What zoologists should learn from a zoonotic pandemic



The best-known example of a zoonotic pandemic is HIV/AIDS, which originated from chimpanzees.
GettyImages

Aliza le Roux, University of the Free State and Bettine van Vuuren, University of Johannesburg

Zoology has an illustrious history; it has triggered paradigm shifts in thinking. One of the best known was Darwin’s theory of evolution, based on his observations of the natural world. It became the cornerstone of current zoological research.

Very few sub-disciplines of zoology are not firmly anchored on ideas around change over time, driven by some advantage that individuals get from specific heritable characteristics. In this spirit of observation of nature, linked to robust and detailed analyses of trends, zoologists have been sounding the alarm for many years about the current mass extinction and the negative consequences of disrespecting nature.

Those chickens have come home to roost.

Ultimately, COVID-19 is zoological in origin. And now, in the midst of the pandemic, it is modellers, virologists, medical specialists and engineers who are driving the scientific response to the global crisis.

Their role is crucial because they can contribute to preventing zoonotic outbreaks in future. But how? What could zoologists do differently?

Firstly, multidisciplinary research will be the cornerstone, forging links that haven’t existed before. Secondly, we will need to broaden our species focus. So far, research has targeted species known for carrying diseases that can infect other species – such as bats and primates. But this will need to be expanded to, for example, small carnivores.

What do we know already?

Zoologists have known for decades that some of the most virulent viral infections are animal in origin. These viruses occur naturally and at low levels. In their natural animal hosts they are often not harmful.

Viruses are not autonomous. They require the host’s DNA to replicate. Many viruses are therefore species-specific and cannot replicate outside their natural host. But a random mutation in the right location in the virus’s DNA can allow the virus to establish in a new host species.

Perhaps the best-known example is HIV/AIDS, which is simian (chimpanzee) in origin. Here, the simian immunodeficiency virus successfully transitioned to humans – through contact with animal blood or meat – to become the human immunodeficiency virus or HIV, causing AIDS.

Since the first record of HIV-1 in humans, this virus has mutated several times. The two main types present in humans have different animal origins. HIV-1 is closely related to viruses found in chimpanzees and gorillas (great apes), while HIV-2 is more closely related to viruses in sooty mangabeys (Old World monkeys) in West Africa.

We’re therefore dealing with at least two independent host jump events, and possibly many more. Decades after HIV-1 was identified and sequenced from humans, we are still no closer to a vaccine, and an estimated 32 million people (at the end of 2018) have died from AIDS-related illnesses since the start of the pandemic.

Very little is known about the coronavirus – SARS-CoV-2 – that causes COVID-19, even though it isn’t the first time that a member of the coronavirus family has jumped from its natural animal host to humans. According to the National Foundation for Infection Diseases fact sheet, human coronaviruses were first identified in the 1960s. Seven coronaviruses that can infect humans have since been identified.

These have included MERS-CoV, causing Middle East respiratory syndrome, or MERS, and SARS-CoV, causing severe acute respiratory syndrome, or SARS. The current pandemic is the result of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Initial ideas about SARS-CoV-2 were that it originated from two hosts – bats and later from pangolins. To date, the full genomes of more than 17,000 SARS-CoV-2 viruses have been sequenced, but the exact origin is still unknown.

This is important because to fully understand the properties of the virus, we need to know the animal host (so called patient zero). This information may be critical to developing vaccines.

It won’t be easy. There is a very real possibility that the origin of SARS-CoV-2 may be a bat. But they are difficult to work on, given their habits of nocturnality, flight, and roosting in places that are hard to access. And there’s a strong possibility that bat diversity is underestimated. This is a real problem given that viruses may be species-specific.

Focus areas

There are some simple steps that zoologists are following.

The first is to home in on data that we can collect easily but which will still provide relevant information.

One example is faeces. Defecation is near universal in the animal kingdom, and zoologists have been cashing in on the rich data that faeces can deliver. We collect, store and analyse faeces for parasite load, hormonal data and DNA, relating these data to the health, behaviour and social structures of species.

But this source of information can be mined for much more by, for example, taking advantage of advances in metagenomic sequencing. This means we can now use faeces – properly stored and prepared – to identify entire viromes in the wildlife hosts, enabling us to proactively identify potential zoonotic viruses.

This requires zoologists to make connections through linkages with virology and medical laboratories to provide multidisciplinary perspectives.

Another rich area that we can use more extensively is the massive volume of animal movement data. It has spawned a proliferation of websites dedicated to the sharing of GPS points tracking everything from ants to elephants, often using animal collars that transmit location signals. We understand that animal movement patterns can affect disease outbreaks and spillovers to humans; can’t we use these resources more proactively?

It’s vital for zoologists to collaborate with social scientists too, to understand human interaction with wildlife better. Ultimately, the jumps from animal to human are driven by us, and our behaviour. We can – and should – use the existing connections that many zoologists have with local communities to do more than reduce human-wildlife conflict.

