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  • Ebola outbreaks linked to forest loss, new study finds

Ebola outbreaks linked to forest loss, new study finds

A river rund through Mau Forest in Kenya. Photo by P. Shepherd/CIFOR
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FTA COMMUNICATIONS TEAM

Wildmeat is sold at Bartica market in Guyana. Photo by M. Lopez/CIFOR

Scientists track the disease to the edge of newly cleared forests.

News of an Ebola Viral Disease (EVD) outbreak strikes fear not only in Africa where it originates, but around the world. In humans, the virus produces severe symptoms such as bleeding from the eyes, nose and mouth, loss of consciousness, seizures and eventual death.

First discovered in 1976 in Central Africa, the worst outbreak happened between 2014-2016 when the virus rapidly spread through Liberia, Sierra Leone and Guinea, killing more than 11,000 men, women and children. Cases were also reported in Mali, Nigeria, Senegal, Spain, Italy, the United Kingdom and the United States. With no known cure, governments must rely on prevention and control strategies to contain new outbreaks.

But in a new study, scientists from the Center for International Forestry Research (CIFOR), Spain’s Universidad de Malaga and other partner institutions have uncovered a vital piece of the Ebola puzzle — when and where outbreaks can occur.

Watch: Let’s talk about bushmeat

TIMING IS EVERYTHING

“Since Ebola is transmitted to humans from wild animals we were initially very interested in the link between the virus and bushmeat practices,” says Professor John E. Fa, a Senior Associate at CIFOR and a Professor at the UK’s Manchester Metropolitan University.

“This led us to the next question: we knew there was no evidence that Ebola happens in cycles, so we asked, ‘What other conditions on the ground are there to encourage this virus to flourish and infect people?’” says Fa.

A river runs through Mau Forest in Kenya. Photo by P. Shepherd/CIFOR

The team — made up of practitioners, landscape ecologists and modellers, the latter led by Dr. Jesus Olivero of the Faculty of Sciences in Malaga — joined forces to investigate patterns of forest loss in areas where Ebola disease outbreaks had been recorded, and other sites where no outbreaks had occurred. The question to be answered was whether there were substantial differences in the rates and extent of deforestation in these two distinct types of sites.

“The comparison is remarkable. In the outbreak areas, it’s not just more deforestation, but there is also greater forest fragmentation,” says Olivero.

The scientists point out that as large forest blocks are broken up into smaller fragments, this may become an open invitation for new instances of contact to take place between humans and potential natural carriers, thereby increasing the risk of an outbreak.

Although the possible link between forest loss and zoonotic disease has been suggested before, the findings of the present work provide strong evidence of an association between Ebola outbreak locations and deforestation. The breakthrough in the new study occurred when the team noted a pattern in the timing of deforestation prior to the outbreaks.

“For the first time, we saw a direct correlation between forest fragmentation and when EVD outbreaks happen,” says Olivero.

“We found that EVD outbreaks tended to occur in areas that experienced forest loss up to two years prior.”

Read more: Eating and conserving bushmeat in Africa

GETTING A HEADS UP

The research team says the data could lead to the development of an early warning system, which means governments in Ebola risk regions can get a head start on implementing interventions. This is key, because most EVD outbreaks happen in remote, rural communities where there are few resources.

“Once we know where these potential hotspots are, we can create a map showing where an outbreak is likely to occur and mobilize people and resources to monitor local communities,” says Fa.

This means that surveillance and medical teams, as well as community awareness activities, could make preparations in identified high-risk areas before the virus strikes and, in doing so, save lives.

AN OUNCE OF PREVENTION 

A sign advertises wild meat in Guyana. Photo by M. Lopez/CIFOR

The new study clearly suggests that preserving forested areas must be a high priority for nations throughout the world.

“Tropical rainforests are chock-a-block with species of all kinds, including pathogens, which means that for such a high diversity of animal hosts there are corresponding parasites, viruses, and so on,” notes Fa.

“Our feeling is that once you start playing around with an ecosystem, you might have a flurry of activity of viruses that may even start looking for new hosts,” he adds.

