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Wildlife Diseases

All species great and small…

Wildlife Diseases

All species great and small

If your idea of a vet is someone who appears in TV programmes such as Animal Rescue or dramas such as All Creatures Great and Small, think again. Today, the modern vet could be doing post-mortems on eagles in Scotland, then tomorrow could be in West Africa to investigate the links between bats and Ebola, or coming up with bright ideas for wildlife conservation – which, come to think of it, would make a good plot for a new TV drama...

People send her dead red squirrels in the post. A ranger working for Scottish Natural Heritage phoned up one day to ask if she’d investigate the “mysterious deaths” of hundreds of newts on the island of Rum. And it’s all in a day’s work for Professor Anna Meredith, the former head vet at Edinburgh Zoo, and now Personal Chair of Zoological and Conservation Medicine at the Royal (Dick) School of Veterinary Studies, who has become a leading specialist in conservation medicine, concerned with the overall health of the Earth’s ecosystems – not just with treating sick exotic animals, wildlife or pets.

Although it may seem like a long way from her childhood dream of helping cats and dogs to “curing” the planet, Meredith now focuses on animals of all sorts because they are all part of complex ecosystems.

Whether it is elephants or parasites, all creatures great and small could come under her microscope during the course of the day, and what she learns from them could have a major impact on the health of the rest of the animal kingdom – and human beings.

For example, after doing post-mortems on hundreds of red squirrels over a period of 10 years, Meredith and her team at the Royal (Dick) School discovered that they’re carrying a strain of human leprosy. It’s not thought to be a significant danger to humans in the UK and is “just another problem” for the squirrels, but the discovery could lead to further insights into leprosy, as well as the future wellbeing of one of Scotland’s most beloved species.

After studying the fate of the only amphibians living on Rum, Meredith discovered that the cause of the demise of the palmate newts was a rare form of parasite, found nowhere else in the country. The “murder weapon” has been found, but the scientists still don't know how the weird parasites got there or what the impact on newt populations will be.

But who cares? Does it matter if hundreds of newts die a premature death on a remote Scottish island? How much do we value red squirrels? Questions such as these need to be answered.

There are no easy answers to these questions but, in Meredith’s opinion, what matters is “the interconnectedness of all life on the planet and the importance of biodiversity.” Take away one single link in the chain, and the consequences could be catastrophic. Lose a single species, and you may even lose the key to the cure for a fatal disease that may not have been spotted yet by doctors. Above all, it's important that everyone tries to conserve the rich diversity of life, because we can never have all of the answers or know what the future will bring. “Ultimately, the health of humans and our domestic animals, as well as wildlife, all depend on a healthy functioning ecosystem, but human activity is damaging that, sometimes beyond repair,” she says.

“Conserving species for their own sake is probably wise, because every species – no matter how small – fulfils a role in an ecosystem,” says Meredith.

For Meredith, doing post-mortems on red squirrels is more than just doing “research for its own sake”; it is a useful reminder that many conservation studies often lead to unexpected breakthroughs, since the health of any species reflects what is happening in its environment, whether it is influenced by natural phenomena or human behaviour.

From cats and dogs to ecosystems

As Meredith embarked on her career as a vet 25 years ago, she also didn't know where it was leading. She qualified from the University of Cambridge in Veterinary Medicine in 1991, after a first degree in Physiological Sciences from the University of Oxford. She spent a year in general practice, then joined the Royal (Dick) School as a Lecturer in exotic animal and wildlife medicine, and was Head Vet at Edinburgh Zoo from 1992 to 2009. Today, she focuses on wildlife and conservation medicine and is also Director of Postgraduate Taught programmes and Programme Director for the MVetSci in Conservation Medicine.

Although she “always wanted to be a vet,” today she is concerned with the whole ecosystem and the balance between health and disease in different species, not just exotic animals and pets but wildlife in general. During her time at the Zoo, it was a natural progression from looking after wildlife in captivity to wildlife conservation in the wild. “I have always focused on the bigger picture,” she explains, “and recognised that vets have a big role to play in conservation research and our understanding of biodiversity.

Wild things

In recent years, Meredith has been involved in studies of wildcats, raptors, newts and red squirrels, amongst many others, with a focus on animal health and the impact of environmental factors such as human intervention, as well as the links between wildlife and human diseases. “There are complex inter-relationships between different species,” she says, “and studying wildlife can also have benefits for human health. There is no division between human and animal health, because we are all dependent on the environment – we are all animals.”

One of Meredith’s major concerns is emerging infectious diseases, 70% of which originate in wild animals and can then spread to humans – e.g., bird flu, or Ebola, which is “harboured” in bats. The chain of events is not simple, however, because it is not always clear if diseases spread because of human action, such as habitat and species loss due to deforestation, or because of the animal trade. “All of these affect conservation and biodiversity,” says Meredith, “and can amplify the impact of diseases.” And it is work in the laboratory which sheds light on the factors involved.

