Global Epidemics and Pandemics: COVID-19

Red Deer
Copyright Mike Brown

The emergence of zoonotic diseases is closely related to high human population density and high wildlife diversity, and is linked to human-caused changes such as deforestation and the expansion of agricultural land, intensified livestock production, and increased wildlife harvesting (World Wildlife Fund, 2020).

The emergence and spread of zoonotic diseases such as Nipah in Malaysia in 1998, SARS in China in 2003, Ebola in West Africa in 2013-16 and many other diseases have all been linked to human-caused changes to the natural environment. Similarly, although the origins of COVID-19 remain uncertain, 60% of emerging infectious diseases come from animals, and nearly 75% of these from wild animals (World Wildlife Fund, 2020). However, the spread of zoonotic diseases from wildlife directly to human host is uncommon. Instead, domestic animals often serve to bridge this gap. The growing demand for milk and meat, driven primarily by fast-growing urban populations in developing countries has resulted in demand for livestock products. This has led to more intensive agricultural production where large populations of high yielding and genetically similar agricultural animals are kept in close proximity. Consequently, these animals are not only exposed to more contact opportunities but they also lack the genetic diversity that helps resist the spread of disease, a vulnerability known as the monoculture effect. Similarly, intensification of livestock production systems also contributes to increased fertiliser use (for feeding and fodder) and increased production of livestock waste, which can create nutrient rich environments that promote the spread of such diseases (Jones et al., 2013).

Responding to zoonotic diseases

Whilst the implementation of a global vaccination programme to reduce the spread of COVID-19 amongst humans is an important short-term strategy to deal with the immediate impacts of the disease, ultimately there is a broader need to consider the social and economic consequences of environmental degradation and the importance of protecting human health and security to reduce the risk of such diseases from emerging in the first instance. This will require a concerted global effort and a long-term strategic approach to reduce human-caused changes such as deforestation, the expansion of agricultural land, the intensification of livestock production, and the increased harvesting of wildlife. Only when the root cause of such zoonotic diseases are addressed can we expect to see a reduction in their emergence and prevalence in the future (World Wildlife Fund, 2020).