Emerging infectious diseases in animals are a key hot topic and something you’re likely to be asked about in a veterinary school interview – as well as something you’ll deal with regularly in your career as a vet. This topic can involve a lot of complicated terminology and knowledge, so read on for a comprehensive and clear overview to help you ace that interview!

What are Emerging Infectious Diseases?

If you were at all affected by the Covid-19 pandemic, you’ve experienced the threat of emerging infectious diseases in animals. Behind the scenes, vets are working hard to both monitor and manage new diseases that affect animals, often with an awareness that they may spread to humans.

Many of the pandemics you will have read about, or lived through, originated in animals and spread to humans: think like Covid-19, but also other pathogens like Ebola, avian influenza, or Mpox (previously known as monkeypox).

‘Emerging infectious diseases’ is a broad term, and, confusingly, it can mean several subtly different things. Essentially, an emerging infectious disease is either:

  • A completely new infectious disease that has never been seen before either in humans or animals and is now causing infections (Covid-19 is an example – it wasn’t known to science before the pandemic)
  • An infectious disease that was previously known about, but that is now spreading in a new area or in a new host, or a lot more quickly than before (the 2022 Mpox outbreak is an example – it was previously known about, but hadn’t spread outside of Africa) 

You might also hear the term ‘reemerging infectious disease’ to refer to a disease that we thought was no longer spreading or was declining but is now coming back, such as tuberculosis or cholera.

Emerging infectious diseases are highly relevant to vets as 60-80% of emerging infectious diseases come from animal sources. To put it very simply, this is because diseases ‘jump’ between species, so a disease that previously infected animals becomes able to infect humans.

This is thought to be the origin story of many serious human pandemics (not just Covid-19), including HIV/AIDS, SARS, and even the 1918 flu pandemic that killed around 50 million people.

There are lots of factors that potentially explain why diseases make this ‘jump’. It’s important to be aware that this is not just a biological process. Social and cultural changes, especially ones that bring people into contact with wild animals, also play a key role in emerging infectious disease in animals.

Showing a holistic understanding of the problem will be crucial in showing your interviewer that you have a thoughtful and reflective understanding of this issue. 

Some factors which contribute to the emergence and spread of these diseases that you may want to think about are:

  • Microbe evolution: as pathogens evolve, they may gain abilities to evade the human immune system or invade human cells. Antigenic shift in influenza viruses is a particularly relevant form of microbial evolution here as it is directly linked to animal viruses gaining the ability to affect humans: influenza’s ability to do this is part of why avian flu is such a serious public health concern.
  • Ecological changes: changes in the environment, like dam building, deforestation or urbanisation (think urban farming), bring humans into contact with new animals in new ways. Climate change can also bring humans and animals into contact, as warmer areas allow insects to expand their ranges, for example.
  • Social factors: poverty may lead people to hunt or consume bushmeat, or to rear livestock at home, for example. Social unrest, including civil war, may lead people to flee into new areas and become exposed to new animals and their pathogens. People who are starving or lack access to healthcare or hygienic washing are at greater risk of developing diseases when exposed to new microbes. At the same time, globalisation makes the world more connected than ever, allowing the pathogens to spread.
  • New technologies: technology like xenotransplantation may create new routes for infections to spread.

What Are Zoonotic Diseases?

A ‘zoonotic disease’, or ‘zoonosis’, is a disease that has successfully made that ‘jump’ from animals to humans. Most of the emerging infectious diseases discussed so far, like Covid-19, Ebola or Mpox, are zoonoses. As we’ve seen, they have significant public health implications and can cause severe disease outbreaks.

Vets are key players in controlling and preventing zoonotic diseases, in lots of different ways:

  • Monitoring animal populations for signs of illness
  • Making sure unwell animals are isolated from others and the disease does not spread
  • Working with governments and colleagues to spread awareness 
  • Helping the public to take action to prevent the spread of zoonoses, like checking dogs for ticks to prevent the ticks passing Lyme disease to humans
  • Laboratory research to identify and find treatments for zoonotic diseases

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Role of Veterinarians in Managing Emerging Diseases

Veterinarians are key players on the front line of managing emerging diseases. Emerging infectious diseases are increasingly understood using a One Health approach which recognises that human, animal and planetary health are fundamentally intertwined.

This means that vets are often working closely in collaboration with doctors, government officials, environmental scientists and others to manage and prevent emerging infectious diseases. Some vets work directly with the government to monitor and contain outbreaks.

As well as policy work, vets act to prevent emerging infectious disease every day at work. One example is rabies vaccinations: the strict vaccination requirements and schedule is designed to prevent rabies spreading and becoming a human health threat.

Educating the public about the role they can play in preventing emerging infectious disease is also crucial, such as by encouraging people to consider adopting animals at home rather than abroad, where bringing them back to the UK may allow diseases to spread. Try asking a vet on work experience about zoonoses and how they impact their daily working life: you might be surprised!

Investigating New Pathogens

Some vets will work in laboratories and be involved in directly identifying and discovering new diseases. Investigating new diseases begins with realising they are out there using complex and thorough systems of surveillance, looking at the news alongside medical data.

When a new disease is suspected, scientists will then try to identify it in a lab, using techniques like genomic sequencing to get a better idea of what the new pathogen is. This allows other scientists to build on this work to develop vaccines and treatments.

Like most healthcare professionals, veterinary medics are less likely to be part of the scientific challenge, and more likely to be on the ground treating patients and managing the disease on the front lines.

For vets, this might look like testing animals, diagnosing them with a new disease, and helping owners isolate their pets. For example, during Covid-19, vets worked to protect ferrets who can become infected with and spread Covid-19. 

Interview Preparation: Discussing Emerging Infectious Diseases in Interviews

There are several ways veterinary schools might ask about emerging infectious diseases in interviews: they might ask a broad, direct question like  “What do you see as the biggest challenge in controlling emerging infectious diseases in animals?”, ask about a recent zoonosis, or ask more broadly about what you have read recently. This can also be a great opportunity to show off everything you know about emerging infectious diseases in animals! 

In your interviews, be sure to be specific when necessary. All emerging infectious diseases in animals is a huge topic, so make sure to use one or two good examples rather than keeping your answer too broad.

You may also want to make sure to explain clearly why veterinary medics need to be interested in human and ecological health: many zoonoses are less of a concern for animals (although some very much are, like bovine tuberculosis or avian flu) than they are for humans!


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