Fellow street cat lovers beware: Research out today shows many felines we encounter outdoors are likely to be carrying all sorts of things that can sicken humans.
Veterinary researchers studied free-roaming cats in New York City. More than half were infected with parasites that could potentially be transmitted to humans, they found. Young male cats especially tended to be magnets for a certain group of roundworms.
The findings underscore “the public health risks associated with unmanaged feline populations in densely populated urban centers,” the researchers wrote in their paper, published Wednesday in PLOS-One.
Super-shedders
Cats are well known to be carriers of several zoonotic pathogens, meaning disease-causing bacteria, viruses, or parasites that can spread from animals to humans. According to the authors, however, there’s been little research examining how widely prevalent these parasites might be among free-roaming cats that call the Big Apple home. Free-roaming cats include strays, feral cats, and pet cats that regularly spend time outdoors.
The researchers examined blood and fecal samples collected from cats briefly captured through trap-and-neutering, or TNR, programs in NYC. These programs, in an effort to curb overpopulation, will humanely trap, neuter, and often vaccinate street cats against diseases like rabies before returning them back to the wild. All told, they studied 87 cats trapped between May and July 2023.
About 57% of cats tested positive for at least one internal zoonotic parasite that was being shed in their poop, the researchers found. Roughly 10% of cats also carried antibodies to Toxoplasma gondii, a parasite that can cause serious complications in pregnant women and other vulnerable populations.
The most common internal parasite carried by cats (54% of infected cats) was Toxocara, a type of roundworm that can cause fever and abdominal pain; the worms can also migrate to the eyes, causing vision problems. Young male cats in particular appeared to poop out a lot more Toxocara eggs than others, making them “super-shedders,” the researchers found.
“Because Toxocara eggs are highly robust, remaining infective in soil for years and withstanding the northeastern winter freeze-thaw cycles, environmental shedding by these cats presents a long-term public health risk,” they wrote.
What to do
While some of the parasites identified in the study only pose a low to moderate risk of being transmitted to people, others like T. gondii are widely prevalent among cats and humans alike (in the U.S., roughly 10% of people are thought to carry it).
The researchers say that keeping a close eye on free-roaming cats will allow scientists to track the emergence and spread of zoonotic parasites, hopefully before they become a larger problem. And they argue that TNR programs should try to preemptively eradicate them in these street cats, though that’s easier said than done.
The results from this study suggest that TNR programs should ideally be coupled with parasite control strategies where feasible, although the logistics of treating free-roaming populations remain challenging,” they wrote. “Collaboration between veterinarians, public health authorities, municipal park services, and wildlife managers can help map hotspots of contamination, implement targeted interventions, and monitor trends in zoonotic pathogen prevalence and environmental contamination over time.”
Unfortunately, this study will make me think twice about trying to ps-ps-ps the next wild-looking cat I see in my neighborhood, and it should probably do the same for you.
