http://www.promedmail.org/pls/otn/f..._BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,79527
Archive Number 20091006.3469
Published Date 06-OCT-2009
Subject PRO/AH> Ebola & Marburg hemorrhagic fever, Egyptian fruit bat - W. Africa
EBOLA AND MARBURG HEMORRHAGIC FEVER, EGYPTIAN FRUIT BAT - WEST AFRICA
*********************************************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>
Date: Fri 2 Oct 2009
Source: Bloomberg.com [edited]
<http://www.bloomberg.com/apps/news?pid=20601124&sid=aCDY59ymDHII>
Virus Hunters Find Ebola, Marburg Source in Fruit Bat
-----------------------------------------------------
Scientists are closing in on the source of Ebola and Marburg
[hemorrhagic fevers], 2 of the world's most-lethal infectious
diseases. After a 5-year search in the jungles of Africa, an
international team of virus hunters has identified a fruit bat that
may be the natural host for both hemorrhage-causing diseases. Also,
these viruses are more widespread than previously thought, according
to their research, which will be published via an open-access BioMed
Central journal.
The study, based on blood tests on more than 2000 bats in Gabon and
the Republic of Congo, will help scientists solve a mystery that has
confounded them for more than 30 years: which species harbor Ebola
and Marburg [viruses] without getting sick. The answer may explain
how the viruses persist in the environment and point to ways humans
can avoid a disease that causes fatal bleeding and organ failure in
at least half of cases.
"Very eminent scientists have been searching for decades to find the
source," said John Mackenzie, a Melbourne-based virologist who
assists the World Health Organization in its response to outbreaks.
"Until you know what it is, you can't piece together the epidemiology
or begin to think about managing the risks to both humans and wildlife."
Marburg hemorrhagic fever was recognized in 1967, when outbreaks
occurred in laboratories in Marburg and Frankfurt, Germany, and in
the Serbian [Yugoslavian] capital, Belgrade. Cases were traced to
African green monkeys imported for research and polio vaccine
production. Then, 9 years later, a closely related virus was found to
have sparked a deadly outbreak near the Ebola River in the Democratic
Republic of Congo, formerly known as Zaire.
Disease trackers have tested everything from snakes to guinea pigs in
the search for an animal reservoir and have been repeatedly led back
to caves, mines and bats. A 2005 study published in the journal
Nature found evidence of symptomless ebolavirus infection in 3
species of fruit bat in West Africa, indicating that these animals
may be the ones silently harboring the virus. In March [2009],
scientists reported the 1st evidence directly connecting a human
Ebola hemorrhagic fever outbreak to the putative fruit bat reservoir.
The study reported this week is the 1st to show that ebolavirus and
marburgvirus are circulating simultaneously in bat populations in one
country. While several human Ebola hemorrhagic fever outbreaks have
occurred in Gabon, no cases of Marburg hemorrhagic fever have been
reported there, the authors said. The presence of marburgvirus in the
West African nation represents a "potential and previously
unrecognized threat to humans," they said.
"These findings provide much stronger evidence for a reservoir in
bats," Xavier Pourrut, a virologist at Gabon's International Center
for Medical Research in Franceville and the study's lead author, said
in a telephone interview. "The next step is to understand how the
viruses circulate in bat populations over time." Pourrut and
collaborators from the Special Pathogens Branch of the Centers for
Disease Control and Prevention in Atlanta and France's Institute for
Development Research looked for evidence of previous ebolavirus and
marburgvirus infection in the blood samples of 2147 bats from at
least 9 species. Tests were conducted from 2003 to 2008 in 3 regions
of Gabon and in the Ebola epidemic region of north Congo.
Of all the bats sampled in significant numbers, only specimens of the
cave-roosting Egyptian fruit bat, or _Rousettus aegyptiacus_, were
found to harbor antibodies against both ebolavirus and marburgvirus,
the authors wrote, "suggesting that this species may be a natural
host of both viruses." The Egyptian rousette, with a doglike face and
ears, is found along the Nile River in Egypt, across Sub-Saharan
Africa, eastern Mediterranean and the Middle East. While some groups
may occasionally roost outside in trees, the bats of this species
prefer to inhabit caves, mines and tombs, and feast on fruit trees at
night. These preferences give it a stronger link with the circulation
of ebolavirus and marburgvirus more frequently found in rain forests,
said Pierre Formenty, leader of the emerging and dangerous pathogens
team at the World Health Organization (WHO) in Geneva.
Formenty was among 29 authors of a study published in July [2009]
that showed Marburg virus could be isolated from seemingly healthy
Egyptian fruit bats caught in Uganda's Kitaka Cave, where miners
infected with the virus in 2007 had worked. While some outbreaks in
humans have been directly linked to contact with bats, more evidence
exists to link cases with infected apes, chimpanzees and other
primates that are often consumed in Central Africa. These animals, in
turn, probably got the virus by eating fruit contaminated with saliva
or other bodily fluids from bats, according to Pourrut.