This information provides rich pickings for zoologists as we battle to unravel the latest mysteries of what happens within species and between species.The Conversation

Aliza le Roux, Associate Professor, University of the Free State and Bettine van Vuuren, Professor, University of Johannesburg

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Hundreds of elephants are mysteriously dying in Botswana – a conservationist explains what we know


Vicky Boult, University of Reading

Worrying news has recently come to light: hundreds of elephants have been found dead in Botswana, and as yet, there is no clear cause of death. But as an expert in elephants and their conservation, I believe we can at least rule out a few possible answers.

Here’s what we do know: the first deaths were reported in March, but significant numbers were only recorded from May onwards. To date, it’s thought that the death toll stands at nearly 400 elephants of both sexes and all ages. Most of the deaths have occurred near the village of Seronga on the northern fringes of the Okavango Delta, a vast swampy inland region that hosts huge wildlife populations. Many of the carcasses have been found near to water.

Of those discovered so far, some lay on their knees and faces (rather than on their side), suggesting sudden death, although there are also reports of elephants looking disoriented and even walking in circles. The tusks of the dead elephants are still in place and, as yet, no other species have died under similar circumstances.

Botswana’s elephant politics

Botswana has long been a stronghold for Africa’s remaining 400,000 elephants, boasting a third of the continent’s population. While elephant numbers have widely declined in recent decades, largely due to poaching, Botswana’s population has grown.

However, this growth has been outpaced by the ever-increasing human population. With more elephants and more people, competition for space has escalated and increasingly, elephants and people find themselves at odds. Some communities see elephants as pests, as they feed on and trample crops, cause damage to infrastructure and threaten the lives of people and livestock. In return, people retaliate by killing and injuring offending elephants.

With large rural communities struggling to coexist with elephants, the issue has become highly politicised. In 2019, in a controversial move, president Mokgweetsi Masisi lifted a ban on the hunting of elephants in Botswana, reasoning that hunting could both reduce their numbers and generate income for struggling rural communities. This, against a backdrop of rising poaching, suggests that times are changing for Botswana’s elephants.

The elephants lived on the fringes of the Okavango Delta, a unique ‘desert wetland’.
evenfh / shutterstock

Speculation

This has sparked speculation about the recent deaths. However, given what we know, we can address some of the rumours.

Firstly, it seems unlikely that poachers are to blame, since the tusks of the dead elephants have not been removed. It’s estimated that illegal black-market ivory trade is responsible for the deaths of 20,000 elephants annually.

The elephants could have been killed by frustrated local people, typically by shooting or spearing. In this case however, the sheer number of dead elephants and the lack of reports of gunshot or spearing wounds, does not support this hypothesis.

Poisoning could be used instead, either by poachers or in retaliation by locals. A few years ago hundreds of elephants in Zimbabwe died after drinking from watering holes laced with cyanide, and the proximity of many of the recent deaths to water has given the idea some foundation.

However, in the event of poisoning, we would expect to see other species dying as well, either because they drank from the same poisoned water source or because they fed on the poisoned carcass of the elephant, and this has not been reported.

A natural cause of death?

If the evidence currently available doesn’t support foul play, that leads us to consider natural causes.

Drought can cause significant deaths. In 2009, a drought killed around 400 elephants in Amboseli, Kenya, a quarter of the local population. But drought tends to kill the very young and old, while the deaths recently reported in Botswana show elephants of all ages are affected. Moreover, rainfall in recent months has been near normal, ruling out the influence of drought.

Mount Kilimanjaro looms over Amboseli National Park.
Graeme Shannon / shutterstock

Perhaps because wildlife disease has gained much attention in light of the COVID-19 pandemic, the remaining possibility that has been widely suggested is disease. While COVID-19 itself is unlikely, elephants, like humans, are affected by a range of diseases.

For instance, over 100 were suspected to have died from an anthrax outbreak in Botswana in 2019. Those elephants that seemed disoriented and to be walking in circles might suggest a disease causing a neurological condition.

Still, the information currently available is inconclusive. The Botswana government has released a statement explaining that investigations are ongoing and that laboratories had been identified to process samples taken from the carcasses of dead elephants.

To avoid further speculation and prevent the deaths of more elephants in their last remaining stronghold, it’s vital that investigations are expedited so that the cause of death can be determined and suitable action taken.The Conversation

Vicky Boult, Postdoctoral Researcher in Conservation Biology, University of Reading

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Endangered tigers face growing threats from an Asian road-building boom



Female tiger crossing track, Bandavgarh National Park, India.
David Tipling/Universal Images Group/Getty Images

Neil Carter, University of Michigan

Tigers are one of the world’s most iconic wild species, but today they are endangered throughout Asia. They once roamed across much of this region, but widespread habitat loss, prey depletion and poaching have reduced their numbers to only about 4,000 individuals. They live in small pockets of habitat across South and Southeast Asia, as well as the Russian Far East – an area spanning 13 countries and 450,000 square miles (1,160,000 square kilometers).

