In recent decades, there has been a significant transformation in our bond with pets. Pet ownership has reached unprecedented levels, with a recent survey revealing that 69% of Australian households now have at least one pet. As a nation, we dedicate an estimated A$33 billion annually to care for our beloved four-legged companions.
While the companionship of pets is associated with a multitude of mental and physical health benefits, it’s important to acknowledge that our pets can carry infectious diseases that can potentially be transmitted to us. For most individuals, the risk remains minimal, but there are segments of the population, such as pregnant individuals and those with weakened immune systems, who face greater susceptibility to illnesses contracted from animals. Therefore, it is essential to understand these risks and take appropriate precautions to prevent infections.
Understanding Pet-Borne Diseases
Infectious diseases that can transfer from animals to humans are termed zoonotic diseases or zoonoses. There are over 70 pathogens from companion animals known to be transmissible to people.
In some cases, pets carrying zoonotic pathogens may display visible signs of illness. However, oftentimes, there are no apparent symptoms, making it easier for these germs to be transmitted unknowingly because pet owners don’t suspect their furry companions of harboring harmful microorganisms.
Zoonoses can be transmitted directly from pets to humans through contact with saliva, bodily fluids, feces, or indirectly through contaminated bedding, soil, food, or water sources.
Research indicates that the prevalence of pet-associated zoonoses is relatively low. However, the actual number of infections is likely underreported, given that many zoonotic diseases are not “notifiable” and may manifest with generic symptoms or involve multiple exposure pathways.
Dogs and cats are significant reservoirs of zoonotic infections caused by viruses, bacteria, fungi, and parasites. In regions like Africa and Asia, dogs are the primary source of rabies, transmitted through saliva.
Dogs can also carry Capnocytophaga bacteria in their mouths and saliva, which, while harmless to most people, can occasionally lead to infections in individuals with weakened immune systems, potentially causing severe illnesses and, in rare cases, fatalities.
Cat-associated zoonoses encompass various illnesses, including giardiasis, campylobacteriosis, salmonellosis, and toxoplasmosis, typically spread through the fecal-oral route. This highlights the importance of handwashing and glove use when handling cat litter trays.
Additionally, cats may transmit infections through bites and scratches, such as cat scratch disease caused by Bartonella henselae bacteria.
Both dogs and cats can also be reservoirs for methicillin-resistant Staphylococcus aureus (MRSA), with close contact between pets and humans identified as a significant risk factor for zoonotic transmission.
Beyond Dogs and Cats: Other Potential Sources of Disease
Zoonotic diseases are not limited to dogs and cats. Pet birds can sporadically transmit psittacosis, a bacterial infection leading to pneumonia. Contact with pet turtles has been associated with Salmonella infections, particularly in young children. Even pet fish have been linked to various bacterial infections in humans, including vibriosis, mycobacteriosis, and salmonellosis.
Close contact with animals and specific behaviors can heighten the risk of zoonotic transmission. For instance, a Dutch study found that 50% of pet owners allowed their pets to lick their faces, while 18% permitted dogs to share their beds—a practice that prolongs exposure to pet-carried pathogens. The same study noted that 45% of cat owners allowed their feline friends to perch on the kitchen sink.
Kissing pets has also occasionally been linked to zoonotic infections in pet owners. In one instance, a woman in Japan contracted meningitis due to Pasteurella multicoda infection after regularly kissing her dog‘s face. These bacteria are commonly found in the oral cavities of dogs and cats.
Children, in particular, are more prone to behaviors that increase their risk of contracting animal-borne diseases, such as touching pets and then putting their hands in their mouths. They are also less likely to practice proper hand hygiene after handling animals.
While anyone coming into contact with zoonotic pathogens from their pets can potentially fall ill, certain groups are more susceptible to severe illnesses. These groups include the young, elderly, pregnant individuals, and those with compromised immune systems.
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