The Current Pandemic

This pandemic is not the first and will not be the last until there's balance in nature. Anjani Ganase considers recent disease and die-off, and wonders what it will take for Homo Sapiens to understand and respond to the actual causes

We are in the midst of crisis - not a social one, but a biological one. The mass spread of the novel coronavirus (Covid-19) that originated from Wuhan China as a result of the virus spilling over from an animal meat used in wildlife trade has now managed to infect the farthest reaches of the world, including isolated tribes in the Amazon, and brought our lives to a literal halt. While we are acutely aware of the diseases that directly impact our lives and livelihoods, we must consider the origins of these diseases as more than simply bad habits or bad luck. This is because the spread of diseases has increased in recent years, and we are not the only victims, but also our livestock and food crops, as well as much wildlife (Cunningham et al 2012). Humans play a major role in the transmission of novel diseases through the exploitation of natural spaces; and such disease epidemics can be devastating to wildlife. Disease is one of the top five drivers of global extinction. 

In ecology, the historical factors for disease outbreak or the spread of an invasive species are largely related to the activities of man through a number of ways. Humans have invaded almost every natural space on earth for the purpose of resource extraction. The exotic wildlife industry and trade removes wildlife from native habitats for sale of live animals and meat, and in some cases the trade unintentionally carries with it, pests and microbes. 

Continued interaction with natural ecosystems also results in habitat degradation. As we lay down infrastructure, such as roads, that disturb the natural ecosystems, we significantly increase the interaction of our populations with these novel ecosystems. The degraded ecosystems and vulnerable wildlife may move into human landscapes in search of food, using the very same clearings and roads to get there. In the densely populated city of Mumbai, India, leopards can be seen hunting stray dogs and livestock in the streets at night. While these invasive predators are very visible consequences of habitat and prey loss, the spillover of microbes - viruses, bacteria and fungi - into our constructed habitats is far less obvious but very likely to wreak substantial and far-reaching havoc. Here are some examples of some devastating impacts on wildlife as a result of disease spread by human activities.

Panamanian Golden Frog: pandemics among amphibian species have resulted in extinctions on a global scale. Photo by Anjani Ganase

Global amphibian die-off

Chytridiomycosis is a virulent disease stemming from a chytrid fungus and has threatened the populations of over 500 species of amphibians (frogs and salamanders) around the world and has even resulted in the extinction of 90 species! Even though fungal spores are highly dispersible, the global spread of the fungus is most likely the result of the human food trade. Even though the fungus is thought to have originated in Asia, it has managed to infect ecosystems in the rainforests of the Americas, as well as in Australia, over the last fifty years with severe loss in amphibian biodiversity across several regions.

Ebola threatens wild apes

We all remember the Ebola outbreak of 2014–2016 that plagued communities of West and Central Africa. Ebola is thought to have originated from bats and has been around since the 1970s causing outbreaks with up to 90 % mortality in local communities for decades. Owing to the increased interactions between humans and the apes (gorillas and chimpanzees) because of hunting and land exploitations, whenever there is a flare up in ebola outbreaks in human populations, neighbouring ape populations have been observed to also show significant infections and corresponding deaths. For example in one outbreak about 5000 gorillas died as a result. Gorillas which were previously listed as endangered on the IUCN Red List are now being considered critically endangered as this virus alone has killed 33 % of their population in the last 14 years.

The rinderpest migration

Lions of Kenya: loss of habitat and prey species turned some lions into man-eaters. Photos by Anjani Ganase

During the 18th century in Europe, a disease known as rinderpest often plagued the cattle (all hoofed animals) in different villages across Europe. The disease was thought to originate in the Steppes Region between Europe and Asia. The footprint of the disease soon began to follow the movements of marauding men and war beyond the boundaries of Europe. After being pillaged, village livestock would fall ill and succumb to this disease. As Europeans began to expand exploration routes to Indonesia, Philippines and parts of Asia, the disease spread rapidly resulting in a near wipe out of cattle in these lands. Outbreaks in Africa were especially severe as many of the natural ecosystems were dependent on herds of hoofed animals including Buffalo, Antelope and Giraffes; all of these suffered significant declines in populations. In Kenya, the consequences of this disease came full circle. In the absence of their usual prey, lions developed a taste for humans as prey and so was born the man-eating lions of Tsavo who still have this tendency over 100 years later.

As we learn the lessons of the spread of Covid 19 – understanding the basis of the spread of the virus and the methods to mitigate – we need to consider the broader ecological context of how ecosystems function, along with the consequences of our exploitations. Strategies of mitigation can also take clues from the very ecosystem where the disease originated. For example, we need to appreciate the importance of high biodiversity, even as we identify disease hot spots. We must curb the practices that degrade ecosystems as well those that lead to exportation of the disease.

Maintaining high biodiversity lowers the chances of a wipe out of populations, harvests or wildlife to a single disease. Monitoring of natural spaces requires conservation efforts to limit exploitations. Unfortunately, these disease outbreaks will be exacerbated by man-made climate change, which has already degraded ecosystems and shifted natural ecological barriers as a result of our carbon emissions. This will surely allow diseases and their vectors to invade new territories – tropical and temperate regions. 

Have we reached a tipping point with Covid-19? It may not be too late to change our all-too-human characteristic, which is believing that we are “masters of all we survey.” Can we un-learn greed? Most important of all, can we behave as if all humans belong to the same species, and re-assess how much we have in common with all creatures that share planet Earth.

References:

Bermejo, M., Rodríguez-Teijeiro, J. D., Illera, G., Barroso, A., Vilà, C., & Walsh, P. D. (2006). Ebola outbreak killed 5000 gorillas. Science, 314(5805), 1564-1564.

Crowl, T. A., Crist, T. O., Parmenter, R. R., Belovsky, G., & Lugo, A. E. (2008). The spread of invasive species and infectious disease as drivers of ecosystem change. Frontiers in Ecology and the Environment, 6(5), 238-246.

Cunningham, A. A., Dobson, A. P., & Hudson, P. J. (2012). Disease invasion: impacts on biodiversity and human health

Fisher, M. C., Henk, D. A., Briggs, C. J., Brownstein, J. S., Madoff, L. C., McCraw, S. L., & Gurr, S. J. (2012). Emerging fungal threats to animal, plant and ecosystem health. Nature, 484(7393), 186-194.

Lindahl, J. F., & Grace, D. (2015). The consequences of human actions on risks for infectious diseases: a review. Infection ecology & epidemiology, 5(1), 30048.

Peterhans, J. C. K., & Gnoske, T. P. (2001). The science of ‘man-eating*’among lions panthera leo with a reconstruction of the natural history of the ‘man-eaters of Tsavo’. Journal of East African Natural History, 90(1), 1-40.

Scheele, B. C., Pasmans, F., Skerratt, L. F., Berger, L., Martel, A., Beukema, W., ... & De la Riva, I. (2019). Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity. Science, 363(6434), 1459-1463.