Once a human is infected, there is no cure for ebolavirus or
marburgvirus infection. After an incubation period of about a week,
victims rapidly develop high fever, diarrhea, vomiting, respiratory
disorders and hemorrhaging. Death can ensue within a few days. About
a quarter of Marburg hemorrhagic fever cases are fatal, whereas case
fatality rates range from 50 to 80 percent with Ebola hemorrhagic
fever in Africa.
Ebolavirus may circulate naturally within at least one other bat
species and spread to members of the Egyptian rousette via contact
with infected saliva left on fruit remnants, Formenty said in an
interview. Also, no link with the Egyptian fruit bat was found with
at least 3 Ebola hemorrhagic fever outbreaks, he said. "We've got a
whole lot of clues on the crossword puzzle and we're just filling the
blanks now," said Bob Swanepoel, a virologist at South Africa's
National Institute for Communicable Diseases in Johannesburg, who 1st
sought to unravel the history of Marburg hemorrhagic fever in the
mid-1970s. Scientists will complete the task within a decade, he said.
[Byline: Jason Gale]
--
Communicated by:
ProMED-mail Rapporteur Mary Marshall.
[This report describes evidence linking for the 1st time both the
Ebola and Marburg hemorrhagic fevers with viruses present in fruit
bats, and one bat in particular -- the Egyptian fruit bat, _Rousettus
aegyptiacus_. (An image of an Egyptian fruit bat can be viewed via
the above URL for the news agency article.) The evidence for virus
infection of these bats is based on serological analysis and it is
unclear from this report whether infectious virus has been isolate
from these animals. Publication of the data is awaited with interest.
It is suggested that direct transmission of ebolavirus and
marburgvirus to humans from these bats may be rare and that humans
are more likely to be exposed to infection through contact with
infected primates, hunted as a source of food.
- Mod.CP]
[The interactive HealthMap/ProMED map for Africa is available at:
<http://healthmap.org/r/0035>
- CopyEd.EJP]
[see also:
Ebola hemorrhagic fever, fruit bat - Congo DR, 2007 20090530.2014
2007
----
Marburgvirus, fruit bats - W. Africa 20070823.2755]
....................cp/ejp/dk
Archive Number 20091006.3469
Published Date 06-OCT-2009
Subject PRO/AH> Ebola & Marburg hemorrhagic fever, Egyptian fruit bat - W. Africa
EBOLA AND MARBURG HEMORRHAGIC FEVER, EGYPTIAN FRUIT BAT - WEST AFRICA
*********************************************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>
Date: Fri 2 Oct 2009
Source: Bloomberg.com [edited]
<http://www.bloomberg.com/apps/news?pid=20601124&sid=aCDY59ymDHII>
Virus Hunters Find Ebola, Marburg Source in Fruit Bat
-----------------------------------------------------
Scientists are closing in on the source of Ebola and Marburg
[hemorrhagic fevers], 2 of the world's most-lethal infectious
diseases. After a 5-year search in the jungles of Africa, an
international team of virus hunters has identified a fruit bat that
may be the natural host for both hemorrhage-causing diseases. Also,
these viruses are more widespread than previously thought, according
to their research, which will be published via an open-access BioMed
Central journal.
The study, based on blood tests on more than 2000 bats in Gabon and
the Republic of Congo, will help scientists solve a mystery that has
confounded them for more than 30 years: which species harbor Ebola
and Marburg [viruses] without getting sick. The answer may explain
how the viruses persist in the environment and point to ways humans
can avoid a disease that causes fatal bleeding and organ failure in
at least half of cases.
"Very eminent scientists have been searching for decades to find the
source," said John Mackenzie, a Melbourne-based virologist who
assists the World Health Organization in its response to outbreaks.
"Until you know what it is, you can't piece together the epidemiology
or begin to think about managing the risks to both humans and wildlife."
Marburg hemorrhagic fever was recognized in 1967, when outbreaks
occurred in laboratories in Marburg and Frankfurt, Germany, and in
the Serbian [Yugoslavian] capital, Belgrade. Cases were traced to
African green monkeys imported for research and polio vaccine
production. Then, 9 years later, a closely related virus was found to
have sparked a deadly outbreak near the Ebola River in the Democratic
Republic of Congo, formerly known as Zaire.
Disease trackers have tested everything from snakes to guinea pigs in
the search for an animal reservoir and have been repeatedly led back
to caves, mines and bats. A 2005 study published in the journal
Nature found evidence of symptomless ebolavirus infection in 3
species of fruit bat in West Africa, indicating that these animals
may be the ones silently harboring the virus. In March [2009],
scientists reported the 1st evidence directly connecting a human
Ebola hemorrhagic fever outbreak to the putative fruit bat reservoir.