Animal extinction is another big topic, and Meredith is also concerned with the future of wildcats, threatened not only by habitat loss but also by hybridisation and diseases introduced by their near relatives, domestic cats. Red squirrels also suffer from diseases carried by alien animal species introduced by man, such as squirrel pox (introduced to the UK when grey squirrels were brought here), and Meredith and her colleagues have been mapping its progress as it spreads through the country.

Does focusing on some species mean we neglect many others? “Red squirrels and wildcats are iconic species,” says Meredith, “and that helps draw attention to the much wider issues involved. The ecosystem has been compared to an engine, where every nut and bolt has a key role to play – remove them and the engine may grind to a halt. Similarly, if we lose biodiversity, we increase the risk of disease.”

Wildlife research can also lead to unexpected breakthroughs, such as the discovery of leprosy in the red squirrels. There are two types of bacteria which cause leprosy in human skin, and both of them have now been identified in the red squirrels. Although Meredith points out that leprosy in squirrels is extremely unlikely to spread to humans, she also notes that the disease still affects 250,000 people worldwide. And who knows what the study of red squirrels may reveal about cures for leprosy in the future?

“This is an exciting discovery,” says Meredith, “and without long-term wildlife surveillance we would never have found it.”

The reintroduction of beavers in Scotland is a classic example of conservation medicine in action, says Meredith, while her study of newts is a more offbeat project which could lead to equally interesting insights in future.

Meredith explains that the newt project started 10 years ago, when the SNH noticed the mass deaths of newts on the island of Rum. She initially went to Rum and brought some newts back to the lab, where she and her colleagues identified a new parasitic (fungal) disease not then found anywhere else in the world. As it happens, newts are the only amphibians living on Rum, so it is currently a mystery how they acquired this disease. The scientists also linked the disease with water quality, because it seems more severe in more alkaline ponds – the concern is that disease could lead to the extinction of the newts on the island, just as infectious diseases have recently wiped out many other amphibian species. Meredith acknowledges that agonising over newts may seem obscure, but also points out that we never know what the research may reveal.

According to Meredith, no-one has studied the health and wellbeing of Scottish raptors in depth before, largely because they are threatened more by human persecution and habitat loss. Recent research is beginning to show how the raptors are also affected by toxins, including heavy metals, pesticides and rodenticides which raptors ingest in their prey. Pesticides including DDT have been identified as significant problems in the past, also affecting reproduction in humans when they enter the food chain, so research into raptors may also uncover new threats to humans, as well as protecting the raptors.

“The raptors may be sentinels for human health,” says Meredith, “like many other species in the wild, revealing more insidious, less obvious factors.”

Conservation medicine

In the course of Meredith’s career, veterinary medicine has changed out of all recognition, and interest in ecology and the complex inter-relationships between different species has also exploded, with more and more governments growing concerned and committing to environmental programmes. Looking after sick exotic animals or pets will always be very important, and can also have a huge psychological impact on owners, but new careers in veterinary and conservation medicine are opening up, creating greater opportunities than ever before. “As a vet, I actually spend most of my time dealing with people,” says Meredith, “and vets today have a key role to play as part of interdisciplinary teams in ecosystem health as well as animal health, and there are benefits in every direction, including human health and economics – tourism and agriculture as well as the environment in general.”

Meredith believes that conservation underpins everything, and that understanding the importance of biodiversity should be embedded in government and education. “We must keep the momentum going,” she says. “We need
to have a good, robust science-based influence on policy, to tackle the big challenges we face in looking after the environment – and ultimately the health of the planet itself.”

It may be a big leap from squirrels and newts to the planet, but Meredith and other vets are gathering the scientific evidence to demonstrate the inter-dependence of life forms and, in the process, could be benefitting animal and human health. Maybe it’s not such a big step from Animal Rescue to trying to rescue the Earth?



Conservation medicine online

Professor Anna Meredith is the Director of Postgraduate Education at the Royal (Dick) School and has developed a new Masters Programme in Conservation Medicine, with over 50 students currently enrolled in countries all around the world, as part of “the world’s only online course in conservation medicine.” As a new generation of graduates enters the workforce, Meredith hopes they will go on to make a big difference in conservation, whether they are focusing on wildlife or pets. “It has become an interdisciplinary subject,” she continues, “with ecologists, zoologists and biologists working side by side with vets and social scientists, as well as with chemists and geologists.”




"Wildlife Diseases". Science Scotland (Issue Twenty-one)
Printed from on 06/07/20 12:13:12 AM

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