Diseases that can pass between animals and humans are called ‘zoonotic’. In most cases, illness tends to pass from the animal to the person, but the reverse can also happen. Pets can be sources of disease that can pass to owners. So it’s worth being aware of some of the more common ones. And think about sensible precautions to take to limit risk. There are actually over one hundred diseases that are classified as zoonotic, but most of them are very rare.
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Let’s start with a biggie. Rabies is a very serious disease and is almost always fatal to both animals and humans once symptoms develop. It is one of the more common zoonoses worldwide and can be transmitted to humans via a variety of animals, including cats. Rabies is caught via a bite from an infected animal. Infected cats will show symptoms which include altered behaviour and aggression, significant drooling and a hanging jaw, fever, staggering and in-coordination, and finally seizures and paralysis.
We are fortunate in the U.K. to be a rabies free country. Any cases in the U.K. are ‘notifiable’ – they are required by law to be reported to the relevant authority. However, cats that have been abroad can have been infected elsewhere. All cats entering the U.K. are required to have been vaccinated by law. Or else to quarantine for at least 4 months in case they are carrying the virus. If you are concerned your cat has rabies, keep them contained and seek veterinary advice. If you have been bitten by a cat with any of the above symptoms, or by a stray cat in a country that is not rabies-free, seek medical advice immediately. It is advisable not to touch stray cats, especially those abroad.
Given that Covid-19 is a relatively new disease, scientists are still investigating the risks of transmission from pets to their owners. It appears to be possible, but quite rare, for infected people to pass coronavirus to their cats. There is currently no known evidence of cats passing the disease to their owners directly.
However, it is well known that the Covid-19 virus can survive in the environment for a short time; on surfaces, packaging, and the like. This means that virus particles may be able to survive on the fur of your cat. Then infect a person who has contact with them. It is therefore recommended to maintain good hygiene around your cat, avoid cuddling them if you are infected with Covid, and to be vigilant about hand hygiene after touching them, especially if they are known to visit other people’s houses.
Toxoplasmosis is one of the most well-known zoonotic diseases that affects cats and humans. But there is a lot of misinformation spread about the role that cats play.
Infection in cats
Toxoplasmosis is caused by infection by a parasite: Toxoplasma gondii. The parasite is common, and extremely well-adapted, which means it can be found in many warm-blooded animals. But it is actually rare for it to cause significant harm. In cats, clinical symptoms are very uncommon, but it can cause various signs including fever and weight loss, inflammatory eye conditions such as uveitis, liver disease with accompanying jaundice, and neurological signs such as seizures. Infection in pregnant queens can lead to abortion or stillbirth. Infection is fairly common in cats, especially active hunters, but the majority will not show signs. Once infected, the parasite can lie dormant in cysts in muscle tissue, so many cats remain infected for life.
Infection in people
Infection in people is also fairly common, but as with cats, clinical symptoms are rare. People can catch T gondii through infected raw or undercooked meat, contaminated material, or cat faeces containing T gondii oocysts. Most people will experience no illness at all or very mild ‘fluey’ signs. However, some people are more vulnerable: this includes the elderly, babies and children, the immunosuppressed, and pregnant women. These higher-risk groups are more likely to develop severe diseases. Such as inflammation of the brain, abortion, stillbirth or birth defects, and problems with the eyes and nervous system.
It has actually been shown that owning a cat, or having contact with cats, does not increase the likelihood of infection with T gondii.
The biggest risk factor by far is the consumption of undercooked meat. However, it is still recommended to practise excellent hygiene around cat litter trays, and that at-risk groups such as pregnant women should avoid handling and changing cat litter trays.
Cat Scratch Disease
This is caused by bacteria called Bartonella henselae, a bacteria found in cats which can be transmitted to humans – but not commonly. It passes between cats via fleas, but needs a bite or scratch from an infected cat to reach a person. Cats and people have similar symptoms: fever, lethargy, appetite loss and swollen glands and may need antibiotics to be treated.
Despite the misleading name, ringworm is actually caused by fungi – usually Microsporum or Trichophyton. It causes skin disease in cats: mostly multiple round patches of scaly skin and hair loss, which are usually not itchy or irritating to the cat. Infection can be transmitted by direct contact, such as by stroking or cuddling your cat, and causes similar skin lesions in people. It is treated with shampoos or tablet medication from your vets. If your cat is affected, it is recommended to wear gloves when handling them and applying treatment, and wash hands thoroughly and often.
Like many other species – including humans, cats have lots of bacteria lurking around in their mouths, intestinal tracts and skin. One particular concern is that lots of cats carry a bacterium called Pasteurella spp. in their mouths, which can give a nasty infection to a person if bitten. Cat bites can be deep, and, as well as being washed as soon as possible, should be closely monitored for signs of infection such as redness, swelling, heat and pain. Cats can also excrete bacterial species such as Campylobacter and Salmonella in their faeces, which can cause diarrhoea and sickness in people. Good hygiene around litter trays is essential, especially if your cat has an upset tummy.
Worms and Fleas
Humans are not commonly the main host of most parasites we see in cats, but it is not uncommon for owners to be bitten by fleas if their cat is infested. Similarly, some species of parasitic worms can infect people, especially children and vulnerable adults. Preventative healthcare is really important for this reason, as well as keeping your cat healthy and happy.
Despite the list of diseases above, cats are not a hugely common source of disease for humans! Basic hygiene, especially around litter trays, is enough to prevent the majority of problems. Preventative healthcare such as parasite prevention treatments and vaccinations are also highly advisable. If you are ever concerned you may have contracted a zoonotic disease, please do seek medical attention.