Download Bats, camels and emerging viral disease by Dr. David L. (“Woody

Bats, camels and emerging viral disease
by Dr. David L. (“Woody”) Woodland
(as published in the Summit Daily News of October 1, 2013)
Many of you may recall the spring of 2003 when the world held its breath as a new and deadly
virus called SARS emerged. The virus, so named because it caused Severe Acute Respiratory
Distress Syndrome, or SARS, had spread from the Far East to countries around the globe with
alarming speed. A particular virus hotspot was Toronto, Canada, where 251 cases were
reported with 43 deaths. Fortunately, the virus was limited in its ability to spread from person to
person, and careful hygiene and quarantine procedures were able to stop it in its tracks. When
the outbreak ended in 2004, most of the world had dodged a bullet, though one that did kill 774
people.
The SARS outbreak tested global health authorities. Although their response was not perfect,
their ability to identify the virus, determine appropriate containment and recommend treatment
options was a stunning success. It also served as a practice run for future outbreaks from new
pathogens that may prove to be more problematic than the SARS coronavirus ultimately turned
out to be.
Today, the world faces a new threat sure to test global response networks. The so-called MERS
(Middle Eastern Respiratory syndrome) virus is a new human pathogen beginning to spread
from its Middle Eastern origin. Like the SARS virus, the MERS virus also infects the respiratory
tract and can cause severe acute pneumonia and renal failure, often with a fatal outcome. Most
cases have occurred in Saudi Arabia, Jordan, Qatar and the United Arab Emirates, but infection
has also been imported by sick travelers to Tunisia, the United Kingdom, Italy, Germany and
France. To date, there are 130 laboratory-confirmed cases of infection with MERS; 58 patients
have died.
You may be wondering where these new deadly pathogens originate? In most cases, it is
apparent that newly emerging viruses have their origins in other animal species. Typically, a
virus that is well adapted to its host species and is not particularly lethal will learn to infect a new
(in this case human) host, often with very lethal consequences. In the case of SARS, the virus
was found to be a resident of bats that had probably learned how to infect humans through an
intermediary host. Other classic examples of animal viruses triggering new infections in humans
include the AIDS virus (derived from chimpanzees and gorillas), Ebola virus (derived from fruit
bats) and influenza (derived from aquatic birds).
But what about MERS? The virus is so new that scientists are still in the early stages of
identifying its animal origins. However, recent studies have indicated that viral genetic material
isolated from the feces of an Egyptian tomb bat was identical to the genetic sequence of the
virus present in a Saudi Arabian MERS victim. While promising, the sequence tested was too
short to allow a definitive identification. In addition, although researchers felt that bats may be
the primary source of the virus, there are too few bat-human encounters to explain the
frequency of observed cases, possibly implicating an intermediate host. The answer to this
puzzle may be the camel. Researchers have now found that the blood from some Middle
Eastern camels contains antibodies specific for the MERS virus. Although no virus was found in
the animals tested, the antibodies indicate that the animal had made an immune response to an
earlier encounter with the virus. In other words, it is beginning to look as if bats are infecting
camels with MERS and that the sick camels are then infecting humans. Camels make sense as
an intermediary host since they have considerable contact with humans in the Middle East –
camel farms are common and camel racing is a popular sport. Further research will be
necessary to nail down the transmission patterns of the MERS virus.
In the meantime, considerable efforts are underway by many national and international
organizations to contain the MERS outbreak. Foremost in this effort is the Global Outbreak Alert
and Response Network, a collaboration of more than 150 organizations, networks and
institutions involved in the rapid identification, confirmation and response to outbreaks of new
infectious diseases. The primary approach consists of rapid reporting and the implementation of
specific infection prevention and control mechanisms in healthcare facilities providing care for
suspected MERS patients. There is every confidence that this latest threat to global health will
be contained.
I’ll be talking more about MERS and other emerging viruses at a free community forum on
Wednesday, October 2 at 7 PM at the Silverthorne Town Pavilion. I look forward to seeing you
there.
David L. “Woody” Woodland, Ph.D. is the Chief Scientific Officer of Silverthorne-based Keystone
Symposia on Molecular and Cellular Biology, a nonprofit dedicated to accelerating life science discovery
by convening internationally renowned research conferences in Summit County and worldwide. Woody
can be reached at 970-262-1230 ext. 131 or [email protected].
To view more (Petri) Dish articles, please visit “News” on the Keystone Symposia website.