Fa says much more needs to be done to fully understand how EVD outbreaks occur, and how the virus is transmitted. The team is currently looking at how outbreaks may be influenced by climate, and how potential Ebola host animals, such as bats, may be linked to deforestation.

“It is now fundamental to go to the field to find out what creates disease flurries, and also to do more research into different types of forests with different levels of deforestation. We need to know what happens to the species, what happens to the virus, in these areas,” he says.

Fa adds that it’s crucial to look at the big picture, at how emerging infectious diseases like Ebola are moving out of remote areas and infecting the general public, and the role that nature plays.

“We see the importance of keeping biodiversity intact,” he concludes.

Watch: Future solutions for bushmeat in Colombia

By Suzanna Dayne, originally published at CIFOR’s Forests News

This research is part of CIFOR’s Bushmeat Research Initiative. For more information on this topic, please contact John E. Fa at [email protected] or Jesus Olivero at [email protected].


This research forms part of the CGIAR Research Program on Forests, Trees and Agroforestry, which is supported by CGIAR Fund Donors. It is also supported by UK aid from the UK Government and USAID. 

  • Home
  • Ebola outbreaks linked to forest loss, new study finds

Ebola outbreaks linked to forest loss, new study finds

A river rund through Mau Forest in Kenya. Photo by P. Shepherd/CIFOR
Posted by

FTA COMMUNICATIONS TEAM

Wildmeat is sold at Bartica market in Guyana. Photo by M. Lopez/CIFOR

Scientists track the disease to the edge of newly cleared forests.

News of an Ebola Viral Disease (EVD) outbreak strikes fear not only in Africa where it originates, but around the world. In humans, the virus produces severe symptoms such as bleeding from the eyes, nose and mouth, loss of consciousness, seizures and eventual death.

First discovered in 1976 in Central Africa, the worst outbreak happened between 2014-2016 when the virus rapidly spread through Liberia, Sierra Leone and Guinea, killing more than 11,000 men, women and children. Cases were also reported in Mali, Nigeria, Senegal, Spain, Italy, the United Kingdom and the United States. With no known cure, governments must rely on prevention and control strategies to contain new outbreaks.

But in a new study, scientists from the Center for International Forestry Research (CIFOR), Spain’s Universidad de Malaga and other partner institutions have uncovered a vital piece of the Ebola puzzle — when and where outbreaks can occur.

Watch: Let’s talk about bushmeat

TIMING IS EVERYTHING

“Since Ebola is transmitted to humans from wild animals we were initially very interested in the link between the virus and bushmeat practices,” says Professor John E. Fa, a Senior Associate at CIFOR and a Professor at the UK’s Manchester Metropolitan University.

“This led us to the next question: we knew there was no evidence that Ebola happens in cycles, so we asked, ‘What other conditions on the ground are there to encourage this virus to flourish and infect people?’” says Fa.

A river runs through Mau Forest in Kenya. Photo by P. Shepherd/CIFOR

The team — made up of practitioners, landscape ecologists and modellers, the latter led by Dr. Jesus Olivero of the Faculty of Sciences in Malaga — joined forces to investigate patterns of forest loss in areas where Ebola disease outbreaks had been recorded, and other sites where no outbreaks had occurred. The question to be answered was whether there were substantial differences in the rates and extent of deforestation in these two distinct types of sites.

“The comparison is remarkable. In the outbreak areas, it’s not just more deforestation, but there is also greater forest fragmentation,” says Olivero.

The scientists point out that as large forest blocks are broken up into smaller fragments, this may become an open invitation for new instances of contact to take place between humans and potential natural carriers, thereby increasing the risk of an outbreak.

Although the possible link between forest loss and zoonotic disease has been suggested before, the findings of the present work provide strong evidence of an association between Ebola outbreak locations and deforestation. The breakthrough in the new study occurred when the team noted a pattern in the timing of deforestation prior to the outbreaks.

“For the first time, we saw a direct correlation between forest fragmentation and when EVD outbreaks happen,” says Olivero.

“We found that EVD outbreaks tended to occur in areas that experienced forest loss up to two years prior.”

