Posted on 10/07/2009 2:57:55 PM PDT by James Oscar
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 ProMED-mail is a program of the International Society for Infectious Diseases
Date: Fri 2 Oct 2009 Source: Bloomberg.com [edited]
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]
GENETIC ANALYSIS OF THE OUTBREAKS
Investigations into the outbreaks of Ebola in humans during the late 1990's pointed to a link with great apes.
The origins of many of these epidemics could be traced to direct human contact with dead chimpanzees or gorillas, either through hunting bush meat or from handling carcasses found in the forest.
The index [first] cases were mainly hunters and transmission occurred by direct person-to-person contact.
We have identified at least 10 separate chains of transmission, each originating from one index case occurring between October 2001 and May 2003.
By analyzing the genetic material of the virus to see whether these outbreaks had resulted from multiple introductions of a single viral strain or separate introductions of several strains of Ebola it was discovered that:
(1) There were at least eight different strains of Ebola involved, showing that for this relatively short period under study the mode of transmission of the disease was more complex than previously imagined.
(2) Because Ebola is a genetically stable virus - unlike say influenza, which mutates rapidly - the fact that many strains are involved suggested that there have been multiple independent introductions of the virus from the reservoir species into apes and humans.
Different strains of Ebola virus may be widespread throughout the forests of central Africa, with simultaneous infection of great apes occurring from unknown natural hosts under particular but unknown environmental conditions.
Ebola outbreaks probably do not occur as a single outbreak spreading throughout the Congo basin as others have proposed but are due to multiple episodic infection of great apes.
THE UKNOWN RESERVOIR
The great unknown, of course, is the name of this reservoir species.
We aren't near to identifying the animal but we have some ideas, in particular fruit bats.
We don't have much evidence at all, just observations and ideas.
Both apes and fruit bats eat the same kind of food so it is not unreasonable to assume that they may come into close contact with one another at certain times of the year. Ebola outbreaks in wild animals seem to occur at the beginning of the dry season. But no one has yet shown that it is possible to find Ebola virus in wild bats.
In South Africa a scientist succeeded in infecting fruit bats experimentally and he observed rapid development of the virus.
So although it is technically possible to infect fruits bats with Ebola, there is still no evidence that this is the mystery reservoir species.
Until this animal is found, the sole measure that we can take in predicting and preventing an Ebola outbreak in humans is to watch what is happening to gorillas and chimpanzees in the wild.
I wish there were better news.
57 posted on Monday, April 26, 2004 8:05:52 PM by Mother Abigail
http://www.freerepublic.com/focus/chat/865868/posts?q=1&;page=51#57
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What concerns me most is that we might begin to see an infection pattern with Ebola that is now well documented in Marburg outbreaks.
1. We know that human infection with Ebola comes about through the intermediary of infected great ape carcasses.
2. The viral transmission to primates occurs in the dry season, a period when food resources become increasingly scarce. The great apes then come into competition with bat species for fruit supplies when foraging and can be infected notably by blood or by placental fluid that escapes when bats give birth. (See my post #57 from 2004)
3. The mode of contamination by Marburg virus appears to be different, however. It does not appear to need any intermediary to be pathogenic for humans, as foreseen from the data on Marburg epidemic outbreaks.
In one outbreak, which raged in the north-east of DRC in 2000, most people infected worked in a goldmine, which turned out to be the refuge for a large colony of Egyptian rousettes. During the second epidemic, in Angola, the first victims were children who had gathered fruit from trees where a large population of this species of fruit bat roosted.
4. R. aegyptiacus - Carries both antibodies and viral RNA fragments - strongly suggesting that this bat species is a non-symptom developing carrier of the Marburg virus - (i.e.) the natural reservoir.
MA
75 posted on 10/09/2007 7:58:39 AM PDT by Mother Abigail
http://www.freerepublic.com/focus/news/1935001/posts?page=6#6
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MA's original post was in 2004 and I reposted it here as part of my attempt to "keep it real".
Congratulations Mother Abigail - excellent work. It is my great privilege to know you.
James 9-07-09
Ping.
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These viruses scare the hell out of me.
Bookmarked. Thank you.
Mostly African outbreaks of these, but I can assure you: this is some scarey sh**
I am sure happy the US doesn’t have the fruit bats...we’d have more problems.
Thanks for this information! It is good to read progress on finding the source.
One in a lab in Alexandria, VA:
“US doesn’t have the fruit bats”
*snicker* But we have plenty of fruits!
OHHHHHHH, we don’t need no water let the mother effing roof burn! *celebration dance*
>>US doesn’t have the fruit bats
Fruit Rats, not Bats.
fascinating!
Awesome book. As was “Demon in the Freezer” by the same author.
You are quite welcome.
Thank you for visiting.
Pinging Judith Anne (Marburg Surveillance Project threads, where we speculated about a bat vector/reservoir in 2005)
I remember that; and the early pediatric cases seemed consistent with children gathering fruit to eat, that the bats may have left the virus on during the preceding night...
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The pet shop man's brother was lyin'.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...Sort of related to undocumented or poorly documented movements and migrations in ancient and prehistoric times. |
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It’s nice that they may have pin pointed the carrier. Do any of you remember the hysteria that was generated over ebola and marburg? We were all going to die, it was going to sweep the world and kill us all, similar to what the swine flu hysteria is like except in the case of ebola they could point to real victims dying in droves. The thing about both of these viruses are they are so virulent they die out fast because they kill their host so quickly. They didn’t spread all over the world and kill us all, or even very many compared to the world population. Just one of many examples of the left trying to ramp up world hysteria for an imposition of totalitarian laws.
If the bats left the virus on the fruit the previous night, it’s a hardy bastich. Most viruses, IIRC, expire rapidly when exposed to air-ambient conditions.
I would submit Barking Moonbats™, carriers of the libtard virus, are a greater threat. The virus attacks on multiple fronts creating symptoms not unlike those found in the Ebola and Marburg variety. The libtard virus however, can bleed an entire nation to death.
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