THURSDAY, July 14 (HealthDay News) -- A novel version of a virus
responsible for many well-known illnesses in humans and animals has
managed to jump from one species and spark infection in another,
according to researchers.
This "jumping" virus is from the adenovirus family, responsible
for the common cold, croup, pneumonia and many other illnesses in
humans. Until now -- unlike other types of viruses -- these
particular germs have not been thought capable of cross-species
The finding stems from a high-tech investigation of a 2009
California laboratory outbreak that ravaged a population of New
World titi research monkeys. The never-before-seen virus that
caused a high rate of death among the primates is the same virus
that sickened a lab researcher who had come into direct contact
with the infected animals, the scientists reported.
And once the virus migrated to a human host, it continued its
travels, infecting a member of the researcher's family, who had no
history of exposure to any infected animal.
"Adenoviruses have been thought to be species-specific," said study lead author Dr. Charles Chiu, an assistant professor of laboratory medicine and infectious diseases at the University of California, San Francisco. "That's been the traditional thinking. But we found a novel adenovirus that is unlike any other virus that's been previously described. And it appears to be able to cross species," he added.
"But I definitely don't want to alarm people," said Chiu, who also serves as director of the UCSF Viral Diagnostics and Discovery Center, which led the current investigation. "Yes, this was a very deadly virus among the monkeys -- perhaps the deadliest adenovirus ever seen. But this happened two years ago now, and we haven't seen any evidence at all that this virus or any virus of its kind has continued to spread through the human population."
Chiu and his colleagues reported the case in the July 14 issue
Besides respiratory illnesses, adenoviruses can cause
conjunctivitis, hepatitis, bladder and intestinal infections in
humans, as well as serious -- even deadly -- infections in
The outbreak at the heart of what researchers once viewed as a
viral mystery took place at the California National Primate
Research Center at the University of California, Davis, among a
colony of 65 titi monkeys.
In 2009, over one-third of the primates developed
upper-respiratory symptoms, which soon turned into severe pneumonia
and hepatitis. Despite intensive medical treatment, more than 80
percent of the sick monkeys died.
Researchers named the virus responsible for the outbreak "titi
monkey adenovirus" (TMAdV).
A researcher who was in close contact with the monkeys, who also
developed a severe respiratory illness, remained ill for about a
month with symptoms that included fever, cough and chills. In
addition, two family members developed a similar illness, despite
having had no exposure to the laboratory setting. All three made a
But was the same virus to blame for the severe illnesses in both
the animals and humans? State-of-the-art blood and antibody
analyses suggest that in two of the cases, it was: the researcher
and one family member tested positive for the same adenovirus that
infected the hapless monkeys.
The study authors noted that the virus might have originated
with the monkeys and spread to humans; or it could have taken the
Either way, the research team said that because of the unusually
high fatality rate among the New World primates at the research
center, it is probable that neither humans nor the titi monkeys
served as the original viral "host." If such suspicions hold true,
then the identification of a so-called "patient zero" remains an
Chiu did find antibodies to the novel adenovirus in one healthy
rhesus (Old World) monkey, leading him to suggest that the virus
might have spread from Old World monkeys to the New World colony
that had no antibodies against it.
The importance of getting to the bottom of such lingering
questions led Chiu to suggest that the investigation has so far
only "touched the tip of the iceberg."
"Nature finds a way to introduce a new virus every couple of years," he said. "And this means we have to be alert to viruses and the risk for spreading into the human population."
This is important, Chiu said, "because most of the viruses that
we know cross over from animals to human all the time don't stick.
They don't go anywhere. So if we find that they can cross, and then
acquire the ability to move from human to human, that's a cause for
worry. Because those two factors are what raise the risk for a
pandemic. And this case suggests that perhaps we might want to
track these animal viruses a bit more before they have the chance
to cross over into the human population."
For his part, Dr. Pascal James Imperato, dean of the School of
Public Health at the State University of New York Downstate Medical
Center in New York City, emphasized that while questions about the
case endure, the public should not be unduly alarmed.
"Clearly, this virus was not indigenous to the monkeys who were affected," he noted. "If these monkeys were the normal host for this species they would have accommodated to it, and they wouldn't have died off at this rate. So it was introduced to them. And the question is, from which species was it introduced and how?" Imperato said.
"But on the positive side, I would say that the risk here would appear to be low," he added. "And the reason we can say that is that there were no other reported secondary cases to the primary human case -- at least not in a serious form of the illness -- as far as one can document this. And these two individuals who were infected recovered, which is also positive. So I think the public is not at risk here."
For more on adenoviruses, visit the
U.S. Centers for Disease Control and
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