A new study from the University of British Columbia suggests free-roaming cats could be to blame for the spread of the potentially deadly Toxoplasma gondii parasite in urban areas across the country.
The spread of the disease is affecting wildlife in densely populated areas, based on research led by UBC faculty of forestry adjunct Prof. Amy Wilson. During the study, researchers examined 45,079 cases of toxoplasmosis in wild mammals, using data from 202 global studies.
"As increasing human densities are associated with increased densities of domestic cats, our study suggests that free-roaming domestic cats — whether pets or feral cats — are the most likely cause of these infections," Wilson stated in a press release.
The results of the study found wildlife living near dense urban areas were more likely to be infected with toxoplasma. The disease has been linked to nervous system disorders, cancers and other debilitating chronic conditions
"This finding is significant because by simply limiting free-roaming of cats, we can reduce the impact of toxoplasma on wildlife."
Research indicated one infected cat can excrete as many as 500 million toxoplasma eggs in two weeks. The eggs can then live for years in soil and water with the potential to infect any bird or mammal, including humans. The study noted toxoplasmosis is particularly dangerous for pregnant people.
According to the European Advisory Board on Cat Diseases (EABCD) website, toxoplasma gondii infection is common in cats, with up to 50 per cent of felines, especially free-roaming ones, having antibodies indicating infection. Clinical signs usually appear when felines become immunosuppressed.
Cats become carriers by ingesting intermediate hosts, typically rodents, and the EABCD website said the key to preventing the spread is stopping pets from hunting and eating intermediate hosts.
If an animal is healthy, the parasite remains dormant and rarely causes direct harm. However, if an animal’s immune system has been compromised, the parasite can trigger illness and potentially death.
The UBC study also highlighted the way healthy forests, streams and other ecosystems can filter out dangerous pathogens like toxoplasma, Wilson said.
"We know that when wetlands are destroyed or streams are restricted, we are more likely to experience runoff that carries more pathogens into the waters where wild animals drink or live," she says. "When their habitats are healthy, wildlife thrives and tends to be more disease-resistant."
Brandon Humane Society shelter manager Tracy Munn said there are many diseases and illnesses cats can catch if they are allowed outside unsupervised. These sicknesses are largely driven by wild animals, like mice and birds, the cats interact with.
She noted there’s a city bylaw that forbids cats to wander free in Brandon and requires them to be licensed if they are six months of age or older.
"That bylaw is in place for a reason — number one, it’s dangerous your cat is going to bring home more disease, nothing carries more disease than mice and birds," Munn said. "Opening the door and letting them out is not OK. They carry disease, they destroy some people’s gardens … it’s just not right if you’re a responsible pet owner."
Toxoplasmosis is one of many diseases, including rabies, feline distemperment, feline infectious peritonitis and the feline leukemia virus, which can be spread when an animal is out in the wild.
Feline leukemia and feline infectious peritonitis are especially concerning, she added, because they are deadly for cats.
"It’s very contagious and animals do die," Munn said. "If you love your animal ... don’t let your animals out to roam. It’s dangerous — for your cat and your household."
Vaccines can help prevent the spread of illness and disease, but they do not guarantee the health of a pet if they are allowed outside on their own. Munn added it’s essential to get cats spayed or neutered to help limit population and disease growth.
When illnesses are allowed to run rampant in households and the community, the effects can be devastating.
Munn said there are a number of options available if a feline is looking for outside time. This can include training a cat to go for walks with a leash and harness or installing a "catio" that allows the animal to enjoy the great outdoors from the safety of a contained kennel.
She added the alternative option of letting a cat freely wander the city exposes them to multiple diseases affecting people and wildlife in the area.
"Do you want that in your household? Of course not, it makes people sick," Munn said. "Cats carry a lot of diseases. That’s why you don’t let them out."
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