. And that exposure occurred in an
area where vector control workers had found woodrats infected
with the virus.
"Those
are the pieces that came together that made us look for it,"
Jay said
Charles Folhurst,
a scientist at the University of Texas Medical Branchin Galveston
isolated and identified the Whitewater Arroyo virus in a specimen
from the Alameda County patient, Jay said.
The virus
was detected in the bodies of the two other victims through testing
of virus genes, which all but confirms it was the culprit.
Few laboratories
in the United States are equipped to test for the Whitewater Arroyo
virus, Jay said. California health officials are scrambling to
establish the tests, she said.
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