The study reported this week is the 1st to show that ebolavirus and
marburgvirus are circulating simultaneously in bat populations in one
country. While several human Ebola hemorrhagic fever outbreaks have
occurred in Gabon, no cases of Marburg hemorrhagic fever have been
reported there, the authors said. The presence of marburgvirus in the
West African nation represents a "potential and previously
unrecognized threat to humans," they said.
"These findings provide much stronger evidence for a reservoir in
bats," Xavier Pourrut, a virologist at Gabon's International Center
for Medical Research in Franceville and the study's lead author, said
in a telephone interview. "The next step is to understand how the
viruses circulate in bat populations over time." Pourrut and
collaborators from the Special Pathogens Branch of the Centers for
Disease Control and Prevention in Atlanta and France's Institute for
Development Research looked for evidence of previous ebolavirus and
marburgvirus infection in the blood samples of 2147 bats from at
least 9 species. Tests were conducted from 2003 to 2008 in 3 regions
of Gabon and in the Ebola epidemic region of north Congo.
Of all the bats sampled in significant numbers, only specimens of the
cave-roosting Egyptian fruit bat, or _Rousettus aegyptiacus_, were
found to harbor antibodies against both ebolavirus and marburgvirus,
the authors wrote, "suggesting that this species may be a natural
host of both viruses." The Egyptian rousette, with a doglike face and
ears, is found along the Nile River in Egypt, across Sub-Saharan
Africa, eastern Mediterranean and the Middle East. While some groups
may occasionally roost outside in trees, the bats of this species
prefer to inhabit caves, mines and tombs, and feast on fruit trees at
night. These preferences give it a stronger link with the circulation
of ebolavirus and marburgvirus more frequently found in rain forests,
said Pierre Formenty, leader of the emerging and dangerous pathogens
team at the World Health Organization (WHO) in Geneva.
Formenty was among 29 authors of a study published in July [2009]
that showed Marburg virus could be isolated from seemingly healthy
Egyptian fruit bats caught in Uganda's Kitaka Cave, where miners
infected with the virus in 2007 had worked. While some outbreaks in
humans have been directly linked to contact with bats, more evidence
exists to link cases with infected apes, chimpanzees and other
primates that are often consumed in Central Africa. These animals, in
turn, probably got the virus by eating fruit contaminated with saliva
or other bodily fluids from bats, according to Pourrut.
Once a human is infected, there is no cure for ebolavirus or
marburgvirus infection. After an incubation period of about a week,
victims rapidly develop high fever, diarrhea, vomiting, respiratory
disorders and hemorrhaging. Death can ensue within a few days. About
a quarter of Marburg hemorrhagic fever cases are fatal, whereas case
fatality rates range from 50 to 80 percent with Ebola hemorrhagic
fever in Africa.
Ebolavirus may circulate naturally within at least one other bat
species and spread to members of the Egyptian rousette via contact
with infected saliva left on fruit remnants, Formenty said in an
interview. Also, no link with the Egyptian fruit bat was found with
at least 3 Ebola hemorrhagic fever outbreaks, he said. "We've got a
whole lot of clues on the crossword puzzle and we're just filling the
blanks now," said Bob Swanepoel, a virologist at South Africa's
National Institute for Communicable Diseases in Johannesburg, who 1st
sought to unravel the history of Marburg hemorrhagic fever in the
mid-1970s. Scientists will complete the task within a decade, he said.
[Byline: Jason Gale]
--
Communicated by:
ProMED-mail Rapporteur Mary Marshall.
[This report describes evidence linking for the 1st time both the
Ebola and Marburg hemorrhagic fevers with viruses present in fruit
bats, and one bat in particular -- the Egyptian fruit bat, _Rousettus
aegyptiacus_. (An image of an Egyptian fruit bat can be viewed via
the above URL for the news agency article.) The evidence for virus
infection of these bats is based on serological analysis and it is
unclear from this report whether infectious virus has been isolate
from these animals. Publication of the data is awaited with interest.
It is suggested that direct transmission of ebolavirus and
marburgvirus to humans from these bats may be rare and that humans
are more likely to be exposed to infection through contact with
infected primates, hunted as a source of food.
- Mod.CP]
[The interactive HealthMap/ProMED map for Africa is available at:
<http://healthmap.org/r/0035>
- CopyEd.EJP]
[see also:
Ebola hemorrhagic fever, fruit bat - Congo DR, 2007 20090530.2014
2007
----
Marburgvirus, fruit bats - W. Africa 20070823.2755]
....................cp/ejp/dk