Human health and snow leopards: how are they related?

Since the beginning of 2020, most of us have found ourselves living in a dystopian reality caused by SARS – CoV-2, the virus responsible for the COVID-19 pandemic. The virus has already caused unimaginable loss of human life –more than four million known fatalities as of July — with actual numbers likely to be much higher.

Yet, the COVID-19 pandemic is only the latest in a long line of disease outbreaks that the world has seen through human history, including recent ones such as HIV/AIDS, Ebola and SARS. Three-fourths of these newly emerging diseases are thought to be zoonotic.

What are zoonotic diseases and what do they have to do with snow leopards and their habitats? To address these questions, Dr. Charu Mishra, Executive Director of the Trust, teamed up with other SLT Scientists and international collaborators including human and veterinary doctors. They have just published their views and findings in Ambio, the journal of the Royal Swedish Academy of Sciences.

Simply put, zoonotic diseases are those that are transmitted from animals to humans. Pathogens, or the microorganisms that cause diseases, can sometimes “jump” the species barrier to infect humans, and in rare cases they become transmissible between humans, going on to become epidemics or even pandemics. There can also be reverse zoonoses, where the pathogen may jump from humans to animals. In the past, most of these outbreaks have originated in tropical or temperate zones, where there’s a high density of people, who are often in close contact with each other and with wildlife.

Snow leopard habitats are typically not considered high risk for disease outbreaks. This may be because of several reasons – the extreme cold environments, relatively low density of people and wildlife, lack of adequate research on disease, and partly because models that predict future outbreaks rely on information from past outbreaks, which are not known to have occurred in these high mountainous regions.

In their paper, Charu and his colleagues show how this is changing. Local social, ecological, and economic conditions, interacting with climate change and globalization, are increasing the risk of disease outbreaks in snow leopard landscapes. Their review shows that despite limited research, several pathogens that have the potential to cause serious disease outbreaks, such as anthrax, rabies, and plague, are already known to occur in these High Asian landscapes. The right conditions could cause an outbreak.

Snow leopards have large home ranges and frequently move over large distances, interacting with each other when they travel together or share kills. They also interact with wild ungulates and livestock when they hunt and kill them. Even these limited exposures could give pathogens ample opportunities to hitchhike on snow leopards and spread across the range.

Similarly, ibex, argali and other wild herbivores, which are prey species for the snow leopard, can spread disease to livestock as they are closely related, share the same pastures and water sources and eat similar plants. They might also be more susceptible to disease as they move in herds and their body condition and general health is often seasonally compromised because of long, harsh winters and competition with livestock. Rodents, hares and rabbits — known to carry over 60 zoonotic pathogens — live in close proximity to humans and can pose a risk of disease transfer. High Asian landscapes are favorite spots for migrating, attracting birds from densely populated regions in South-West Africa and Southern Asia. Birds can also potentially carry disease as they traverse the globe, and can spread disease when they come in contact with people, wildlife or domestic ungulates at watering holes or in the pastures.

Local communities have been living in these landscapes for millennia. Yet, recent changes in the way people interact with their environment can increase the risk of a potential disease outbreak. For example, crop production is being intensified and homogenized, with new areas being brought under cultivation. This brings people closer to wild animals. Intensification and homogenization makes the integrity of the ecosystem weaker, causing the system to be more susceptible to disease outbreaks. Widespread use of antibiotics in livestock can lead to the emergence of resistant pathogens.

Similar conditions for outbreaks are created by increasing poaching, trade and consumption of wildlife. Poor wildlife law enforcement due to the remoteness of these regions can increase poaching.

All of this is compounded by the ever-present dual threats of globalization and climate change. The once remote snow leopard landscapes have seen an increase in infrastructure, mining, and other development, opening up these regions and increasing the movement of people and goods. People also move out for economic activities, and over the years these landscapes have become popular tourist destinations. These changes are accompanied by other issues of globalization and development such as pollution, new markets for wildlife trade and introduction of foreign pathogens and their vectors.

High mountain areas are among the most vulnerable to climate change and are warming at more than twice the average rate of the northern hemisphere. This can affect disease systems, weaken the existing barriers for pathogens and increase the frequency and intensity of species jumps and disease outbreaks. Human and veterinary health services available here are often inadequate to deal with the newly emerging threats.

As Charu says, “The purpose of our paper is to bring this intensifying risk of disease outbreaks to the forefront. As the COVID-19 pandemic has shown, these are not local problems – greater risk of disease in High Asia is a global issue. We will work with the range-country governments and international partners to promote ways of better understanding and controlling disease outbreaks in snow leopard habitats.”

The co-authors of this paper include Dr. Charu Mishra (India), Dr. Orjan Johansson (Sweden) and Dr. Gustaf Samelius (Sweden) of Snow Leopard Trust (SLT), Dr. NS Prashanth of the Institute of Public Health (India), Dr. Mathew Low of the Swedish University of Agricultural Sciences (Sweden), Dr. Carol Esson who is a Veterinary Professional (Australia), Dr. Suri Venkatachalam and Munib Khanyari of the Nature Conservation Foundation (NCF) (India) and Oxford University (UK).

Special thanks to Whitley Fund for Nature for funding part of this research.

The original paper in its entirety can be accessed here.