Straw-colored fruit bat (Eidolon helvum) at the Zoological Garden Berlin, Germany. This species, along with other fruit bats, is present in the Ebola impacted area and may have been a carrier. Photo by: Fritz Geller-Grimm/Creative Commons 2.5.

The Ebola outbreak in West Africa may have been the result of complex economic and agricultural policies developed by authorities in Guinea and Liberia, according to a new commentary in Environment and Planning A. Looking at the economic activities around villages where Ebola first emerged, the investigators analyzed a shift in land-use activities in Guinea’s forested region, particularly an increase in oil palm (Elaeis guineensis) cultivation.

The researchers write that this shift could be linked to governmental policy promoting “neoliberal structural adjustment” that opens domestic production to global markets. Using what they called “a palm oil hypothesis,” they conclude that Ebola may have crossed from the environment into humans through a rise in palm oil plantations.

Agriculture in the region had been characterized by coffee, cocoa, the kola nut, and by slash-and-burn farming. Such farming involves planting maize and rice initially, followed by cassava and peanuts during the second year. But these agroforestry practices changed recently with the introduction of improved palm oil production. Beginning in 2007, the Guinean government began to export palm oil and planned to ramp up production to export 84,000 tons in 2015, more than half of which would come from forested Guinean plantations.

Land use pattern near Gueckedou, Guinea. Landscape is a mosaic of villages surrounded by dense vegetation interspersed by oil palm plots (red) and patches of forest. (top). General or spatial scale north of Gueckedou. (lower group). Finer scale west of Meliandou.

The researchers noted that since 2006 the Guinean Oil Palm and Rubber Company, a state corporation founded in 1987, has been leading the effort to produce hybrid palms to increase commodity exports. An oil palm mill, financed by the European Investment Bank, enabled the company to produce four times its previous output. The new mill also fundamentally transformed the artisanal oil palm extraction that characterized this area as recently as 2010. ‘Land grabbing’ to enable increased mill capacity included forceful removal of indigenous landowners by police. Farmers who once grew coffee, cocoa, and kola nut now prefer to grow hybrid palm oil for increased yield and income.

Similar changes in agroforestry and industrialization could be seen generations ago in Guinea’s neighbor, Liberia, according to the researchers. They began with a 1926 Firestone rubber plantation, which established the basis for an “open door policy” in the 1950s. Post-WWII neoliberal ideology opened Liberia’s door to foreign investors, a decision that saw surges in the mining and agricultural sectors. A recent move has been directed toward oil palm production in Liberia similar to Guinea.

“More recently, alongside a longer national tradition of wage labor, international logging, mining, and agro-industrial companies, including palm oil companies Sime Darby (Malaysia), Equatorial Palm Oil (UK), Golden Veroleum (Indonesia), have partaken in large-scale land expropriation totaling a third of the country’s land surface,” the researchers write.

A Palm Oil Hypothesis

The first victim of the current Ebola outbreak in West Africa (“patient zero” in epidemiological jargon) was traced to a two-year-old boy and his sister in the northern part of Gueckedou, a town of 20,000 people in Guinea. However, focusing on patient zero “may miss the point” according to the study. Researchers write that “Ebola may have been circulating for years” in this area, and “local populations may even have recognized” its presence. Looking at other researcher, the scientists point out that Zaire’s strain of the Ebola virus was found in antibodies of people in Sierra Leone dating back five years. Further analysis finds that the virus may even have entered West Africa a decade earlier.

The researchers found that the land around Gueckedou, i.e. “ground zero,” contains islands of monoculture palm plantations. They also noted that “land use appears as a mosaic of local villages surrounded by dense vegetation interspersed with fruit-tree plantations, an environment also suitable for frugivore bats (Pteropodidae), a key Ebola reservoir.” Frugivore bats, which are believed to be the most likely source of the current outbreak, are fruit-eating bats also known as flying foxes.

Bats are thought to be reservoirs of Ebola and are not affected by it. They pass it on to other animals, in turn infecting humans through bush meat processing. Courtesy, Centers for Disease Control. Click to enlarge.

Palm trees offer desirable habitat for bats for three reasons: the bats eat the palm fruits; they gain shelter from the sun under the thick palm leaves; and the trails created in monoculture palm plantations “permit easy movement between roosting and foraging sites” for bats, according to the authors.

While palm picking occurs throughout the year around Gueckedou, the greatest harvest occurs at the onset of the dry season. This, according to the authors, is about the time the outbreak started. They further indicated that huge numbers of bats were roosting in both fruit and palm trees several weeks before the outbreak, one of the clues that led to their theory.

In seeking the Ebola link between fruit bats and humans, the researchers said that a default meat-eating explanation (the belief that people get the Ebola virus from eating bushmeat, particularly bats and monkeys) may not capture the complexities of Ebola virus transmission from its natural host to humans. Instead, they believe that deforestation, including that resulting from oil palm plantations, could change the foraging nature of the fruit bats. After losing their natural habitat and foraging sites, flying foxes may become more attached to eating garden crops, thus “expanding interfaces among bats, humans, and livestock,” the authors write. The researchers also noted that in Bangladesh, fruit bats transmit Nipah virus to humans by urinating on cultivated oil palm fruits.

Oil palm plantation in Cameroon. Malaysia and Indonesia are the biggest producers of oil palm, but the crop is taking off in Africa as well leading to increased deforestation. Photo by: Marco Schmidt/Creative Commons 2.5.

Using a mathematical model, the authors also compared the West African Ebola outbreak to the emergence of poliomyelitis in post-war England and Wales. Poliomyelitis became an epidemic as a result of increased per capita affluence and modern transportation, particularly the increasing number of private automobiles. For Ebola, the palm oil’s expanding value-added network and subsequent disturbance of agricultural practices (which may have been serving as barriers to the virus), may have allowed the virus to migrate from its natural host into human population.

By commoditizing palm oil fruit trees, forested Guinea may have lowered “the ecosystemic temperature” below the level where Ebola can be “sterilized” and controlled, according to the paper. This degraded ecosystem could have enabled transmission of the Ebola virus from its natural hosts to humans. The authors concluded that whether their inductive model defines the West Africa Ebola outbreak “remains to be ascertained,” especially given the complexity associated with the Guinean agricultural sector.

Citations:

• Wallace, R. G., Gilbert, M., Wallace, R., Pittiglio, C., Mattioli, R., & Kock, R. (2014). Did Ebola emerge in West Africa by a policy-driven phase change in agroecology? Ebola’s social context. Environment and Planning A, 46, 11, 2533-2542.

Emmanuel K. Urey, Liberian Land Commission and Nelson Institute Graduate Student, University of Wisconsin-Madison.

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