Is it okay to kiss your pet? The risk of animal-borne diseases is small but real

Our relationship with pets has changed drastically over the last few decades.

Pet ownership is at an all time high. A recent survey found that 69% of Australian households have at least one pet.

We spend an estimated A$33 billion caring for our fur babies each year.

While owning a pet comes with numerous mental and physical health benefits, our pets can also carry infectious diseases that can sometimes be transmitted to us. For most people, the risk is low.

However, some people, such as pregnant people and those with compromised immune systems, are at higher risk of contracting the disease from animals. Therefore, it is important to know the risks and take the necessary precautions to prevent infection.

What diseases can pets transmit?

Infectious diseases that are transmitted from animals to humans are called zoonoses or zoonoses. More than 70 pathogens are known to be transmissible from pets to humans.

Sometimes a pet that has a zoonotic pathogen looks sick. But often there are no visible symptoms, making it easier for you to catch the disease because you don’t suspect your pet is carrying germs.

Zoonoses can be transmitted directly from pets to humans, for example through contact with saliva, body fluids and faeces, or indirectly, for example through contact with contaminated litter, soil, food or water.

Studies indicate that the prevalence of pet-associated zoonoses is low. However, the actual number of infections is likely to be underestimated as many zoonoses are not ‘notifiable’ or may have multiple routes of exposure or generic symptoms.

Dogs and cats are major reservoirs of zoonotic infections (ie, the pathogens naturally live in their populations) caused by viruses, bacteria, fungi and parasites. In endemic areas of Africa and Asia, dogs are the main source of rabies, which is transmitted through saliva.

Dogs also commonly carry Capnocytophaga bacteria in their mouths and saliva, which can be transmitted to humans through close contact or bites.

The vast majority of people don’t get sick, but these bacteria can occasionally cause infections in people with compromised immune systems that can lead to serious illness and sometimes death. One such death was reported in Western Australia just last week.

Cat-associated zoonoses include a number of faecal-oral diseases such as giardiasis, campylobacteriosis, salmonellosis and toxoplasmosis. It is therefore particularly important to wash your hands or wear gloves when handling the litter box.

Cats can also sometimes transmit infections through bites and scratches, including the aptly named cat scratch disease, which is caused by the bacterium Bartonella henselae.

Both dogs and cats are also reservoirs for the methicillin-resistant bacterium Staphylococcus aureus (MRSA), with close contact with domestic animals considered an important risk factor for transmission of zoonoses.

Birds, turtles and fish can also transmit diseases

But not only dogs and cats can transmit diseases to humans. Pet birds can occasionally transmit psittacosis, a bacterial infection that causes pneumonia.

Contact with house turtles has been linked to salmonella infections in humans, particularly young children. Even pet fish have been linked to a number of human bacterial infections, including vibriosis, mycobacteriosis, and salmonellosis.

Close contact with animals – and some behaviors in particular – increase the risk of zoonotic transmission.

A study from the Netherlands found that half of owners allowed pets to lick their faces and 18% allowed dogs to share their bed. (Bed sharing increases the duration of exposure to pet-borne pathogens.) The same study found that 45% of cat owners allowed their cat to jump on the kitchen sink.

Pet kissing has also been linked to occasional zoonotic infections among pet owners. In one case, a woman in Japan developed meningitis due to Pasteurella multicoda infection after regularly kissing her dog’s face. These bacteria are common in the oral cavity of dogs and cats.

Young children are also more likely to engage in behaviors that increase their risk of contracting animal-borne diseases, such as putting their hands in their mouths after touching pets. Children are also less likely to wash their hands after handling pets.

Although anyone who comes into contact with a zoonotic agent through their pet can become ill, certain people are at higher risk of developing serious illness. These people include young, old, pregnant and immunocompromised people.

For example, while most people infected with the parasite toxoplasmosis experience only mild illness, they can be life-threatening or cause birth defects in fetuses.

What should I do if I’m afraid my pet might get a disease?

There are a number of good hygiene and husbandry practices that can reduce the risk of disease. These include:

• Wash your hands after playing with your pet, after handling bedding, toys, or cleaning up poop
• Don’t allow your pets to lick your face or open wounds
• Supervising young children playing with pets and washing hands after playing with pets
• Wear gloves when changing the litter box or cleaning the aquarium
• Wet bird cage surfaces when cleaning to minimize aerosols
• Keep pets away from the kitchen (especially cats, who may jump on food prep surfaces)
• Stay up to date on preventative veterinary care, including vaccinations and worm and tick treatments
• See a vet if you think your pet is unwell.

Taking precautions to reduce exposure to zoonotic agents is particularly important for people at increased risk of disease. And if you’re thinking about getting a pet, ask your veterinarian what kind of pet best suits your circumstances.

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Written by Sarah McLean, Enzo Palombo/The conversation.