FRIDAY, Oct. 22 (HealthDay News) -- A never-before detected
strain of virus that killed more than one-third of a monkey colony
at a U.S. lab appears to have 'jumped' from the animals to sicken a
human scientist, researchers report.
Although it's an unusual move for that type of virus and does
warrant further monitoring, the researchers stress there is no
cause for alarm at this time. There is no evidence the virus has
spread beyond the single scientist -- who recovered from her
illness -- nor is there even proof that the virus would be
transmissible between humans.
Still, "there is very strong evidence to suggest a cross-species
transmission event happened," said lead investigator Dr. Charles
Chiu, an assistant professor of laboratory medicine and
medicine/infectious diseases at the University of California San
Francisco. "I don't think people should be worried about this right
now. It's more of a worry to public health officials monitoring
these new viruses that have the potential for causing
The study was presented Friday at the Infectious Diseases
Society of America annual meeting in Vancouver, Canada.
The scientist appears to have caught the virus while
investigating an outbreak of illness among a colony of Titi monkeys
at the California National Primate Research Center in Davis, Chiu
Among the monkeys, the virus was highly contagious and deadly:
Of 55 monkeys housed at the center, 23 (about 40 percent) became
seriously ill with upper respiratory symptoms that progressed to
pneumonia and an inflammation of the liver. Nineteen monkeys, or
about 83 percent of those infected, died.
Broad-spectrum antibiotics did not help the monkeys, suggesting
that the pneumonia was caused by the virus and not a secondary
bacterial infection, Chiu said.
Researchers later determined the cause of the illness was an
adenovirus, a broad class of viruses that can cause everything from
relatively harmless respiratory illnesses such as the common cold,
to pneumonia, as well as gastroenteritis, conjunctivitis and
inflammation of the liver in people.
The new strain, however, had never before been identified, Chiu
"This is almost certainly a new species of adenovirus," Chiu said. "By looking at the 'sequence divergence', or how different the genetic sequence of this adenovirus is relatively to other adenoviruses, we believe it is a new species."
The scientist who fell ill had been in close contact with the
monkeys. Though she became seriously ill with pneumonia around the
same time the monkeys were falling ill, she was not hospitalized
and recovered after about four weeks, Chiu said.
Her blood tested positive for antibodies to the virus three
months after the epidemic, Chiu said. While not a definitive test,
Chiu said it's very likely the cause of her illness was the new
Infectious disease and public health experts are always on the
lookout for new viruses that pose a threat to people, said Dr.
Aaron Glatt, a spokesman for the Infectious Diseases Society of
America and president and CEO of St. Joseph Hospital in Bethpage,
While this sort of event makes infectious disease experts sit up
and take notice, "it's not something to be nervous about or worried
about today," Glatt said. "There is not a novel adenovirus
associated with a deadly outbreak in humans, but it's very
interesting from a scientific point of view."
While other viruses can infect more than one species,
adenoviruses tend to be species-specific, which makes this somewhat
unusual, he said. But as of now, there is no evidence of an
outbreak of the virus outside that single monkey colony in Davis,
Chiu and his colleagues are trying to determine the origin of
the virus, including whether it started as a monkey virus or began
in a human and was passed to the monkeys. Since no new monkeys had
been introduced to the colony in six years, one possibility is that
the virus was circulating, undetected, in rhesus monkeys also
housed at the facility and passed somehow to the Titis.
Researchers are also screening several thousand people to
determine if anyone else has antibodies to the virus, which would
indicate prior exposure and that the virus has already been in
circulation in the general human population.
Another question is whether it's contagious among people, Chiu
said. "There is possibly some evidence it's transmissible, but we
just don't know yet," Chiu noted. "If this virus has the potential
for human-to-human transmission, it would have the potential of
developing into an outbreak."
While adenoviruses usually stick to one species, other viruses
do "jump" between species frequently, Chiu said, and a virus that
makes one species very ill may be relatively harmless in
SARS coronavirus, for example, colonizes bats and ferrets
without causing disease, while in humans the illness triggers
severe pneumonia, Chiu said.
Influenza also jumps between species. Pigs may show no signs of
having H1N1 ("Swine flu"), but humans can get very sick from
Researchers are also working to determine if the new adenovirus
is a "recombinant," or combined virus, which includes bits of
genetic information from monkey and human adenoviruses.
"When viruses jump they can cause much more severe disease or less severe disease," Chiu said. "These findings might be an argument to do more broad surveillance of animals. If we can better understand what kind of viruses circulate in animals, it might help predict what viruses might jump over and when."
U.S. Centers for Disease Control and
Prevention has more on adenoviruses.