Read more: Eating and conserving bushmeat in Africa

GETTING A HEADS UP

The research team says the data could lead to the development of an early warning system, which means governments in Ebola risk regions can get a head start on implementing interventions. This is key, because most EVD outbreaks happen in remote, rural communities where there are few resources.

“Once we know where these potential hotspots are, we can create a map showing where an outbreak is likely to occur and mobilize people and resources to monitor local communities,” says Fa.

This means that surveillance and medical teams, as well as community awareness activities, could make preparations in identified high-risk areas before the virus strikes and, in doing so, save lives.

AN OUNCE OF PREVENTION 

A sign advertises wild meat in Guyana. Photo by M. Lopez/CIFOR

The new study clearly suggests that preserving forested areas must be a high priority for nations throughout the world.

“Tropical rainforests are chock-a-block with species of all kinds, including pathogens, which means that for such a high diversity of animal hosts there are corresponding parasites, viruses, and so on,” notes Fa.

“Our feeling is that once you start playing around with an ecosystem, you might have a flurry of activity of viruses that may even start looking for new hosts,” he adds.

Fa says much more needs to be done to fully understand how EVD outbreaks occur, and how the virus is transmitted. The team is currently looking at how outbreaks may be influenced by climate, and how potential Ebola host animals, such as bats, may be linked to deforestation.

“It is now fundamental to go to the field to find out what creates disease flurries, and also to do more research into different types of forests with different levels of deforestation. We need to know what happens to the species, what happens to the virus, in these areas,” he says.

Fa adds that it’s crucial to look at the big picture, at how emerging infectious diseases like Ebola are moving out of remote areas and infecting the general public, and the role that nature plays.

“We see the importance of keeping biodiversity intact,” he concludes.

Watch: Future solutions for bushmeat in Colombia

By Suzanna Dayne, originally published at CIFOR’s Forests News

This research is part of CIFOR’s Bushmeat Research Initiative. For more information on this topic, please contact John E. Fa at [email protected] or Jesus Olivero at [email protected].


This research forms part of the CGIAR Research Program on Forests, Trees and Agroforestry, which is supported by CGIAR Fund Donors. It is also supported by UK aid from the UK Government and USAID. 

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  • A new method for tracking Ebola could help prevent outbreaks

A new method for tracking Ebola could help prevent outbreaks

Colorized scanning electron micrograph of Ebola virus particles (red) in extracellular space between infected African green monkey kidney cells. Photo: NIAID
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By Catriona Cuft-Cosworth, originally published at Forests News

Colorized scanning electron micrograph of Ebola virus particles (red) in extracellular space between infected African green monkey kidney cells. Photo: NIAID
Colorized scanning electron micrograph of Ebola virus particles (red) in extracellular space between infected African green monkey kidney cells. Photo: NIAID

The ongoing Ebola virus outbreak in West Africa has claimed more than 11,000 lives since March 2014. Yet we still know very little about the conditions in which the virus thrives and how it spreads to humans.

Some answers may be found in a groundbreaking new study that borrows techniques from biology and geography to map out hotspots where the virus may be lurking.

A research team led by scientists John Fa and Robert Nasi from the Center for International Forestry Research (CIFOR) together with Jesús Olivero and colleagues from the University of Málaga, including US virologist Jean Paul Gonzalez and Zoological Society of London wildlife epidemiologist Andrew Cunningham, took a biogeographical approach to mapping favorable conditions for the Ebola virus, both in terms of environment and the presence of animals as potential hosts.

The resulting map from the study suggests that favorable conditions for Ebola are more widespread than suspected, stretching across 17 countries throughout West and Central Africa, and as far as the East African Lakes Region.
Preconceptions that only bats are to blame for carrying the virus were disregarded, with analysis extended to 64 species including rodents, primates, hoofed animals, a civet and a shrew as potential reservoirs of Ebola virus. Photo: Daniel Tiveau/CIFOR
Preconceptions that only bats are to blame for carrying the virus were disregarded, with analysis extended to 64 species including rodents, primates, hoofed animals, a civet and a shrew as potential reservoirs of Ebola virus. Photo: Daniel Tiveau/CIFOR

It also finds a strong link between Ebola and tropical rainforests, and suggests a list of more than 60 wild animals that require further investigation as potential carriers of the disease.