Today Asia is experiencing a road-building boom. To maintain economic growth, development experts estimate that the region will need to invest about US$8.4 trillion in transportation infrastructure between 2016 and 2030.

Major investment projects, such as China’s Belt and Road Initiative – one of the largest infrastructure projects of all time – are fueling this growth. While roads can reduce poverty, especially in rural areas, many of Asia’s new roads also are likely to traverse regions that are home to diverse plants and animals.

To protect tigers from this surge of road building, conservation scientists like me need to know where the greatest risks are. That information, in turn, can improve road planning in the future.

In a newly published study, I worked with researchers at the University of Michigan, Boise State University and the University of British Columbia to examine how existing and planned Asian roads encroach on tiger habitats. We forecast that nearly 15,000 miles (24,000 kilometers) of new roads will be built in tiger habitats by 2050, and call for bold new planning strategies that prioritize biodiversity conservation and sustainable road development across large landscapes.

Economic growth in Asia means more roads will be built into tiger habitat. Planning at the outset can make these projects more tiger-friendly.

Letting humans in

Road construction worsens existing threats to tigers, such as poaching and development, by paving the way for human intrusion into the heart of the tiger’s range. For example, in the Russian Far East, roads have led to higher tiger mortality due to increased collisions with vehicles and more encounters with poachers.

To assess this threat across Asia, we focused on areas called Tiger Conservation Landscapes – 76 zones, scattered across the tiger’s range, which conservationists see as crucial for the species’ recovery. For each zone we calculated road density, distance to the nearest road and relative mean species abundance, which estimates the numbers of mammals in areas near roads compared to areas far from roads. Mean species abundance is our best proxy for estimating how roads affect numbers of mammals, like tigers and their prey, across broad scales.

We also used future projections of road building in each country to forecast the length of new roads that might be built in tiger habitats by 2050.

Overpasses and underpasses, like this one in Florida, help wild animals traverse highways safely.

More roads, fewer animals

We estimated that more than 83,300 miles (134,000 kilometers) of roads already exist within tiger habitats. This is likely an underestimate, since many logging or local roads are missing from the global data set that we used.

Road densities in tiger habitat are one-third greater outside of protected areas, such as national parks and tiger reserves, than inside of protected areas. Non-protected areas averaged 1,300 feet of road per square mile (154 meters per square kilometer), while protected areas averaged 980 feet per square mile (115 meters per square kilometer). For tiger populations to grow, they will need to use the forests outside protected areas. However, the high density of roads in those forests will jeopardize tiger recovery.

Protected areas and priority conservation sites – areas with large populations of tigers – are not immune either. For example, in India – home to over 70% of the world’s tigers – we estimate that a protected area of 500 square miles, or 1,300 square kilometers, contains about 200 miles (320 kilometers) of road.

Road networks are expansive. Over 40% of areas where tiger breeding has recently been detected – crucial to tiger population growth – is within just 3 miles (5 kilometers) of a nearby road. This is problematic because mammals often are less abundant this close to roads.

In fact, we estimate that current road networks within tiger habitats may be reducing local populations of tigers and their prey by about 20%. That’s a major decrease for a species on the brink of extinction. And the threats from roads are likely to become more severe.

Estimated road densities for 76 tiger conservation landscapes (colored zones), with darker red indicating more roads per unit area.
Neil Carter, CC BY-ND

Making infrastructure tiger-friendly

Our findings underscore the need for planning development in ways that interfere as minimally as possible with tiger habitat. Multilateral development banks and massive ventures like the Belt and Road Initiative can be important partners in this endeavor. For example, they could help establish an international network of protected areas and habitat corridors to safeguard tigers and many other wild species from road impacts.

National laws can also do more to promote tiger-friendly infrastructure planning. This includes keeping road development away from priority tiger populations and other “no go” zones, such as tiger reserves or habitat corridors.

Zoning can be used around infrastructure to prevent settlement growth and forest loss. Environmental impact assessments for road projects can do a better job of assessing how new roads might exacerbate hunting and poaching pressure on tigers and their prey.

Funding agencies need to screen proposed road developments using these tiger-friendly criteria before planners finalize decisions on road design, siting and construction. Otherwise, it might be too late to influence road planning.

There are also opportunities to reduce the negative effects of existing roads on tigers. They include closing roads to vehicular traffic at night, decommissioning existing roads in areas with important tiger populations, adding road signs announcing the presence of tigers and constructing wildlife crossings to allow tigers and other wildlife to move freely through the landscape.

Roads will become more pervasive features in Asian ecosystems as these nations develop. In my view, now is the time to tackle this mounting challenge to Asian biodiversity, including tigers, through research, national and international collaborations and strong political leadership.

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Neil Carter, Assistant Professor of Wildlife Conservation, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.