Free-roaming cats in New York City harbor a surprising and concerning level of zoonotic infections, according to a recent study published in PLOS One. Researchers investigating the prevalence of endoparasites and Toxoplasma gondii seropositivity in feral Felis catus populations across the city’s boroughs have uncovered that over half of the sampled cats carry parasites with significant implications for human and animal health. The findings highlight the public health risks posed by urban feral cat populations, particularly younger male cats that act as prolific shedders of Toxocara roundworm eggs.
Zoonotic endoparasites are parasites capable of crossing species barriers and infecting humans, often causing serious disease. Toxocara spp., a genus of roundworms commonly found in cats, pose a well-documented threat when their eggs are shed into the environment, as they can cause visceral and ocular larva migrans in humans. Meanwhile, Toxoplasma gondii, a protozoan parasite transmitted through cat feces, is infamous for causing toxoplasmosis, which carries heightened risks for pregnant women and immunocompromised individuals.
The study utilized a combination of serological testing and fecal egg count analyses to determine infection statuses among free-roaming cats sampled from multiple New York City boroughs. Results showed that more than 50% harbored zoonotic parasites, with young male cats disproportionately contributing to environmental contamination given their status as “super-shedders.” This term refers to individuals that release parasite eggs or oocysts at rates significantly higher than the population average, amplifying transmission potential.
Technical assessment of the infection dynamics underscored important epidemiological points. The high prevalence of Toxocara eggs in feces from young males indicates that age and sex influence parasitic load and shedding intensity, potentially tied to hormonal, behavioral, and immune system factors. This biological insight is critical for designing effective control measures that target the key demographic responsible for parasite dissemination in urban ecosystems.
From a One Health perspective, the study raises awareness about the interface between free-roaming animal populations and urban residents. Toxoplasma gondii seropositivity among these cats confirms their role as definitive hosts facilitating the parasite’s lifecycle in cities. Ingesting or coming into contact with contaminated soil, water, or objects tainted with parasite eggs or oocysts can lead to human cases of zoonotic disease, necessitating proactive surveillance and public education efforts.
This research was funded by startup institutional grants from the Long Island University College of Veterinary Medicine and Rowan University’s Shreiber School of Veterinary Medicine. The authors noted no competing interests in the study, emphasizing its objective contribution to understanding zoonotic parasitic threats within metropolitan settings.
The implications of this work extend to urban wildlife management, veterinary public health policies, and community awareness programs. Strategies focusing on reducing feral cat populations, improving hygiene around public spaces, and informing at-risk groups about potential parasite exposure could mitigate the impacts detailed here. Further research into behavioral ecology and parasite-host interactions will be crucial to refining intervention approaches that balance ecological considerations with human health priorities.
As cities worldwide grapple with the challenges posed by free-roaming animal populations, studies like this one provide essential data spotlighting hidden urban health risks. Highlighting free-roaming young male cats as super-shedders of zoonotic parasites paves the way for targeted actions that protect both animal and human populations from the often-overlooked dangers lurking in dense urban environments.
Subject of Research: Zoonotic endoparasites and Toxoplasma gondii infections in free-roaming cats
Article Title: Zoonotic endoparasites and Toxoplasma gondii seropositivity in free-roaming cats (Felis catus) from New York City boroughs
News Publication Date: 8-Jul-2026
Web References: http://dx.doi.org/10.1371/journal.pone.0351437
Image Credits: Tatiana Mokhova, Unsplash, CC0
Keywords: zoonotic parasites, free-roaming cats, Toxocara, Toxoplasma gondii, urban health, super-shedders, New York City, endoparasites
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