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How Palm Oil, Fruit Bats and Deforestation Could Be Linked to Ebola Epidemic
There is no question that the tragic and deadly spread of Ebola in West Africa is tied to the longstanding poverty in the region, and exacerbated by a woefully inadequate medical response by the international health community.
Less obvious are the links between the rampant deforestation in the region, rapid agricultural development and the killer outbreak.
And while it would be imprudent and irresponsible to place the blame for the Ebola pandemic in any particular plantation in West Africa, there is a very interesting line of scientific inquiry underway that is finding that in general such plantations—including of palm oil—could play a significant role.
Researchers from the University of Minnesota, Food and Agricultural Organization (FAO) of United Nations and other institutions recently hypothesized that severe changes in the forest ecosystems disrupted an equilibrium that has been keeping the virus at bay in the wild.
In their commentary Did Ebola emerge in West Africa by a policy-driven phase change in agroecology? the authors review peer-reviewed studies showing that Ebola has been circulating in the region for years—and that this was not a “spontaneous outbreak,” as often reported. Rather, the authors suggest a new hypothesis: that the destruction of virgin forests and planting of vast monocultures forced the virus to “spill over” from its wildlife sources into human hosts.
Though bushmeat consumption is commonly thought of as the point of transfer of the virus from animals to humans and could indeed be to blame for some Ebola outbreaks, the authors point out that other likely sources are living animals driven out of the forest by expanding agricultural production.
Palm oil plantations, for instance, make a great home for fruit bats or Pteropodidae. As the authors note, “Bats migrate to oil palm for food and shelter from the heat while the plantations’ wide trails permit easy movement between roosting and foraging sites.”
Several species of these fruit bats are documented “reservoirs” for Ebola, which could then be transmitted to plantation workers and locals in nearby villages.
The authors make the case that intact native ecosystems usually contain pathogens like Ebola, but that clear cutting vast areas of forest can make the pathogen spread out of control. They argue, “clear-cutting Forested Guinea may have lowered the ecosystemic ‘temperature’ below which Ebola can be ‘sterilized’ and controlled.”
What's more, a report released by the World Health Organization this month helps validate the hypothesis that deforestation helped spread the virus. "Some evidence suggests that the resulting forest loss, estimated at more than 80%, brought potentially infected wild animals, and the bat species thought to be the virus’ natural reservoir, intocloser contact with human settlements," writes the WHO.
The first known infected victim—and 18-month old boy—had been seen playing in his backyard near a hollow tree infested with bats. Within three weeks, the boy and several of his family members had died of the infection.
This wouldn’t be the first time fruit bats could be linked to the spread of a virus. The Nipah virus in Bangladesh was spread by fruit bats urinating on the palm tree fruits that workers were cultivating.
A look at the land around the West African outbreaks fits well with this hypothesis. The first documented cases of infection in the current pandemic occurred in a small forest village just north of Guéckédou, in Southern Guinea near the borders of Liberia and Sierra Leone. Calling the area “ground zero” of the outbreak, researchers describe a “mosaic of local villages surrounded by dense vegetation interspersed with [oil palm] plantations.”
It’s also an ideal environment for fruit bats. And though oil-picking is a year round pursuit for local workers, the busiest time is the dry season—precisely when many Ebola outbreaks across Africa begin.
To be clear, this hypothesis was presented in a commentary section of an academic journal, so it is not a peer-reviewed piece of science. And another team more recently hypothesized the initial spillover took place when local children played with an insect-eating species of bat whose habitats are also being transformed by changes in regional agricultural production.
Whatever bat proves the source, the hypothesis that shifts in agricultural landscapes are promoting disease emergence should be taken seriously, especially as multinationals like Sime Darby and Olam continue to establish large-scale palm oil operations in Africa. The contention demands further research to inform land use planning decisions that minimize future risks of deadly diseases spreading out of control.
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