The findings could help save lives. “This information is essential for the development of early warning systems aiming to optimize the efficacy of prevention measures,” said Olivero.

TRACKING A VIRUS

Olivero and his team are among the world’s leading researchers in the area of “biogeography”, or the science of mapping biological patterns across time and space.

Biogeographic mapping allows scientists to not only analyze the distribution of an organism, but also to predict where that organism may be found based on the existence of favorable environmental conditions.

As a virus, Ebola is in fact an organism. Recognizing this, Olivero and colleagues took biogeographic mapping techniques that are normally used for animals, and applied them to the case of a virus.

Geographical information system (GIS) software was used to map the distribution of favorable environments for Ebola to occur in, as well as the spread of mammals known to have died from, or been infected by, the virus.

“Our findings provide new information about how the Ebola virus is distributed in the wild, before it is transmitted from humans to humans,” said Olivero.

Preconceptions that only bats are to blame for carrying the virus were disregarded, with analysis extended to 64 species including rodents, primates, hoofed animals, a civet and a shrew as potential reservoirs ofEbola virus.

The resulting map found a wider than expected spread of Ebola both among mammal populations and across the African continent.

THE HUMAN CONNECTION
13652907
Click to read the study

So what do the findings mean for humans? This is where the work of CIFOR scientists John Fa and Robert Nasi comes in. Fa and Nasi are experts on bushmeat, or wild animals harvested for food and non-food purposes.

One of the major causes of transmission for Ebola is the hunting, butchering and consumption of wild animals. But putting a blanket ban on bushmeat is not a viable measure – and neither is hunting all species suspected as carriers.

“We don’t want people to be alarmed that there are so many different species, and start killing as many as possible,” said Fa.

“We have to have very clear and realistic ways of trying to stop the transmission from infected animals to people without necessarily stopping people from doing what they’ve done, which is essentially hunting for food.”

Fa said that working with at-risk hunters and communities will be critical for stopping the spillover of infection from animals to humans.

Further research into the communities of animals identified in the study, and how their habitats are affected by human activities such as deforestation and urbanization, is also needed.

In the meantime, it’s hoped that the new method of mapping will help identify hotspots for Ebola and prevent contagion.

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  • Mammalian biogeography and the Ebola virus in Africa

Mammalian biogeography and the Ebola virus in Africa

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Authors: Olivero, J.; Fa, J.E.; Real, R.; Farfán, M.A.; Márquez, A.L.; Vargas, J.M.; Paul Gonzales, J.; Cunningham, A.A.; Nasi, R.

  1. Ebola virus is responsible for the fatal Ebola virus disease (EVD).
  2. Identifying the distribution area of the Ebola virus is crucial for understanding the risk factors conditioning the emergence of new EVD cases. Existing distribution models have underrepresented the potential contribution that reservoir species and vulnerable species make in sustaining the presence of the virus.
  3. In this paper, we map favourable areas for Ebola virus in Africa according to environmental and zoogeographical descriptors, independent of human-to-human transmissions. We combine two different biogeographical approaches: analysis of mammalian distribution types (chorotypes), and distribution modelling of the Ebola virus.
  4. We first obtain a model defining the distribution of environmentally favourable areas for the presence of Ebola virus. Based on a review of mammal taxa affected by or suspected of exposure to the Ebola virus, we model favourable areas again, this time according to mammalian chorotypes. We then build a combined model in which both the environment and mammalian distributions explain the favourable areas for Ebola virus in the wild.
  5. We demonstrate that mammalian biogeography contributes to explaining the distribution of Ebola virus in Africa, although vegetation may also underscore clear limits to the presence of the virus. Our model suggests that the Ebola virus may be even more widespread than previously suspected, given that additional favourable areas are found throughout the coastal areas of West and Central Africa, stretching from Cameroon to Guinea, and extend further East into the East African Lakes region.
  6. Our findings show that the most favourable area for the Ebola virus is significantly associated with the presence of the virus in non-human mammals. Core areas are surrounded by regions of intermediate favourability, in which human infections of unknown source were found. The difference in association between humans and other mammals and the virus may offer further insights on how EVD can spread.

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