Cats can share more than just their love around
You won’t find any ‘crazy cat lady’ jokes in this article because cat zoonosis is a serious matter. It is an infection that can be transmitted to humans from domesticated cats (Felis catus), sometimes in the most surprising ways.
“The most commonly known viral zoonosis is rabies,” advises Dr Sasha Jaksic, Medical Microbiologist at Dorevitch Pathology in Melbourne. While Australia and New Zealand are declared rabies free countries, it’s important for travellers to realise it’s not just a ‘dog’s disease’. “Both wild and domestic animals, including cats, can carry this infectious virus that is transmitted through animal bites and scratches, usually via saliva.”
There are also bacterial zoonoses. The bacterium Pasteurella multocida lives in the upper respiratory tracts of various livestock, poultry and domestic pet species, especially cats and dogs. It is most commonly passed on to humans from cats through a cat bite, although Dr Jaksic was involved in one unusual case.
“The patient had a recurrent sore throat and we couldn’t initially find the cause, but from one throat swab specimen we isolated P. multocida. When we asked the patient to monitor her cat’s activities, she discovered it was licking her toothbrush and passing P. multocida bacteria to her via infected saliva left on the toothbrush.”
Another bacterial zoonosis is cat scratch disease caused by Bartonella henselae. It is spread through bites and scratches from an infected cat that will almost always appear healthy.
Q Fever is caused by a bacterium called Coxiella burnetii. It is mainly spread from animals to humans via inhalation of infected particles in the air, but infection can occur from contact with infected animal products such as birth products (placenta), milk, urine and faeces. Usually thought of as a rural disease, urban cases do occur, such as the infamous outbreak of poker players’ pneumonia in Nova Scotia in 1987.
Dr Jaksic said a cat infected with C. burnetii was giving birth in the corner of a room where a dozen men were playing poker. The birth created a mist of infected particles that was breathed in by the card players. All became ill with Q Fever, and one player (who had underlying heart disease and a simultaneous bacterial blood infection) died.
Cats can also carry salmonella bacteria and excrete them in their faeces. “Salmonella infections are more common in cats that are fed raw food or that eat wild birds and animals. This is why it’s advisable to feed cats cooked or commercially processed food and to keep them inside,” says Dr Jaksic.
People can become infected after contact with an infected cat’s faeces such as when emptying a litter tray or inadvertently being exposed to it in the environment. “For example, cats love to go to the toilet in sandpits, and children can become infected when they play with sand where a cat has been to the toilet,” says Dr Jaksic.
A protozoan parasite can be a cat zoonosis too. Toxoplasmosis, for example, is caused by Toxoplasma gondii, and while cats aren’t the only way to become infected, they play an important role in spreading this parasite.
“The parasite is passed out in an infected cat’s faeces as oocysts, and these are not infectious for the first one to three days. This is why it’s important to clean a cat’s litter tray daily,” advises Dr Jaksic. If the cat is allowed outside it can contaminate the soil and water in the environment as well.
Dr Jaksic says toxoplasmosis can be very serious in people with compromised immune systems, and for babies born to an infected mother. “A pregnant woman can pass the infection to her unborn children, and while the mother may be asymptomatic, the baby can be born with congenital birth abnormalities,” she explained.
Another type of cat zoonosis is ringworm, although the name is misleading. “Ringworm is a fungal infection of the skin, hair and nails caused by cats infected with either Microsporum canis or Trichophyton species. A cat infected by these species of fungi will have lost fur, resulting in patches of bare, red skin,” says Dr Jaksic.
The spores from the fungus live on the cat’s fur, and are transferred to a person when they have contact with an infected cat’s fur by patting or cuddling it), or with an object or surface (think food bowl, bedding, carpet etc.) that has spores on it from the cat.
“Cats provide many benefits including companionship and helping to decrease stress and anxiety, but to enjoy only their benefits it’s important to manage the risks of infection,” explains Dr Jaksic.
“This means good hand washing after touching a cat or handling their faeces or litter trays, feeding them cooked or commercially prepared cat food, keeping your environment clean, regular veterinary care, and not being too intimate with your cat. That way, they will only share their love around, and not some of the nasties that can come with them.”
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This article appeared in the July 2017 Edition of ePathWay which is an online magazine produced by the Royal College of Pathologists of Australasia (http://www.rcpa.edu.au/Library/Publications/ePathway).
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