The environmental origins of Ebola must be tackled

A new study explores the environmental factors that give rise to outbreaks of Ebola virus disease (EVD). Jointly undertaken by the Environmental Foundation for Africa and the ERM Foundation, it posits a connection between rainforest fragmentation and this zoonotic [passed between animals and humans] disease. This is hypothesised to occur through increased contact between species that do not normally come into contact with each other or with humans. These include various bat species hypothesised to play a role in the transmission of the virus to humans.

As the recent west African epidemic, which began in December 2013, subsides, the question in the region and beyond is: how do we prevent this nightmare recurring? A timely reminder of the effect of this terrible disease was provided by the recent relapse of Scottish nurse Pauline Cafferkey, who contracted EVD in the course of her work.

So far, there have been more than 11,000 reported deaths, and double that number of survivors who have been both physically traumatised and socially stigmatised by the disease. Moreover, as of October 2014, the World Bank estimated that the economies of Guinea, Liberia and Sierra Leone could lose $1.6 billion (€1.4 billion) in economic activity during 2015.

More than this, the epidemic has generated existential fears, which I encountered on a visit to Sierra Leone last May. In societies where tactile behaviour is deeply rooted, prescriptions against physical contact impose uncomfortable limitations. Bans on public gatherings also distort social rituals, and the increased security measures create potential for abuse of power.

Assistance and resources

The international community, including governments and NGOs, devoted considerable medical assistance and resources to preventing the spread of the epidemic. To some extent, self-interest on the part of the international community was a motivation in this, as malaria and respiratory infections continue to be far greater killers than EVD in what remain some of the world’s poorest countries.

Nonetheless, EVD’s terrifying symptoms, including unexplained haemorrhaging, as well as its high mortality rate and the risk of wider contagion, demanded a response. Correctly, recovery plans for the region emphasise strengthening healthcare systems as a primary objective, but as the authors of the recent study point out, the prevailing approach is “to treat the next outbreak as inevitable”.

Economic recovery plans tend to take a business-as-usual approach that fails to consider adequately the environmental impact of economic activities. Thus, the regional organisation that the three EVD-affected states belong to, the Mano River Union, makes no direct reference in its post-EVD recovery plan to ways of reducing the risk of future outbreaks, or to any environmental protection measures that could support these.

The study contends that “forest loss or fragmentation, accompanied by hunting and the trade in bushmeat, drive contact between humans and wild reservoirs, and lead to infections”.

It is not certain that fruit bats are indeed the reservoir host of EVD that transmit the disease to human beings. “They may be part of a more complex chain of reservoirs and transmission chains between wild reservoirs and humans,” the study states.

Forest fragmentation that changes the behaviour of bats could have repercussions elsewhere. The bats’ altered behaviour may be having effects on other species that lead to a rare zoonotic occurrence.

The index case for the latest outbreak is believed to have been an unfortunate two-year-old boy from Méliandou, in Guinea, who came into contact with an infected bat while playing in the hollow of a tree. In that region, local land use is dominated by a pattern of subsistence farming commonly referred to as slash-and-burn agriculture.

Although mature trees are usually not a farmer’s first choice to clear, this task becomes a lot easier when aided by mechanisation used in industrial logging or mining. Relatively few large blocks of forest in that region of Guinea “have not been subjected to significant recent human manipulation”, according to the study’s authors.

Indeed, only a tiny proportion of the wider Upper Guinea rainforest belt remains unexploited, after a deforestation process that has accelerated considerably in recent decades. This has caused significant disturbance to bat populations, creating the preconditions, it appears, for an outbreak.

Time-lapse imagery

The study uses time-lapse satellite imagery to compare the outbreak in Guinea with others in Democratic Republic of Congo, Uganda and South Sudan. Similar environmental patterns of forest fragmentation can be observed, which are assumed to alter the mix of wild species in given locations. These species include bats, whose stress levels and immunological resistance levels are thereby potentially reduced.

The data connecting forest fragmentation with EVD outbreaks is not definitive, but the circumstantial evidence is compelling. Based on this evidence, donors should ensure that the environmental impact of economic activities, including agriculture, mining and logging, are assessed. People must be equipped with the skills and resources to produce food, energy and goods without damaging their environments.

Confronting EVD as simply a medical issue, without reference to the environmental context, is insufficient. Rolling out a vaccine is important, but we have no way of knowing the type or the severity of the next virus that emerges.

The study’s authors warn against demonising and eradicating animals that could harbour EVD. Quite apart from the morality of this, rainforests are highly complex ecosystems. Any such measures could have unintended dire consequences. Further, the identity of the reservoir host remains unclear and seems likely to be so for some time.

The study argues that donors and the authorities in the region should incorporate natural resource management and environmental impact as core evaluation criteria into their programmes “and not treat them as box-ticking exercises, or consider their job done by funding an isolated, sector-specific ‘forest and wild management’ project”.

Moreover, as the recent publication of the UN’s Sustainability Goals reminds us, biodiversity is essential for human flourishing. The limits of natural capital must be taken into account if economic activity is to be sustainable, and that is especially important for feeding populations.

The recent EVD outbreak highlights these crucial interdependencies, and the potentially catastrophic consequences of another outbreak are such that the burden is shared by us all.