Can People Catch Diseases from Animals? Part 1

A dog showing signs of rabies

Around 12,000 years ago, humans domesticated their first animal, probably the dog, with goats, chickens, oxen, and horses following soon after. Ever since then, human and animal lives have been intertwined, and you probably won’t go a day without seeing an animal, even if you don’t own one yourself. If you are a pet owner, you’d probably agree that owning a pet makes life much more fun! But are there any negatives to owning a pet? Well one potential downside is the risk of catching a ‘zoonosis’, the topic we will be discussing in this short series of blogs.

 

What is a Zoonosis?

A zoonotic disease, or zoonosis, is any disease that can be transmitted from animals to humans. The numbers of zoonoses are huge, and range from simple illnesses to deadly pathogens. It is likely that the majority of human diseases once originated from animals – however, zoonosis usually refers to diseases that are, or can be, transmitted from animals to humans today.

The diseases themselves can be caused by bacteria, viruses, fungi, protozoa or parasites. The method of transmission varies too: they can be spread directly from animals by air, or in their saliva, blood, faeces, urine or other fluids; alternatively, they can be spread via intermediate vectors (such as biting insects) that come into contact with an animal and then a human, spreading the disease from them to us.

In general, the more contact we have with animals (or the vectors that spread the diseases), the more likely it is for us to catch a zoonosis – this means that zoos, farms, veterinary practices, animal sanctuaries, and areas with wild animals are all potential places to become infected. Our homes too have risks, from pets, pests, and even food. However do not fear – we live in a country where medical care and hygiene standards are very good, and the risk of catching zoonotic diseases is significantly lower than ever before. Nevertheless, it is important to know about some common zoonoses that can affect you, so precautions can be taken – these are what we will be discussing in the rest of the articles.

 

Rabies

We will start with one of the most well-known zoonotic diseases – rabies. Even if you aren’t entirely sure what rabies is, most people will know that getting bitten by a rabid dog means you can catch rabies. This is a good example of the direct spread of a zoonosis.

Rabies is a virus which replicates in the brain of humans and animals, causing the behavioural changes it is known for (aggression, restlessness, biting, frothing at the mouth, etc.). Rabies is actually spread by many animals, not just dogs, including bats, foxes, rodents, cats and farm animals. As mentioned above, rabies is primarily spread through saliva when you are bitten by an animal. It can rarely be spread if saliva gets onto an open wound or in your mouth. If a person is infected with rabies, they get a fever, behavioural changes, pain, fear of water, hallucinations, vomiting and ultimately death. To protect yourself, avoid contact with any aggressive, stray or unwelcome dogs, and wild animals. Should you be bitten, there thankfully is a vaccine for people that can prevent the serious symptoms. It can also be given before you visit a country where rabies is more common, so it might be worth checking with your doctor if you should have an injection before travelling.

We are lucky in this country that rabies is not currently present, but this is not the case in much of the world. UK law states that all pets entering or leaving the country must be vaccinated against rabies, as this is the best way to prevent spread of the disease. Quarantine and reporting of suspected rabid animals can further reduce this risk. Even if your dog is not a keen traveller, it is worth having them vaccinated anyway, just in case. Recently, more and more dogs are being brought in from countries that have poorer rabies control or ineffective vaccination policies, so it may unfortunately only be a matter of time until rabies makes an unwelcome visit to the UK. This is why it is important to be aware of rabies in both dogs and people, and ensure you are both vaccinated when necessary.

That’s the nightmare scenario – but in the second part of the series, we’ll look at some more common zoonotic conditions.

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